Volunteer Suicide on Debian Day and other avoidable deaths

Debian, Volunteer, Suicide


November 29, 2023

hackergotchi for Jonathan Dowland

Jonathan Dowland

Useful vim plugins: AnsiEsc

Sometimes I have to pore over long debugging logs which have originally been written out to a terminal and marked up with colour or formatting via ANSI escape codes. The formatting definitely makes reading them easier, but I want to read them in Vim, rather than a terminal, and (out of the box) Vim doesn't render the formatting.

Cue AnsiEsc.vim: an OG Vim script1 that translates some ANSI escape codes — in particular some colour specifying ones — into Vim syntax highlighting.

This makes viewing and navigating around multi-MiB console log files much nicer.

  1. AnsiEsc is old enough to have been distributed as a script, and then as a "vimball", an invention of the same author to make installing Vim scripts easier. It pre-dates the current fashion for plugins, but someone else has updated it and repackaged it as a plugin. I haven't tried that out.

29 November, 2023 10:50AM

November 28, 2023

hackergotchi for Dirk Eddelbuettel

Dirk Eddelbuettel

RcppSimdJson 0.1.11 on CRAN: Maintenance

A new maintenance release 0.1.11 of the RcppSimdJson package is now on CRAN.

RcppSimdJson wraps the fantastic and genuinely impressive simdjson library by Daniel Lemire and collaborators. Via very clever algorithmic engineering to obtain largely branch-free code, coupled with modern C++ and newer compiler instructions, it results in parsing gigabytes of JSON parsed per second which is quite mindboggling. The best-case performance is ‘faster than CPU speed’ as use of parallel SIMD instructions and careful branch avoidance can lead to less than one cpu cycle per byte parsed; see the video of the talk by Daniel Lemire at QCon.

This release responds to a CRAN request to address issues now identified by -Wformat -Wformat-security. These are frequently pretty simple changes as it was here: all it took was an call to compileAttributes() from an updated Rcpp version which now injects "%s" as a format string when calling Rf_error().

The (very short) NEWS entry for this release follows.

Changes in version 0.1.11 (2023-11-28)

  • RcppExports.cpp has been regenerated under an update Rcpp to address a print format warning (Dirk in #88).

Courtesy of my CRANberries, there is also a diffstat report for this release. For questions, suggestions, or issues please use the issue tracker at the GitHub repo.

If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

28 November, 2023 10:57PM

hackergotchi for Steinar H. Gunderson

Steinar H. Gunderson

Framework debt

Today's shower thought:

Taking on a dependency is assuming some amount of technical debt. Using a framework is taking on a dependency that is very hard to get rid of.

(All the usual properties of technical debt, positive and negative, apply)

28 November, 2023 07:34PM

Enrico Zini

Introducing Debusine


Debusine manages scheduling and distribution of Debian-related tasks (package build, lintian analysis, autopkgtest runs, etc.) to distributed worker machines. It is being developed by Freexian with the intention of giving people access to a range of pre-configured tools and workflows running on remote hardware.

Freexian obtained STF funding for a substantial set of Debusine milestones, so development is happening on a clear schedule. We can present where we are and, we're going to be, and what we hope to bring to Debian with this work.

28 November, 2023 10:12AM

hackergotchi for Dirk Eddelbuettel

Dirk Eddelbuettel

RcppCNPy 0.2.12 on CRAN: More Maintenance

A new (and again somewhat minor) maintenance release of the RcppCNPy package arrived on CRAN earlier today.

RcppCNPy provides R with read and write access to NumPy files thanks to the cnpy library by Carl Rogers along with Rcpp for the glue to R.

Recent changes in r-devel hone in on issues concerning printf format string inaccuracies the compiler can detect via the -Wformat -Wformat-security flags. Two fairly simplye ones were present here and have been addressed. In the time since the last release about twenty months ago two or three other minor packaging and setup details have also been taken care of, details are below.

Changes in version 0.2.12 (2022-11-27)

  • The continuous integration workflow received a trivial update, twice.

  • The C++ compilation standard is now implicit per CRAN and R preference.

  • The CITATION file format has been updated for the current usage.

  • Two print format string issues reported by current R-devel have been addressed.

CRANberries also provides a diffstat report for the latest release. As always, feedback is welcome and the best place to start a discussion may be the GitHub issue tickets page.

If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

28 November, 2023 12:36AM

November 27, 2023

François Marier

Automatically rebooting for kernel updates

I use reboot-notifier on most of my servers to let me know when I need to reboot them for kernel updates since I want to decide exactly when those machines go down. On the other hand, my home backup server has very predictable usage patterns and so I decided to go one step further there and automate these necessary reboots.

To do that, I first installed reboot-notifier which puts the following script in /etc/kernel/postinst.d/reboot-notifier to detect when a new kernel was installed:


if [ "$0" = "/etc/kernel/postinst.d/reboot-notifier" ]; then

echo "*** System restart required ***" > /var/run/reboot-required
echo "$DPKG_MAINTSCRIPT_PACKAGE" >> /var/run/reboot-required.pkgs

Note that unattended-upgrades puts a similar script in /etc/kernel/postinst.d/unattended-upgrades:


      exit 0;;

if [ -d /var/run ]; then
    touch /var/run/reboot-required
    if ! grep -q "^$DPKG_MAINTSCRIPT_PACKAGE$" /var/run/reboot-required.pkgs 2> /dev/null ; then
        echo "$DPKG_MAINTSCRIPT_PACKAGE" >> /var/run/reboot-required.pkgs

and so you only need one of them to be installed since they both write to /var/run/reboot-required. It doesn't hurt to have both of them though.

Then I created the following cron job (/etc/cron.daily/reboot-local) to actually reboot the server:



if [ -s $REBOOT_REQUIRED ] ; then
    cat "$REBOOT_REQUIRED" | /usr/bin/mail -s "Rebooting $HOSTNAME" root
    /bin/systemctl reboot

With that in place, my server will send me an email and then automatically reboot itself.

This is a work in progress because I'd like to add some checks later on to make sure that no backup is in progress during that time (maybe by looking for active ssh connections?), but it works well enough for now. Feel free to leave a comment if you've got a smarter script you'd like to share.

27 November, 2023 11:32PM

Andrew Cater

20231123 - UEFI install on a Raspberry Pi 4 - step by step instructions to a modified d-i


 Andy (RattusRattus) and I have been formalising instructions for using Pete Batard's version of Tianocore (and therefore UEFI booting) for the Raspberry Pi 4 together with a Debian arm64 netinst to make a modified Debian installer on a USB stick which "just works" for a Raspberry Pi 4.

Thanks also to Steve McIntyre for initial notes that got this working for us and also to Emmanuele Rocca for putting up some useful instructions for copying.


Plug in a USB stick - use dmesg or your favourite method to see how it is identified.

Make a couple of mount points under /mnt - /mnt/data and /mnt/cdrom

1. Grab a USB stick, Partition using MBR. Make a single VFAT
   partition, type 0xEF (i.e. EFI System Partition)

For a USB stick (identified as sdX) below:

$ sudo parted --script /dev/sdX mklabel msdos 

$ sudo parted --script /dev/sdX mkpart primary fat32 0% 100% 

$ sudo mkfs.vfat /dev/sdX1 $ sudo mount /dev/sdX1 /mnt/data/

Download an arm64 netinst.iso


2. Copy the complete contents of partition *1* from a Debian arm64
   installer image into the filesystem (partition 1 is the installer
   stuff itself) on the USB stick, in /

$ sudo kpartx -v -a debian-12.2.0-arm64-netinst.iso 

# Mount the first partition on the ISO and copy its contents to the stick 

$ sudo mount /dev/mapper/loop0p1 /mnt/cdrom/ 

$ sudo rsync -av /mnt/cdrom/ /mnt/data/ 

$ sudo umount /mnt/cdrom

3. Copy the complete contents of partition *2* from that Debian arm64
  installer image into that filesystem (partition 2 is the ESP) on
   the USB stick, in /

# Same story with the second partition on the ISO

$ sudo mount /dev/mapper/loop0p2 /mnt/cdrom/

$ sudo rsync -av /mnt/cdrom/ /mnt/data/ $ sudo umount /mnt/cdrom

$ sudo kpartx -d debian-testing-amd64-netinst.iso $ sudo umount /mnt/data

4. Grab the rpi edk2 build from https://github.com/pftf/RPi4/releases
   (I used 1.35) and extract it. I copied the files there into *2*
   places for now on the USB stick:

   /      (so the Pi will boot using it)
   /rpi4  (so we can find the files again later)

5. Add the preseed.cfg file (attached) into *both* of the two initrd
   files on the USB stick

   - /install.a64/initrd.gz and
   - /install.a64/gtk/initrd.gz

   cpio is an awful tool to use :-(. In each case:

$ cp /path/to/initrd.gz .
$ gunzip initrd.gz
$ echo preseed.cfg | cpio -H newc -o -A -F initrd 

$ gzip -9v initrd

$ cp initrd.gz /path/to/initrd.gz

If you look at the preseed file, it will do a few things:

   - Use an early_command to unmount /media (to work around Debian bug

   - Register a late_command call for /cdrom/finish-rpi (the next
     file - see below) to run at the end of the installation.

   - Force grub installation also to the EFI removable media path,
     needed as the rpi doesn't store EFI boot variables.

   - Stop the installer asking for firmware from removable media (as
     the rpi4 will ask for broadcom bluetooth fw that we can't
     ship. Can be ignored safely.)

6. Copy the finish-rpi script (attached) into / on the USB stick. It
   will be run at the end of the installation, triggered via the
   preseed. It does a couple of things:

   - Copy the edk2 firmware files into the ESP on the system that's
     just been installer

   - Remove shim-signed from the installed systems, as there's a bug
     that causes it to fail on rpi4. I need to dig into this to see
     what the issue is.

That's it! Run the installer as normal, all should Just Work (TM).

BlueTooth didn't quite work : raspberrypi-firmware didn't install until adding a symlink for boot/efi to /boot/firmware

20231127 - This may not be necessary because raspberrypi-firmware path has been fixed


# The preseed file itself causes a problem - the installer medium is
# left mounted on /medis so things break in cdrom-detect. Let's see if
# we can fix that!
d-i preseed/early_command string umount /media || true

# Run our command to do rpi setup before reboot
d-i preseed/late_command string /cdrom/finish-rpi

# Force grub installation to the RM path
grub-efi-arm64  grub2/force_efi_extra_removable boolean true

# Don't prompt for missing firmware from removable media,
# e.g. broadcom bluetooth on the rpi.
d-i hw-detect/load_firmware boolean false



set -x

grep -q -a RPI4 /sys/firmware/acpi/tables/CSRT
if [ $? -ne 0 ]; then
    echo "Not running on a Pi 4, exit!"
    exit 0

# Copy the rpi4 firmware binaries onto the installed system.
# Assumes the installer media is mounted on /cdrom.
cp -vr /cdrom/rpi4/. /target/boot/efi/.

# shim-signed doesn't seem happy on rpi4, so remove it
mount --bind /sys /target/sys
mount --bind /proc /target/proc
mount --bind /dev /target/dev

in-target apt-get remove --purge --autoremove -y shim-signed

27 November, 2023 09:13PM by Andrew Cater (noreply@blogger.com)

November 26, 2023

hackergotchi for Dirk Eddelbuettel

Dirk Eddelbuettel

RQuantLib 0.4.20 on CRAN: More Maintenance

A new release 0.4.20 of RQuantLib arrived at CRAN earlier today, and has already been uploaded to Debian as well.

QuantLib is a rather comprehensice free/open-source library for quantitative finance. RQuantLib connects (some parts of) it to the R environment and language, and has been part of CRAN for more than twenty years (!!) as it was one of the first packages I uploaded there.

This release of RQuantLib brings a few more updates for nags triggered by recent changes in the upcoming R release (aka ‘r-devel’, usually due in April). The Rd parser now identifies curly braces that lack a preceding macro, usually a typo as it was here which affected three files. The printf (or alike) format checker found two more small issues. The run-time checker for examples was unhappy with the callable bond example so we only run it in interactive mode now. Lastly I had alread commented-out the setting for a C++14 compilation (required by the remaining Boost headers) as C++14 has been the default since R 4.2.0 (with suitable compilers, at least). Those who need it explicitly will have to uncomment the line in src/Makevars.in. Lastly, the expand printf format strings also found a need for a small change in Rcpp so the development version (now has that addressed; the change will be part of Rcpp 1.0.12 in January.

Changes in RQuantLib version 0.4.20 (2023-11-26)

  • Correct three help pages with stray curly braces

  • Correct two printf format strings

  • Comment-out explicit selection of C++14

  • Wrap one example inside 'if (interactive())' to not exceed total running time limit at CRAN checks

Courtesy of my CRANberries, there is also a diffstat report for the this release 0.4.20. As always, more detailed information is on the RQuantLib page. Questions, comments etc should go to the rquantlib-devel mailing list. Issue tickets can be filed at the GitHub repo.

If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

26 November, 2023 10:19PM

Andrew Cater

MiniDebConf Cambridge - 26th November 2023 - Afternoon sessions

That's all folks ...

Sadly, nothing too much to report.

I delivered a very quick three slides lightning talk on Accessibility, WCAG [Web Content Accessibility Guidelines] version 2.2 and a request for Debian to do better

WCAG 2.2:  WCAG 2.2 Abstract

Debian-accessibility mailing list link: debian-accessibility

I watched the other lightning talks but then left at 1500 - missing three good talks - to drive home at least partly in daylight.

A great four days - the chance to put some names to faces and to recharge in Debian spaces.

Thanks to all involved and especially ...

Thanks to Cambridge Debian folk for helping arrange evening meals, lifts and so on and especially to those who also happen be ARM employees who were badging us in and out through the four days

Thanks to those who staffed Front Desk on both days and, especially, also to the ARM security guards who let us into site at 0745 on all four days and to Mark who did the weekend shift inside the building for Saturday and Sunday.

Thanks to ARM for  excellent facilities, food, coffee, hosting us and coffee, to Codethink for sponsoring - and a lecture from Sudip and some interesting hardware - and Pexip for Pexip sponsorship (and employee attendance). 

Here's to the next opportunity, whenever that may be.

26 November, 2023 08:00PM by Andrew Cater (noreply@blogger.com)

Ian Jackson

Hacking my filter coffee machine

I hacked my coffee machine to let me turn it on from upstairs in bed :-). Read on for explanation, circuit diagrams, 3D models, firmware source code, and pictures.

Background: the Morphy Richards filter coffee machine

I have a Morphy Richards filter coffee machine. It makes very good coffee. But the display and firmware are quite annoying:

  • After it has finished making the coffee, it will keep the coffee warm using its hotplate, but only for 25 minutes. If you want to make a batch and drink it over the course of the morning that’s far too short.

  • It has a timer function. But it only has a 12 hour clock! You can’t retire upstairs on a Friday night, having programmed the coffee machine to make you coffee at a suitable post-lie-in time. If you try, you are greeted with apparently-inexplicably-cold coffee.

  • The buttons and UI are very confusing. For example, if it’s just sitting there keeping the coffee warm, and you pour the last, you want to turn it off. So you press the power button. Then the display lights up as if you’ve just turned it on! (The power LED is in the power button, which your finger is on.) If you know this you can get used to it, but it can confuse guests.

Also, I’m lazy and wanted to be able to cause coffee to exist from upstairs in bed, without having to make a special trip down just to turn the machine on.


My original feeling was “I can’t be bothered dealing with the coffee machine innards” so I thought I would make a mechanical contraption to physically press the coffee machine’s “on” button.

I could have my contraption press the button to turn the machine on (timed, or triggered remotely), and then periodically in pairs to reset the 25-minute keep-warm timer.

But a friend pointed me at a blog post by Andy Bradford, where Andy recounts modifying his coffee machine, adding an ESP8266 and connecting it to his MQTT-based Home Assistant setup.

I looked at the pictures and they looked very similar to my machine. I decided to take a look inside.

Inside the Morphy Richards filter coffee machine

My coffee machine seemed to be very similar to Andy’s. His disassembly report was very helpful. Inside I found the high-voltage parts with the heating elements, and the front panel with the display and buttons.

I spent a while poking about, masuring things, and so on.

Unexpected electrical hazard

At one point I wanted to use my storage oscilloscope to capture the duration and amplitude of the “beep” signal. I needed to connect the ’scope ground to the UI board’s ground plane, but then when I switched the coffee machine on at the wall socket, it tripped the house’s RCD.

It turns out that the “low voltage” UI board is coupled to the mains. In my setting, there’s an offset of about 8V between the UI board ground plane, and true earth. (In my house the neutral is about 2-3V away from true earth.)

This alarmed me rather. To me, this means that my modifications needed to still properly electrically isolate everything connected to the UI board from anything external to the coffee machine’s housing.

In Andy’s design, I think the internal UI board ground plane is directly brought out to an external USB-A connector. This means that if there were a neutral fault, the USB-A connector would be at live potential, possibly creating an electrocution or fire hazard. I made a comment in Andy Bradford’s blog, reporting this issue, but it doesn’t seem to have appeared. This is all quite alarming. I hope Andy is OK!

Design approach

I don’t have an MQTT setup at home, or an installation of Home Assistant. I didn’t feel like adding a lot of complicated software to my life, if I could avoid it. Nor did I feel like writing a web UI myself. I’ve done that before, but I’m lazy and in this case my requirements were quite modest.

Also, the need for electrical isolation would further complicate any attempt to do something sophisticated (that could, for example, sense the state of the coffee machine).

I already had a Tasmota-based cloud-free smart plug, which controls the fairy lights on our gazebo. We just operate that through its web UI. So, I decided I would add a small and stupid microcontroller. The microcontroller would be powered via a smart plug and an off-the-shelf USB power supply.

The microcontroller would have no inputs. It would simply simulate an “on” button press once at startup, and thereafter two presses every 24 minutes. After the 4th double press the microcontroller would stop, leaving the coffee machine to time out itself, after a total period of about 2h.

Implementation - hardware

I used a DigiSpark board with an ATTiny85. One of the GPIOs is connected to an optoisolator, whose output transistor is wired across the UI board’s “on” button.

circuit diagram; board layout diagram; (click for diagram scans as pdfs).

The DigiSpark has just a USB tongue, which is very wobbly in a normal USB socket. I designed a 3D printed case which also had an approximation of the rest of the USB A plug. The plug is out of spec; our printer won’t go fine enough - and anyway, the shield is supposed to be metal, not fragile plastic. But it fit in the USB PSU I was using, satisfactorily if a bit stiffly, and also into the connector for programming via my laptop.

Inside the coffee machine, there’s the boundary between the original, coupled to mains, UI board, and the isolated low voltage of the microcontroller. I used a reasonably substantial cable to bring out the low voltage connection, past all the other hazardous innards, to make sure it stays isolated.

I added a “drain power supply” resistor on another of the GPIOs. This is enabled, with a draw of about 30mA, when the microcontroller is soon going to “off”/“on” cycle the coffee machine. That reduces the risk that the user will turn off the smart plug, and turn off the machine, but that the microcontroller turns the coffee machine back on again using the remaining power from USB PSU. Empirically in my setup it reduces the time from “smart plug off” to “microcontroller stops” from about 2-3s to more like 1s.

Optoisolator board (inside coffee machine) pictures

(Click through for full size images.)

optoisolator board, front; optoisolator board, rear; optoisolator board, fitted.

Microcontroller board (in USB-plug-ish housing) pictures

microcontroller board, component side; microcontroller board, wiring side, part fitted; microcontroller in USB-plug-ish housing.

Implementation - software

I originally used the Arduino IDE, writing my program in C. I had a bad time with that and rewrote it in Rust.

The firmware is in a repository on Debian’s gitlab


I can now cause the coffee to start, from my phone. It can be programmed more than 12h in advance. And it stays warm until we’ve drunk it.

UI is worse

There’s one aspect of the original Morphy Richards machine that I haven’t improved: the user interface is still poor. Indeed, it’s now even worse:

To turn the machine on, you probably want to turn on the smart plug instead. Unhappily, the power button for that is invisible in its installed location.

In particular, in the usual case, if you want to turn it off, you should ideally turn off both the smart plug (which can be done with the button on it) and the coffee machine itself. If you forget to turn off the smart plug, the machine can end up being turned on, very briefly, a handful of times, over the next hour or two.


We had used the new features a handful of times when one morning the coffee machine just wouldn’t make coffee. The UI showed it turning on, but it wouldn’t get hot, so no coffee. I thought “oh no, I’ve broken it!”

But, on investigation, I found that the machine’s heating element was open circuit (ie, completely broken). I didn’t mess with that part. So, hooray! Not my fault. Probably, just being inverted a number of times and generally lightly jostled, had precipitated a latent fault. The machine was a number of years old.

Happily I found a replacement, identical, machine, online. I’ve transplanted my modification and now it all works well.

Bonus pictures

(Click through for full size images.)

probing the innards; machine base showing new cable route.

edited 2023-11-26 14:59 UTC in an attempt to fix TOC links

comment count unavailable comments

26 November, 2023 02:59PM

Andrew Cater

Back at ARM for MiniDebConf day 2 - Morning sessions 26th November 2023

 Quick recap of slides and safety information for the day from Steve McIntyre

Now into the Release Team questions following a release team overview.

A roomful of people all asking questions which are focused and provoke more questions - how unlike a Debian session :)

May just have talked myself into giving a lightning talk this afternoon :)

Now about to have a talk about from Sudip about OpenQA, kernel testing and automation

26 November, 2023 10:41AM by Andrew Cater (noreply@blogger.com)

November 25, 2023

Afternoon talks - MiniDebConf ARM Cambridge - Day 1

A great talk on SteamOS progress to effective boot loaders for atomic OS updates.

How to produce something that will allow instant updates and instant fallbacks when updating a whole OS image - lots of explanation - and it's good when three or four people who are directly interested in problems and solutions round, for example, Secure Boot are in the room.

Jessica Clarke on CHERI, Morello and security protections in hardware, software and programming hardware which has verifiable pointers and routines. A couple of flourishes which had the room breaking out in applause.

Roberto Sanchez and Santiago Rincon on suggestions for LTS and ways forward. The presentation very clearly set out what LTS is, is not, and maybe should be.

Last presentation of the day was from Ian Jackson on a potential change to git based working and tagging. 

Then lots of chasing around to get people out of the building. Thanks very much to the Arm personnel, especially the security staff who have been helpful throughout the day with getting us all in and out

Thanks to all involved with Arm, Codethink and Pexip for hosting and sponsorship without which this would not have been possible.


25 November, 2023 07:44PM by Andrew Cater (noreply@blogger.com)

Lightning talks - MiniDebConf ARM Cambridge - Day 1

 A quick one slide presentation from Helmut on how to use Debian without sudo - Sudo Apt Purge Sudo

A presentation on upcoming Ph.D research on Digital Obsolescence - from Eda

Antarctic and Arctic research from Carlos Pina i Estany 

* Amazing * what you can get into three well chosen slides.

Ten minutes until the afternoon's talks

25 November, 2023 01:52PM by Andrew Cater (noreply@blogger.com)

November 24, 2023

hackergotchi for Jonathan Dowland

Jonathan Dowland

Dockerfile ARG footgun

This week I stumbled across a footgun in the Dockerfile/Containerfile ARG instruction.

ARG is used to define a build-time variable, possibly with a default value embedded in the Dockerfile, which can be overridden at build-time (by passing --build-arg). The value of a variable FOO is interpolated into any following instructions that include the token $FOO.

This behaves a little similar to the existing instruction ENV, which, for RUN instructions at least, can also be interpolated, but can't (I don't think) be set at build time, and bleeds through to the resulting image metadata.

ENV has been around longer, and the documentation indicates that, when both are present, ENV takes precedence. This fits with my mental model of how things should work, but, what the documentation does not make clear is, the ENV doesn't need to have been defined in the same Dockerfile: environment variables inherited from the base image also override ARGs.

To me this is unexpected and far less sensible: in effect, if you are building a layered image and want to use ARG, you have to be fairly sure that your base image doesn't define an ENV of the same name, either now or in the future, unless you're happy for their value to take precedence.

In our case, we broke a downstream build process by defining a new environment variable USER in our image.

To defend against the unexpected, I'd recommend using somewhat unique ARG names: perhaps prefix something unusual and unlikely to be shadowed. Or don't use ARG at all, and push that kind of logic up the stack to a Dockerfile pre-processor like CeKit.

24 November, 2023 04:37PM


Last year I put together a Halloween playlist and tried, where possible, to link to the tracks on Bandcamp. At the time, Bandcamp did not offer a Playlist feature; they've since added one, but it's limited to mobile only (and I've found, not a lot of use there either).

(I also provided a Spotify playlist. Not all of the tracks in the playlist were available on Spotify, or Bandcamp.)

Since then I discovered an independent service bndcmpr which lets you build and share playlists from tracks hosted on Bandcamp.

I'm not sure whether it will have longevity, but for now at least, I've ported my Halloween 2022 playlist over to bndcmpr. You can find it here: https://bndcmpr.co/cae6814a, or with any luck, embedded below (if you are reading this post on an aggregation site, or newsreader, it's less likely that this will appear):

I'm overdue cutting the next playlist, theme TBA. Stay tuned.

24 November, 2023 04:27PM

November 23, 2023

hackergotchi for Bits from Debian

Bits from Debian

Discontinuing rsync service on archive.debian.org

The proposed and previously announced changes to the rsync service have become effective with archive.debian.org hostname now being discontinued.

The worldwide Debian mirrors network has served archive.debian.org via both HTTP and rsync. As part of improving the reliability of the service for users, the Debian mirrors team is separating the access methods to different host names:

  • http://archive.debian.org/ will remain the entry point for HTTP clients such as APT

  • rsync://rsync.archive.debian.org/debian-archive/ is now available for those who wish to mirror all or parts of the archives.

rsync service on archive.debian.org has stopped, and we encourage anyone using the service to migrate to the new host name as soon as possible.

If you are currently using rsync to the debian-archive from a debian.org server that forms part of the archive.debian.org rotation, we also encourage Administrators to move to the new service name. This will allow us to better manage which back-end servers offer rsync service in future.

Note that due to its nature the content of archive.debian.org does not change frequently - generally there will be several months, possibly more than a year, between updates - so checking for updates more than once a day is unnecessary.

For additional information please reach out to the Debian Mirrors Team maillist.

23 November, 2023 07:00AM by Donald Norwood, Adam D. Barratt

November 21, 2023

Mike Hommey

How I (kind of) killed Mercurial at Mozilla

Did you hear the news? Firefox development is moving from Mercurial to Git. While the decision is far from being mine, and I was barely involved in the small incremental changes that ultimately led to this decision, I feel I have to take at least some responsibility. And if you are one of those who would rather use Mercurial than Git, you may direct all your ire at me.

But let's take a step back and review the past 25 years leading to this decision. You'll forgive me for skipping some details and any possible inaccuracies. This is already a long post, while I could have been more thorough, even I think that would have been too much. This is also not an official Mozilla position, only my personal perception and recollection as someone who was involved at times, but mostly an observer from a distance.

From CVS to DVCS

From its release in 1998, the Mozilla source code was kept in a CVS repository. If you're too young to know what CVS is, let's just say it's an old school version control system, with its set of problems. Back then, it was mostly ubiquitous in the Open Source world, as far as I remember.

In the early 2000s, the Subversion version control system gained some traction, solving some of the problems that came with CVS. Incidentally, Subversion was created by Jim Blandy, who now works at Mozilla on completely unrelated matters. In the same period, the Linux kernel development moved from CVS to Bitkeeper, which was more suitable to the distributed nature of the Linux community. BitKeeper had its own problem, though: it was the opposite of Open Source, but for most pragmatic people, it wasn't a real concern because free access was provided. Until it became a problem: someone at OSDL developed an alternative client to BitKeeper, and licenses of BitKeeper were rescinded for OSDL members, including Linus Torvalds (they were even prohibited from purchasing one).

Following this fiasco, in April 2005, two weeks from each other, both Git and Mercurial were born. The former was created by Linus Torvalds himself, while the latter was developed by Olivia Mackall, who was a Linux kernel developer back then. And because they both came out of the same community for the same needs, and the same shared experience with BitKeeper, they both were similar distributed version control systems.

Interestingly enough, several other DVCSes existed:

  • SVK, a DVCS built on top of Subversion, allowing users to create local (offline) branches of remote Subversion repositories. It was also known for its powerful merging capabilities. I picked it at some point for my Debian work, mainly because I needed to interact with Subversion repositories.
  • Arch (tla), later known as GNU arch. From what I remember, it was awful to use. You think Git is complex or confusing? Arch was way worse. It was forked as "Bazaar", but the fork was abandoned in favor of "Bazaar-NG", now known as "Bazaar" or "bzr", a much more user-friendly DVCS. The first release of Bzr actually precedes Git's by two weeks. I guess it was too new to be considered by Linus Torvalds for the Linux kernel needs.
  • Monotone, which I don't know much about, but it was mentioned by Linus Torvalds two days before the initial Git commit of Git. As far as I know, it was too slow for the Linux kernel's needs. I'll note in passing that Monotone is the creation of Graydon Hoare, who also created Rust.
  • Darcs, with its patch-based model, rather than the common snapshot-based model, allowed more flexible management of changes. This approach came, however, at the expense of performance.

In this landscape, the major difference Git was making at the time was that it was blazing fast. Almost incredibly so, at least on Linux systems. That was less true on other platforms (especially Windows). It was a game-changer for handling large codebases in a smooth manner.

Anyways, two years later, in 2007, Mozilla decided to move its source code not to Bzr, not to Git, not to Subversion (which, yes, was a contender), but to Mercurial. The decision "process" was laid down in two rather colorful blog posts. My memory is a bit fuzzy, but I don't recall that it was a particularly controversial choice. All of those DVCSes were still young, and there was no definite "winner" yet (GitHub hadn't even been founded). It made the most sense for Mozilla back then, mainly because the Git experience on Windows still wasn't there, and that mattered a lot for Mozilla, with its diverse platform support. As a contributor, I didn't think much of it, although to be fair, at the time, I was mostly consuming the source tarballs.

Personal preferences

Digging through my archives, I've unearthed a forgotten chapter: I did end up setting up both a Mercurial and a Git mirror of the Firefox source repository on alioth.debian.org. Alioth.debian.org was a FusionForge-based collaboration system for Debian developers, similar to SourceForge. It was the ancestor of salsa.debian.org. I used those mirrors for the Debian packaging of Firefox (cough cough Iceweasel). The Git mirror was created with hg-fast-export, and the Mercurial mirror was only a necessary step in the process. By that time, I had converted my Subversion repositories to Git, and switched off SVK. Incidentally, I started contributing to Git around that time as well.

I apparently did this not too long after Mozilla switched to Mercurial. As a Linux user, I think I just wanted the speed that Mercurial was not providing. Not that Mercurial was that slow, but the difference between a couple seconds and a couple hundred milliseconds was a significant enough difference in user experience for me to prefer Git (and Firefox was not the only thing I was using version control for)

Other people had also similarly created their own mirror, or with other tools. But none of them were "compatible": their commit hashes were different. Hg-git, used by the latter, was putting extra information in commit messages that would make the conversion differ, and hg-fast-export would just not be consistent with itself! My mirror is long gone, and those have not been updated in more than a decade.

I did end up using Mercurial, when I got commit access to the Firefox source repository in April 2010. I still kept using Git for my Debian activities, but I now was also using Mercurial to push to the Mozilla servers. I joined Mozilla as a contractor a few months after that, and kept using Mercurial for a while, but as a, by then, long time Git user, it never really clicked for me. It turns out, the sentiment was shared by several at Mozilla.

Git incursion

In the early 2010s, GitHub was becoming ubiquitous, and the Git mindshare was getting large. Multiple projects at Mozilla were already entirely hosted on GitHub. As for the Firefox source code base, Mozilla back then was kind of a Wild West, and engineers being engineers, multiple people had been using Git, with their own inconvenient workflows involving a local Mercurial clone. The most popular set of scripts was moz-git-tools, to incorporate changes in a local Git repository into the local Mercurial copy, to then send to Mozilla servers. In terms of the number of people doing that, though, I don't think it was a lot of people, probably a few handfuls. On my end, I was still keeping up with Mercurial.

I think at that time several engineers had their own unofficial Git mirrors on GitHub, and later on Ehsan Akhgari provided another mirror, with a twist: it also contained the full CVS history, which the canonical Mercurial repository didn't have. This was particularly interesting for engineers who needed to do some code archeology and couldn't get past the 2007 cutoff of the Mercurial repository. I think that mirror ultimately became the official-looking, but really unofficial, mozilla-central repository on GitHub. On a side note, a Mercurial repository containing the CVS history was also later set up, but that didn't lead to something officially supported on the Mercurial side.

Some time around 2011~2012, I started to more seriously consider using Git for work myself, but wasn't satisfied with the workflows others had set up for themselves. I really didn't like the idea of wasting extra disk space keeping a Mercurial clone around while using a Git mirror. I wrote a Python script that would use Mercurial as a library to access a remote repository and produce a git-fast-import stream. That would allow the creation of a git repository without a local Mercurial clone. It worked quite well, but it was not able to incrementally update. Other, more complete tools existed already, some of which I mentioned above. But as time was passing and the size and depth of the Mercurial repository was growing, these tools were showing their limits and were too slow for my taste, especially for the initial clone.

Boot to Git

In the same time frame, Mozilla ventured in the Mobile OS sphere with Boot to Gecko, later known as Firefox OS. What does that have to do with version control? The needs of third party collaborators in the mobile space led to the creation of what is now the gecko-dev repository on GitHub. As I remember it, it was challenging to create, but once it was there, Git users could just clone it and have a working, up-to-date local copy of the Firefox source code and its history... which they could already have, but this was the first officially supported way of doing so. Coincidentally, Ehsan's unofficial mirror was having trouble (to the point of GitHub closing the repository) and was ultimately shut down in December 2013.

You'll often find comments on the interwebs about how GitHub has become unreliable since the Microsoft acquisition. I can't really comment on that, but if you think GitHub is unreliable now, rest assured that it was worse in its beginning. And its sustainability as a platform also wasn't a given, being a rather new player. So on top of having this official mirror on GitHub, Mozilla also ventured in setting up its own Git server for greater control and reliability.

But the canonical repository was still the Mercurial one, and while Git users now had a supported mirror to pull from, they still had to somehow interact with Mercurial repositories, most notably for the Try server.

Git slowly creeping in Firefox build tooling

Still in the same time frame, tooling around building Firefox was improving drastically. For obvious reasons, when version control integration was needed in the tooling, Mercurial support was always a no-brainer.

The first explicit acknowledgement of a Git repository for the Firefox source code, other than the addition of the .gitignore file, was bug 774109. It added a script to install the prerequisites to build Firefox on macOS (still called OSX back then), and that would print a message inviting people to obtain a copy of the source code with either Mercurial or Git. That was a precursor to current bootstrap.py, from September 2012.

Following that, as far as I can tell, the first real incursion of Git in the Firefox source tree tooling happened in bug 965120. A few days earlier, bug 952379 had added a mach clang-format command that would apply clang-format-diff to the output from hg diff. Obviously, running hg diff on a Git working tree didn't work, and bug 965120 was filed, and support for Git was added there. That was in January 2014.

A year later, when the initial implementation of mach artifact was added (which ultimately led to artifact builds), Git users were an immediate thought. But while they were considered, it was not to support them, but to avoid actively breaking their workflows. Git support for mach artifact was eventually added 14 months later, in March 2016.

From gecko-dev to git-cinnabar

Let's step back a little here, back to the end of 2014. My user experience with Mercurial had reached a level of dissatisfaction that was enough for me to decide to take that script from a couple years prior and make it work for incremental updates. That meant finding a way to store enough information locally to be able to reconstruct whatever the incremental updates would be relying on (guess why other tools hid a local Mercurial clone under hood). I got something working rather quickly, and after talking to a few people about this side project at the Mozilla Portland All Hands and seeing their excitement, I published a git-remote-hg initial prototype on the last day of the All Hands.

Within weeks, the prototype gained the ability to directly push to Mercurial repositories, and a couple months later, was renamed to git-cinnabar. At that point, as a Git user, instead of cloning the gecko-dev repository from GitHub and switching to a local Mercurial repository whenever you needed to push to a Mercurial repository (i.e. the aforementioned Try server, or, at the time, for reviews), you could just clone and push directly from/to Mercurial, all within Git. And it was fast too. You could get a full clone of mozilla-central in less than half an hour, when at the time, other similar tools would take more than 10 hours (needless to say, it's even worse now).

Another couple months later (we're now at the end of April 2015), git-cinnabar became able to start off a local clone of the gecko-dev repository, rather than clone from scratch, which could be time consuming. But because git-cinnabar and the tool that was updating gecko-dev weren't producing the same commits, this setup was cumbersome and not really recommended. For instance, if you pushed something to mozilla-central with git-cinnabar from a gecko-dev clone, it would come back with a different commit hash in gecko-dev, and you'd have to deal with the divergence.

Eventually, in April 2020, the scripts updating gecko-dev were switched to git-cinnabar, making the use of gecko-dev alongside git-cinnabar a more viable option. Ironically(?), the switch occurred to ease collaboration with KaiOS (you know, the mobile OS born from the ashes of Firefox OS). Well, okay, in all honesty, when the need of syncing in both directions between Git and Mercurial (we only had ever synced from Mercurial to Git) came up, I nudged Mozilla in the direction of git-cinnabar, which, in my (biased but still honest) opinion, was the more reliable option for two-way synchronization (we did have regular conversion problems with hg-git, nothing of the sort has happened since the switch).

One Firefox repository to rule them all

For reasons I don't know, Mozilla decided to use separate Mercurial repositories as "branches". With the switch to the rapid release process in 2011, that meant one repository for nightly (mozilla-central), one for aurora, one for beta, and one for release. And with the addition of Extended Support Releases in 2012, we now add a new ESR repository every year. Boot to Gecko also had its own branches, and so did Fennec (Firefox for Mobile, before Android). There are a lot of them.

And then there are also integration branches, where developer's work lands before being merged in mozilla-central (or backed out if it breaks things), always leaving mozilla-central in a (hopefully) good state. Only one of them remains in use today, though.

I can only suppose that the way Mercurial branches work was not deemed practical. It is worth noting, though, that Mercurial branches are used in some cases, to branch off a dot-release when the next major release process has already started, so it's not a matter of not knowing the feature exists or some such.

In 2016, Gregory Szorc set up a new repository that would contain them all (or at least most of them), which eventually became what is now the mozilla-unified repository. This would e.g. simplify switching between branches when necessary.

7 years later, for some reason, the other "branches" still exist, but most developers are expected to be using mozilla-unified. Mozilla's CI also switched to using mozilla-unified as base repository.

Honestly, I'm not sure why the separate repositories are still the main entry point for pushes, rather than going directly to mozilla-unified, but it probably comes down to switching being work, and not being a top priority. Also, it probably doesn't help that working with multiple heads in Mercurial, even (especially?) with bookmarks, can be a source of confusion. To give an example, if you aren't careful, and do a plain clone of the mozilla-unified repository, you may not end up on the latest mozilla-central changeset, but rather, e.g. one from beta, or some other branch, depending which one was last updated.

Hosting is simple, right?

Put your repository on a server, install hgweb or gitweb, and that's it? Maybe that works for... Mercurial itself, but that repository "only" has slightly over 50k changesets and less than 4k files. Mozilla-central has more than an order of magnitude more changesets (close to 700k) and two orders of magnitude more files (more than 700k if you count the deleted or moved files, 350k if you count the currently existing ones).

And remember, there are a lot of "duplicates" of this repository. And I didn't even mention user repositories and project branches.

Sure, it's a self-inflicted pain, and you'd think it could probably(?) be mitigated with shared repositories. But consider the simple case of two repositories: mozilla-central and autoland. You make autoland use mozilla-central as a shared repository. Now, you push something new to autoland, it's stored in the autoland datastore. Eventually, you merge to mozilla-central. Congratulations, it's now in both datastores, and you'd need to clean-up autoland if you wanted to avoid the duplication.

Now, you'd think mozilla-unified would solve these issues, and it would... to some extent. Because that wouldn't cover user repositories and project branches briefly mentioned above, which in GitHub parlance would be considered as Forks. So you'd want a mega global datastore shared by all repositories, and repositories would need to only expose what they really contain. Does Mercurial support that? I don't think so (okay, I'll give you that: even if it doesn't, it could, but that's extra work). And since we're talking about a transition to Git, does Git support that? You may have read about how you can link to a commit from a fork and make-pretend that it comes from the main repository on GitHub? At least, it shows a warning, now. That's essentially the architectural reason why. So the actual answer is that Git doesn't support it out of the box, but GitHub has some backend magic to handle it somehow (and hopefully, other things like Gitea, Girocco, Gitlab, etc. have something similar).

Now, to come back to the size of the repository. A repository is not a static file. It's a server with which you negotiate what you have against what it has that you want. Then the server bundles what you asked for based on what you said you have. Or in the opposite direction, you negotiate what you have that it doesn't, you send it, and the server incorporates what you sent it. Fortunately the latter is less frequent and requires authentication. But the former is more frequent and CPU intensive. Especially when pulling a large number of changesets, which, incidentally, cloning is.

"But there is a solution for clones" you might say, which is true. That's clonebundles, which offload the CPU intensive part of cloning to a single job scheduled regularly. Guess who implemented it? Mozilla. But that only covers the cloning part. We actually had laid the ground to support offloading large incremental updates and split clones, but that never materialized. Even with all that, that still leaves you with a server that can display file contents, diffs, blames, provide zip archives of a revision, and more, all of which are CPU intensive in their own way.

And these endpoints are regularly abused, and cause extra load to your servers, yes plural, because of course a single server won't handle the load for the number of users of your big repositories. And because your endpoints are abused, you have to close some of them. And I'm not mentioning the Try repository with its tens of thousands of heads, which brings its own sets of problems (and it would have even more heads if we didn't fake-merge them once in a while).

Of course, all the above applies to Git (and it only gained support for something akin to clonebundles last year). So, when the Firefox OS project was stopped, there wasn't much motivation to continue supporting our own Git server, Mercurial still being the official point of entry, and git.mozilla.org was shut down in 2016.

The growing difficulty of maintaining the status quo

Slowly, but steadily in more recent years, as new tooling was added that needed some input from the source code manager, support for Git was more and more consistently added. But at the same time, as people left for other endeavors and weren't necessarily replaced, or more recently with layoffs, resources allocated to such tooling have been spread thin.

Meanwhile, the repository growth didn't take a break, and the Try repository was becoming an increasing pain, with push times quite often exceeding 10 minutes. The ongoing work to move Try pushes to Lando will hide the problem under the rug, but the underlying problem will still exist (although the last version of Mercurial seems to have improved things).

On the flip side, more and more people have been relying on Git for Firefox development, to my own surprise, as I didn't really push for that to happen. It just happened organically, by ways of git-cinnabar existing, providing a compelling experience to those who prefer Git, and, I guess, word of mouth. I was genuinely surprised when I recently heard the use of Git among moz-phab users had surpassed a third. I did, however, occasionally orient people who struggled with Mercurial and said they were more familiar with Git, towards git-cinnabar. I suspect there's a somewhat large number of people who never realized Git was a viable option.

But that, on its own, can come with its own challenges: if you use git-cinnabar without being backed by gecko-dev, you'll have a hard time sharing your branches on GitHub, because you can't push to a fork of gecko-dev without pushing your entire local repository, as they have different commit histories. And switching to gecko-dev when you weren't already using it requires some extra work to rebase all your local branches from the old commit history to the new one.

Clone times with git-cinnabar have also started to go a little out of hand in the past few years, but this was mitigated in a similar manner as with the Mercurial cloning problem: with static files that are refreshed regularly. Ironically, that made cloning with git-cinnabar faster than cloning with Mercurial. But generating those static files is increasingly time-consuming. As of writing, generating those for mozilla-unified takes close to 7 hours. I was predicting clone times over 10 hours "in 5 years" in a post from 4 years ago, I wasn't too far off. With exponential growth, it could still happen, although to be fair, CPUs have improved since. I will explore the performance aspect in a subsequent blog post, alongside the upcoming release of git-cinnabar 0.7.0-b1. I don't even want to check how long it now takes with hg-git or git-remote-hg (they were already taking more than a day when git-cinnabar was taking a couple hours).

I suppose it's about time that I clarify that git-cinnabar has always been a side-project. It hasn't been part of my duties at Mozilla, and the extent to which Mozilla supports git-cinnabar is in the form of taskcluster workers on the community instance for both git-cinnabar CI and generating those clone bundles. Consequently, that makes the above git-cinnabar specific issues a Me problem, rather than a Mozilla problem.

Taking the leap

I can't talk for the people who made the proposal to move to Git, nor for the people who put a green light on it. But I can at least give my perspective.

Developers have regularly asked why Mozilla was still using Mercurial, but I think it was the first time that a formal proposal was laid out. And it came from the Engineering Workflow team, responsible for issue tracking, code reviews, source control, build and more.

It's easy to say "Mozilla should have chosen Git in the first place", but back in 2007, GitHub wasn't there, Bitbucket wasn't there, and all the available options were rather new (especially compared to the then 21 years-old CVS). I think Mozilla made the right choice, all things considered. Had they waited a couple years, the story might have been different.

You might say that Mozilla stayed with Mercurial for so long because of the sunk cost fallacy. I don't think that's true either. But after the biggest Mercurial repository hosting service turned off Mercurial support, and the main contributor to Mercurial going their own way, it's hard to ignore that the landscape has evolved.

And the problems that we regularly encounter with the Mercurial servers are not going to get any better as the repository continues to grow. As far as I know, all the Mercurial repositories bigger than Mozilla's are... not using Mercurial. Google has its own closed-source server, and Facebook has another of its own, and it's not really public either. With resources spread thin, I don't expect Mozilla to be able to continue supporting a Mercurial server indefinitely (although I guess Octobus could be contracted to give a hand, but is that sustainable?).

Mozilla, being a champion of Open Source, also doesn't live in a silo. At some point, you have to meet your contributors where they are. And the Open Source world is now majoritarily using Git. I'm sure the vast majority of new hires at Mozilla in the past, say, 5 years, know Git and have had to learn Mercurial (although they arguably didn't need to). Even within Mozilla, with thousands(!) of repositories on GitHub, Firefox is now actually the exception rather than the norm. I should even actually say Desktop Firefox, because even Mobile Firefox lives on GitHub (although Fenix is moving back in together with Desktop Firefox, and the timing is such that that will probably happen before Firefox moves to Git).

Heck, even Microsoft moved to Git!

With a significant developer base already using Git thanks to git-cinnabar, and all the constraints and problems I mentioned previously, it actually seems natural that a transition (finally) happens. However, had git-cinnabar or something similarly viable not existed, I don't think Mozilla would be in a position to take this decision. On one hand, it probably wouldn't be in the current situation of having to support both Git and Mercurial in the tooling around Firefox, nor the resource constraints related to that. But on the other hand, it would be farther from supporting Git and being able to make the switch in order to address all the other problems.

But... GitHub?

I hope I made a compelling case that hosting is not as simple as it can seem, at the scale of the Firefox repository. It's also not Mozilla's main focus. Mozilla has enough on its plate with the migration of existing infrastructure that does rely on Mercurial to understandably not want to figure out the hosting part, especially with limited resources, and with the mixed experience hosting both Mercurial and git has been so far.

After all, GitHub couldn't even display things like the contributors' graph on gecko-dev until recently, and hosting is literally their job! They still drop the ball on large blames (thankfully we have searchfox for those).

Where does that leave us? Gitlab? For those criticizing GitHub for being proprietary, that's probably not open enough. Cloud Source Repositories? "But GitHub is Microsoft" is a complaint I've read a lot after the announcement. Do you think Google hosting would have appealed to these people? Bitbucket? I'm kind of surprised it wasn't in the list of providers that were considered, but I'm also kind of glad it wasn't (and I'll leave it at that).

I think the only relatively big hosting provider that could have made the people criticizing the choice of GitHub happy is Codeberg, but I hadn't even heard of it before it was mentioned in response to Mozilla's announcement. But really, with literal thousands of Mozilla repositories already on GitHub, with literal tens of millions repositories on the platform overall, the pragmatic in me can't deny that it's an attractive option (and I can't stress enough that I wasn't remotely close to the room where the discussion about what choice to make happened).

"But it's a slippery slope". I can see that being a real concern. LLVM also moved its repository to GitHub (from a (I think) self-hosted Subversion server), and ended up moving off Bugzilla and Phabricator to GitHub issues and PRs four years later. As an occasional contributor to LLVM, I hate this move. I hate the GitHub review UI with a passion.

At least, right now, GitHub PRs are not a viable option for Mozilla, for their lack of support for security related PRs, and the more general shortcomings in the review UI. That doesn't mean things won't change in the future, but let's not get too far ahead of ourselves. The move to Git has just been announced, and the migration has not even begun yet. Just because Mozilla is moving the Firefox repository to GitHub doesn't mean it's locked in forever or that all the eggs are going to be thrown into one basket. If bridges need to be crossed in the future, we'll see then.

So, what's next?

The official announcement said we're not expecting the migration to really begin until six months from now. I'll swim against the current here, and say this: the earlier you can switch to git, the earlier you'll find out what works and what doesn't work for you, whether you already know Git or not.

While there is not one unique workflow, here's what I would recommend anyone who wants to take the leap off Mercurial right now:

  • Make sure git is installed. Chances are you already have it.

  • Install git-cinnabar where mach bootstrap would install it.

    $ mkdir -p ~/.mozbuild/git-cinnabar
    $ cd ~/.mozbuild/git-cinnabar
    $ curl -sOL https://raw.githubusercontent.com/glandium/git-cinnabar/master/download.py
    $ python3 download.py && rm download.py
  • Add git-cinnabar to your PATH. Make sure to also set that wherever you keep your PATH up-to-date (.bashrc or wherever else).

    $ PATH=$PATH:$HOME/.mozbuild/git-cinnabar
  • Enter your mozilla-central or mozilla-unified Mercurial working copy, we'll do an in-place conversion, so that you don't need to move your mozconfigs, objdirs and what not.

  • Initialize the git repository from GitHub.

    $ git init
    $ git remote add origin https://github.com/mozilla/gecko-dev
    $ git remote update origin
  • Switch to a Mercurial remote.

    $ git remote set-url origin hg::https://hg.mozilla.org/mozilla-unified
    $ git config --local remote.origin.cinnabar-refs bookmarks
    $ git remote update origin --prune
  • Fetch your local Mercurial heads.

    $ git -c cinnabar.refs=heads fetch hg::$PWD refs/heads/default/*:refs/heads/hg/*

    This will create a bunch of hg/<sha1> local branches, not all relevant to you (some come from old branches on mozilla-central). Note that if you're using Mercurial MQ, this will not pull your queues, as they don't exist as heads in the Mercurial repo. You'd need to apply your queues one by one and run the command above for each of them.
    Or, if you have bookmarks for your local Mercurial work, you can use this instead:

    $ git -c cinnabar.refs=bookmarks fetch hg::$PWD refs/heads/*:refs/heads/hg/*

    This will create hg/<bookmark_name> branches.

  • Now, make git know what commit your working tree is on.

    $ git reset $(git cinnabar hg2git $(hg log -r . -T '{node}'))

    This will take a little moment because Git is going to scan all the files in the tree for the first time. On the other hand, it won't touch their content or timestamps, so if you had a build around, it will still be valid, and mach build won't rebuild anything it doesn't have to.

As there is no one-size-fits-all workflow, I won't tell you how to organize yourself from there. I'll just say this: if you know the Mercurial sha1s of your previous local work, you can create branches for them with:

$ git branch <branch_name> $(git cinnabar hg2git <hg_sha1>)

At this point, you should have everything available on the Git side, and you can remove the .hg directory. Or move it into some empty directory somewhere else, just in case. But don't leave it here, it will only confuse the tooling. Artifact builds WILL be confused, though, and you'll have to ./mach configure before being able to do anything. You may also hit bug 1865299 if your working tree is older than this post.

If you have any problem or question, you can ping me on #git-cinnabar or #git on Matrix. I'll put the instructions above somewhere on wiki.mozilla.org, and we can collaboratively iterate on them.

Now, what the announcement didn't say is that the Git repository WILL NOT be gecko-dev, doesn't exist yet, and WON'T BE COMPATIBLE (trust me, it'll be for the better). Why did I make you do all the above, you ask? Because that won't be a problem. I'll have you covered, I promise. The upcoming release of git-cinnabar 0.7.0-b1 will have a way to smoothly switch between gecko-dev and the future repository (incidentally, that will also allow to switch from a pure git-cinnabar clone to a gecko-dev one, for the git-cinnabar users who have kept reading this far).

What about git-cinnabar?

With Mercurial going the way of the dodo at Mozilla, my own need for git-cinnabar will vanish. Legitimately, this begs the question whether it will still be maintained.

I can't answer for sure. I don't have a crystal ball. However, the needs of the transition itself will motivate me to finish some long-standing things (like finalizing the support for pushing merges, which is currently behind an experimental flag) or implement some missing features (support for creating Mercurial branches).

Git-cinnabar started as a Python script, it grew a sidekick implemented in C, which then incorporated some Rust, which then cannibalized the Python script and took its place. It is now close to 90% Rust, and 10% C (if you don't count the code from Git that is statically linked to it), and has sort of become my Rust playground (it's also, I must admit, a mess, because of its history, but it's getting better). So the day to day use with Mercurial is not my sole motivation to keep developing it. If it were, it would stay stagnant, because all the features I need are there, and the speed is not all that bad, although I know it could be better. Arguably, though, git-cinnabar has been relatively stagnant feature-wise, because all the features I need are there.

So, no, I don't expect git-cinnabar to die along Mercurial use at Mozilla, but I can't really promise anything either.

Final words

That was a long post. But there was a lot of ground to cover. And I still skipped over a bunch of things. I hope I didn't bore you to death. If I did and you're still reading... what's wrong with you? ;)

So this is the end of Mercurial at Mozilla. So long, and thanks for all the fish. But this is also the beginning of a transition that is not easy, and that will not be without hiccups, I'm sure. So fasten your seatbelts (plural), and welcome the change.

To circle back to the clickbait title, did I really kill Mercurial at Mozilla? Of course not. But it's like I stumbled upon a few sparks and tossed a can of gasoline on them. I didn't start the fire, but I sure made it into a proper bonfire... and now it has turned into a wildfire.

And who knows? 15 years from now, someone else might be looking back at how Mozilla picked Git at the wrong time, and that, had we waited a little longer, we would have picked some yet to come new horse. But hey, that's the tech cycle for you.

21 November, 2023 07:49PM by glandium

hackergotchi for Joey Hess

Joey Hess

attribution armored code

Attribution of source code has been limited to comments, but a deeper embedding of attribution into code is possible. When an embedded attribution is removed or is incorrect, the code should no longer work. I've developed a way to do this in Haskell that is lightweight to add, but requires more work to remove than seems worthwhile for someone who is training an LLM on my code. And when it's not removed, it invites LLM hallucinations of broken code.

I'm embedding attribution by defining a function like this in a module, which uses an author function I wrote:

import Author

copyright = author JoeyHess 2023

One way to use is it this:

shellEscape f = copyright ([q] ++ escaped ++ [q])

It's easy to mechanically remove that use of copyright, but less so ones like these, where various changes have to be made to the code after removing it to keep the code working.

| c == ' ' && copyright = (w, cs)

| isAbsolute b' = not copyright

b <- copyright =<< S.hGetSome h 80

(word, rest) = findword "" s & copyright

This function which can be used in such different ways is clearly polymorphic. That makes it easy to extend it to be used in more situations. And hard to mechanically remove it, since type inference is needed to know how to remove a given occurance of it. And in some cases, biographical information as well..

| otherwise = False || author JoeyHess 1492

Rather than removing it, someone could preprocess my code to rename the function, modify it to not take the JoeyHess parameter, and have their LLM generate code that includes the source of the renamed function. If it wasn't clear before that they intended their LLM to violate the license of my code, manually erasing my name from it would certainly clarify matters! One way to prevent against such a renaming is to use different names for the copyright function in different places.

The author function takes a copyright year, and if the copyright year is not in a particular range, it will misbehave in various ways (wrong values, in some cases spinning and crashing). I define it in each module, and have been putting a little bit of math in there.

copyright = author JoeyHess (40*50+10)
copyright = author JoeyHess (101*20-3)
copyright = author JoeyHess (2024-12)
copyright = author JoeyHess (1996+14)
copyright = author JoeyHess (2000+30-20)

The goal of that is to encourage LLMs trained on my code to hallucinate other numbers, that are outside the allowed range.

I don't know how well all this will work, but it feels like a start, and easy to elaborate on. I'll probably just spend a few minutes adding more to this every time I see another too many fingered image or read another breathless account of pair programming with AI that's much longer and less interesting than my daily conversations with the Haskell type checker.

The code clutter of scattering copyright around in useful functions is mildly annoying, but it feels worth it. As a programmer of as niche a language as Haskell, I'm keenly aware that there's a high probability that code I write to do a particular thing will be one of the few implementations in Haskell of that thing. Which means that likely someone asking an LLM to do that in Haskell will get at best a lightly modified version of my code.

For a real life example of this happening (not to me), see this blog post where they asked ChatGPT for a HTTP server. This stackoverflow question is very similar to ChatGPT's response. Where did the person posting that question come up with that? Well, they were reading intro to WAI documentation like this example and tried to extend the example to do something useful. If ChatGPT did anything at all transformative to that code, it involved splicing in the "Hello world" and port number from the example code into the stackoverflow question.

(Also notice that the blog poster didn't bother to track down this provenance, although it's not hard to find. Good example of the level of critical thinking and hype around "AI".)

By the way, back in 2021 I developed another way to armor code against appropriation by LLMs. See a bitter pill for Microsoft Copilot. That method is considerably harder to implement, and clutters the code more, but is also considerably stealthier. Perhaps it is best used sparingly, and this new method used more broadly. This new method should also be much easier to transfer to languages other than Haskell.

If you'd like to do this with your own code, I'd encourage you to take a look at my implementation in Author.hs, and then sit down and write your own from scratch, which should be easy enough. Of course, you could copy it, if its license is to your liking and my attribution is preserved.

This was sponsored by Mark Reidenbach, unqueued, Lawrence Brogan, and Graham Spencer on Patreon.

21 November, 2023 06:00PM

Russ Allbery

Review: Thud!

Review: Thud!, by Terry Pratchett

Series: Discworld #34
Publisher: Harper
Copyright: October 2005
Printing: November 2014
ISBN: 0-06-233498-0
Format: Mass market
Pages: 434

Thud! is the 34th Discworld novel and the seventh Watch novel. It is partly a sequel to The Fifth Elephant, partly a sequel to Night Watch, and references many of the previous Watch novels. This is not a good place to start.

Dwarfs and trolls have a long history of conflict, as one might expect between a race of creatures who specialize in mining and a race of creatures whose vital organs are sometimes the targets of that mining. The first battle of Koom Valley was the place where that enmity was made concrete and given a symbol. Now that there are large dwarf and troll populations in Ankh-Morpork, the upcoming anniversary of that battle is the excuse for rising tensions. Worse, Grag Hamcrusher, a revered deep-down dwarf and a dwarf supremacist, is giving incendiary speeches about killing all trolls and appears to be tunneling under the city.

Then whispers run through the city's dwarfs that Hamcrusher has been murdered by a troll.

Vimes has no patience for racial tensions, or for the inspection of the Watch by one of Vetinari's excessively competent clerks, or the political pressure to add a vampire to the Watch over his prejudiced objections. He was already grumpy before the murder and is in absolutely no mood to be told by deep-down dwarfs who barely believe that humans exist that the murder of a dwarf underground is no affair of his.

Meanwhile, The Battle of Koom Valley by Methodia Rascal has been stolen from the Ankh-Morpork Royal Art Museum, an impressive feat given that the painting is ten feet high and fifty feet long. It was painted in impressive detail by a madman who thought he was a chicken, and has been the spark for endless theories about clues to some great treasure or hidden knowledge, culminating in the conspiratorial book Koom Valley Codex. But the museum prides itself on allowing people to inspect and photograph the painting to their heart's content and was working on a new room to display it. It's not clear why someone would want to steal it, but Colon and Nobby are on the case.

This was a good time to read this novel. Sadly, the same could be said of pretty much every year since it was written.

"Thud" in the title is a reference to Hamcrusher's murder, which was supposedly done by a troll club that was found nearby, but it's also a reference to a board game that we first saw in passing in Going Postal. We find out a lot more about Thud in this book. It's an asymmetric two-player board game that simulates a stylized battle between dwarf and troll forces, with one player playing the trolls and the other playing the dwarfs. The obvious comparison is to chess, but a better comparison would be to the old Steve Jackson Games board game Ogre, which also featured asymmetric combat mechanics. (I'm sure there are many others.) This board game will become quite central to the plot of Thud! in ways that I thought were ingenious.

I thought this was one of Pratchett's best-plotted books to date. There are a lot of things happening, involving essentially every member of the Watch that we've met in previous books, and they all matter and I was never confused by how they fit together. This book is full of little callbacks and apparently small things that become important later in a way that I found delightful to read, down to the children's book that Vimes reads to his son and that turns into the best scene of the book. At this point in my Discworld read-through, I can see why the Watch books are considered the best sub-series. It feels like Pratchett kicks the quality of writing up a notch when he has Vimes as a protagonist.

In several books now, Pratchett has created a villain by taking some human characteristic and turning it into an external force that acts on humans. (See, for instance the Gonne in Men at Arms, or the hiver in A Hat Full of Sky.) I normally do not like this plot technique, both because I think it lets humans off the hook in a way that cheapens the story and because this type of belief has a long and bad reputation in religions where it is used to dodge personal responsibility and dehumanize one's enemies. When another of those villains turned up in this book, I was dubious. But I think Pratchett pulls off this type of villain as well here as I've seen it done. He lifts up a facet of humanity to let the reader get a better view, but somehow makes it explicit that this is concretized metaphor. This force is something people create and feed and choose and therefore are responsible for.

The one sour note that I do have to complain about is that Pratchett resorts to some cheap and annoying "men are from Mars, women are from Venus" nonsense, mostly around Nobby's subplot but in a few other places (Sybil, some of Angua's internal monologue) as well. It's relatively minor, and I might let it pass without grumbling in other books, but usually Pratchett is better on gender than this. I expected better and it got under my skin.

Otherwise, though, this was a quietly excellent book. It doesn't have the emotional gut punch of Night Watch, but the plotting is superb and the pacing is a significant improvement over The Fifth Elephant. The parody is of The Da Vinci Code, which is both more interesting than Pratchett's typical movie parodies and delightfully subtle. We get more of Sybil being a bad-ass, which I am always here for. There's even some lovely world-building in the form of dwarven Devices.

I love how Pratchett has built Vimes up into one of the most deceptively heroic figures on Discworld, but also shows all of the support infrastructure that ensures Vimes maintain his principles. On the surface, Thud! has a lot in common with Vimes's insistently moral stance in Jingo, but here it is more obvious how Vimes's morality happens in part because his wife, his friends, and his boss create the conditions for it to thrive.

Highly recommended to anyone who has gotten this far.

Rating: 9 out of 10

21 November, 2023 03:46AM

November 20, 2023

Arturo Borrero González

New job at Spryker

Post logo

Last month, in October 2023, I started a new job as a Senior Site Reliability Engineer at the Germany-headquartered technology company Spryker. They are primarily focused on e-commerce and infrastructure businesses.

I joined this company with excitement and curiosity, as I would be working with a new technology stack: AWS and Terraform. I had not been directly exposed to them in the past, but I was aware of the vast industry impact of both.

Suddenly, things like PXE boot, NIC firmware, and Linux kernel upgrades are mostly AWS problems.

This is a full-time, 100% remote job position. I’m writing this post one month into the new position, and all I can say is that the onboarding was smooth, and I found some good people in my team.

Prior to joining Spryker, I was a Senior SRE at the Wikimedia Cloud Services team at the Wikimedia Foundation. I had been there since 2017, for 6 years. It was a privilege working there.

20 November, 2023 07:44AM

Russ Allbery

Review: The Exiled Fleet

Review: The Exiled Fleet, by J.S. Dewes

Series: Divide #2
Publisher: Tor
Copyright: 2021
ISBN: 1-250-23635-5
Format: Kindle
Pages: 421

The Exiled Fleet is far-future interstellar military SF. It is a direct sequel to The Last Watch. You don't want to start here.

The Last Watch took a while to get going, but it ended with some fascinating world-building and a suitably enormous threat. I was hoping Dewes would carry that momentum into the second book. I was disappointed; instead, The Exiled Fleet starts with interpersonal angst and wallowing and takes an annoyingly long time to build up narrative tension again.

The world-building of the first book looked outward, towards aliens and strange technology and stranger physics, while setting up contributing problems on the home front. The Exiled Fleet pivots inwards, both in terms of world-building and in terms of character introspection. Neither of those worked as well for me.

There's nothing wrong with the revelations here about human power structures and the politics that the Sentinels have been missing at the edge of space, but it also felt like a classic human autocracy without much new to offer in either wee thinky bits or plot structure. We knew most of shape from the start of the first book: Cavalon's grandfather is evil, human society is run as an oligarchy, and everything is trending authoritarian. Once the action started, I was entertained but not gripped the way that I was when reading The Last Watch. Dewes makes a brief attempt to tap into the morally complex question of the military serving as a brake on tyranny, but then does very little with it. Instead, everything is excessively personal, turning the political into less of a confrontation of ideologies or ethics and more a story of family abuse and rebellion.

There is even more psychodrama in this book than there was in the previous book. I found it exhausting. Rake is barely functional after the events of the previous book and pushing herself way too hard at the start of this one. Cavalon regresses considerably and starts falling apart again. There's a lot of moping, a lot of angst, and a lot of characters berating themselves and occasionally each other. It was annoying enough that I took a couple of weeks break from this book in the middle before I could work up the enthusiasm to finish it.

Some of this is personal preference. My favorite type of story is competence porn: details about something esoteric and satisfyingly complex, a challenge to overcome, and a main character who deploys their expertise to overcome that challenge in a way that shows they generally have their shit together. I can enjoy other types of stories, but that's the story I'll keep reaching for.

Other people prefer stories about fuck-ups and walking disasters, people who barely pull together enough to survive the plot (or sometimes not even that). There's nothing wrong with that, and neither approach is right or wrong, but my tolerance for that story is usually lot lower. I think Dewes is heading towards the type of story in which dysfunctional characters compensate for each other's flaws in order to keep each other going, and intellectually I can see the appeal. But it's not my thing, and when the main characters are falling apart and the supporting characters project considerably more competence, I wish the story had different protagonists.

It didn't help that this is in theory military SF, but Dewes does not seem to want to deploy any of the support framework of the military to address any of her characters' problems. This book is a lot of Rake and Cavalon dragging each other through emotional turmoil while coming to terms with Cavalon's family. I liked their dynamic in the first book when it felt more like Rake showing leadership skills. Here, it turns into something closer to found family in ways that seemed wildly inconsistent with the military structure, and while I'm normally not one to defend hierarchical discipline, I felt like Rake threw out the only structure she had to handle the thousands of other people under her command and started winging it based on personal friendship. If this were a small commercial crew, sure, fine, but Rake has a personal command responsibility that she obsessively angsts about and yet keeps abandoning.

I realize this is probably another way to complain that I wanted competence porn and got barely-functional fuck-ups.

The best parts of this series are the strange technologies and the aliens, and they are again the best part of this book. There was a truly great moment involving Viator technology that I found utterly delightful, and there was an intriguing setup for future books that caught my attention. Unfortunately, there were also a lot of deus ex machina solutions to problems, both from convenient undisclosed character backstories and from alien tech. I felt like the characters had to work satisfyingly hard for their victories in the first book; here, I felt like Dewes kept having issues with her characters being at point A and her plot at point B and pulling some rabbit out of the hat to make the plot work. This unfortunately undermined the cool factor of the world-building by making its plot device aspects a bit too obvious.

This series also turns out not to be a duology (I have no idea why I thought it would be). By the end of The Exiled Fleet, none of the major political or world-building problems have been resolved. At best, the characters are in a more stable space to start being proactive. I'm cautiously optimistic that could mean the series would turn into the type of story I was hoping for, but I'm worried that Dewes is interested in writing a different type of character story than I am interested in reading. Hopefully there will be some clues in the synopsis of the (as yet unannounced) third book.

I thought The Last Watch had some first-novel problems but was worth reading. I am much more reluctant to recommend The Exiled Fleet, or the series as a whole given that it is incomplete. Unless you like dysfunctional characters, proceed with caution.

Rating: 5 out of 10

20 November, 2023 03:51AM

November 18, 2023

hackergotchi for Bits from Debian

Bits from Debian

Debian Events: MiniDebConfCambridge-2023


Next week the #MiniDebConfCambridge takes place in Cambridge, UK. This event will run from Thursday 23 to Sunday 26 November 2023.

The 4 days of the MiniDebConf include a Mini-DebCamp and of course the main Conference talks, BoFs, meets, and Sprints.

We give thanks to our partners and sponsors for this event

Arm - Building the Future of Computing

Codethink - Open Source System Software Experts

pexip - Powering video everywhere

Please see the MiniDebConfCambridge page more for information regarding Travel documentation, Accomodation, Meal planning, the full conference schedule, and yes, even parking.

We hope to see you there!

18 November, 2023 10:00AM by The Debian Publicity Team

November 17, 2023

hackergotchi for Jonathan Dowland

Jonathan Dowland

HLedger, regex matches and field assignments

I've finally landed a patch/feature for HLedger I've been working on-and-off (mostly off) since around March.

HLedger has a powerful CSV importer which you configure with a set of rules. Rules consist of conditional matchers (does field X in this CSV row match this regular expression?) and field assignments (set the resulting transaction's account to Y).

motivating problem 1

Here's an example of one of my rules for handling credit card repayments. This rule is applied when I import a CSV for my current account, which pays the credit card:

    account2 liabilities:amex

This results in a ledger entry like the following

    assets:current          £- 6.66
    liabilities:amex        £  6.66

My current account statements cover calendar months. My credit card period spans mid-month to mid-month. I pay it off by direct debit, which comes out after the credit card period, towards the very end of the calendar month. That transaction falls roughly halfway through the next credit card period.

On my credit card statements, that repayment is "warped" to the start of the list of transactions, clearing the outstanding balance from the previous period.

When I import my credit card data to HLedger, I want to compare the result against a PDF statement to make sure my ledger matches reality. The repayment "warping" makes this awkward, because it means the balance for roughly half the new transactions (those that fall before the real-date of the repayment) don't match up.

motivating problem 2

I start new ledger files each year. I need to import the closing balances from the previous year to the next, which I do by exporting the final balance from the previous year in CSV and importing that into the new ledgers in the usual way.

Between 2022 and 2023 I changed the scheme I use for account names so I need to translate between the old and the new in the opening balances. I couldn't think of a way of achieving this in the import rules (besides writing a bespoke rule for every possible old account name) so I abused another HLedger feature instead, HLedger aliases. For example I added this alias in my family ledger file for 2023

alias /^family:(.*)/ = \1

These are ugly and I'd prefer to get rid of them.

regex match groups

A common feature of regular expressions is defining match groups which can be referenced elsewhere, such as on the far-side of a substitution. I added match group support to HLedger's field assignments.

addressing date warping

Here's an updated version rule from the first motivating problem:

& %date (..)/(..)/(....)
    account2 liabilities:amex
    comment2 date:\3-\2-16

We now match on on extra date field, and surround the day/month/year components with parentheses to define match groups. We add a second field assignment too, setting the second posting's "comment" field to a string which, once the match groups are interpolated, instructs HLedger to do date warping (I wrote about this in date warping in HLedger)

The new transaction looks like this:

    assets:current          £- 6.66
    liabilities:amex        £  6.66 ; date:2023-10-16

getting rid of aliases

In the second problem, I can strip off the unwanted account name prefixes at CSV import time, with rules like this

if %account2 ^family:(.*)$
    account2 \1


This stuff landed a week ago in early November, and is not yet in a Hledger release.

17 November, 2023 09:39PM

denver luna

picture of the denver luna record on a turntable

I haven't done one of these in a while!

Denver Luna is the latest single from Underworld, here on a pink 12" vinyl. The notable thing about this release was it was preceded by an "acapella" mix, consisting of just Karl Hyde's vocals: albeit treated and layered. Personally I prefer the "main" single mix, which calls back to their biggest hits. The vinyl also features an instrumental take, which is currently unavailable in any other formats.

The previous single (presumably both from a forthcoming album) was and the colour red.

In this crazy world we live in, this was limited to 1,000 copies. Flippers have sold 4 on eBay already, at between £ 55 and £ 75.

17 November, 2023 01:59PM

November 16, 2023

Dimitri John Ledkov

Ubuntu 23.10 significantly reduces the installed kernel footprint

Photo by Pixabay

Ubuntu systems typically have up to 3 kernels installed, before they are auto-removed by apt on classic installs. Historically the installation was optimized for metered download size only. However, kernel size growth and usage no longer warrant such optimizations. During the 23.10 Mantic Minatour cycle, I led a coordinated effort across multiple teams to implement lots of optimizations that together achieved unprecedented install footprint improvements.

Given a typical install of 3 generic kernel ABIs in the default configuration on a regular-sized VM (2 CPU cores 8GB of RAM) the following metrics are achieved in Ubuntu 23.10 versus Ubuntu 22.04 LTS:

  • 2x less disk space used (1,417MB vs 2,940MB, including initrd)

  • 3x less peak RAM usage for the initrd boot (68MB vs 204MB)

  • 0.5x increase in download size (949MB vs 600MB)

  • 2.5x faster initrd generation (4.5s vs 11.3s)

  • approximately the same total time (103s vs 98s, hardware dependent)

For minimal cloud images that do not install either linux-firmware or modules extra the numbers are:

  • 1.3x less disk space used (548MB vs 742MB)

  • 2.2x less peak RAM usage for initrd boot (27MB vs 62MB)

  • 0.4x increase in download size (207MB vs 146MB)

Hopefully, the compromise of download size, relative to the disk space & initrd savings is a win for the majority of platforms and use cases. For users on extremely expensive and metered connections, the likely best saving is to receive air-gapped updates or skip updates.

This was achieved by precompressing kernel modules & firmware files with the maximum level of Zstd compression at package build time; making actual .deb files uncompressed; assembling the initrd using split cpio archives - uncompressed for the pre-compressed files, whilst compressing only the userspace portions of the initrd; enabling in-kernel module decompression support with matching kmod; fixing bugs in all of the above, and landing all of these things in time for the feature freeze. Whilst leveraging the experience and some of the design choices implementations we have already been shipping on Ubuntu Core. Some of these changes are backported to Jammy, but only enough to support smooth upgrades to Mantic and later. Complete gains are only possible to experience on Mantic and later.

The discovered bugs in kernel module loading code likely affect systems that use LoadPin LSM with kernel space module uncompression as used on ChromeOS systems. Hopefully, Kees Cook or other ChromeOS developers pick up the kernel fixes from the stable trees. Or you know, just use Ubuntu kernels as they do get fixes and features like these first.

The team that designed and delivered these changes is large: Benjamin Drung, Andrea Righi, Juerg Haefliger, Julian Andres Klode, Steve Langasek, Michael Hudson-Doyle, Robert Kratky, Adrien Nader, Tim Gardner, Roxana Nicolescu - and myself Dimitri John Ledkov ensuring the most optimal solution is implemented, everything lands on time, and even implementing portions of the final solution.

Hi, It's me, I am a Staff Engineer at Canonical and we are hiring https://canonical.com/careers.

Lots of additional technical details and benchmarks on a huge range of diverse hardware and architectures, and bikeshedding all the things below:

For questions and comments please post to Kernel section on Ubuntu Discourse.

16 November, 2023 10:45AM by Dimitri John Ledkov (noreply@blogger.com)

hackergotchi for Martin-&#201;ric Racine

Martin-Éric Racine

dhcpcd almost ready to replace ISC dhclient in Debian

A lot of time has passed since my previous post on my work to make dhcpcd the drop-in replacement for the deprecated ISC dhclient a.k.a. isc-dhcp-client. Current status:

  • Upstream now regularly produces releases and with a smaller delta than before. This makes it easier to track possible breakage.
  • Debian packaging has essentially remained unchanged. A few Recommends were shuffled, but that's about it.
  • The only remaining bug is fixing the build for Hurd. Patches are welcome. Once that is fixed, bumping dhcpcd-base's priority to important is all that's left.

16 November, 2023 09:38AM by Martin-Éric (noreply@blogger.com)

November 14, 2023

John Goerzen

It’s More Important To Recognize What Direction People Are Moving Than Where They Are

I recently read a post on social media that went something like this (paraphrased):

“If you buy an EV, you’re part of the problem. You’re advancing car culture and are actively hurting the planet. The only ethical thing to do is ditch your cars and put all your effort into supporting transit. Anything else is worthless.”

There is some truth there; supporting transit in areas it makes sense is better than having more cars, even EVs. But of course the key here is in areas it makes sense.

My road isn’t even paved. I live miles from the nearest town. And get into the remote regions of the western USA and you’ll find people that live 40 miles from the nearest neighbor. There’s no realistic way that mass transit is ever going to be a thing in these areas. And even if it were somehow usable, sending buses over miles where nobody lives just to reach the few that are there will be worse than private EVs. And because I can hear this argument coming a mile away, no, it doesn’t make sense to tell these people to just not live in the country because the planet won’t support that anymore, because those people are literally the ones that feed the ones that live in the cities.

The funny thing is: the person that wrote that shares my concerns and my goals. We both care deeply about climate change. We both want positive change. And I, ahem, recently bought an EV.

I have seen this play out in so many ways over the last few years. Drive a car? Get yelled at. Support the wrong politician? Get a shunning. Not speak up loudly enough about the right politician? That’s a yellin’ too.

The problem is, this doesn’t make friends. In fact, it hurts the cause. It doesn’t recognize this truth:

It is more important to recognize what direction people are moving than where they are.

I support trains and transit. I’ve donated money and written letters to politicians. But, realistically, there will never be transit here. People in my county are unable to move all the way to transit. But what can we do? Plenty. We bought an EV. I’ve been writing letters to the board of our local electrical co-op advocating for relaxation of rules around residential solar installations, and am planning one myself. It may well be that our solar-powered transportation winds up having a lower carbon footprint than the poster’s transit use.

Pick your favorite cause. Whatever it is, consider your strategy: What do you do with someone that is very far away from you, but has taken the first step to move an inch in your direction? Do you yell at them for not being there instantly? Or do you celebrate that they have changed and are moving?

14 November, 2023 01:02AM by John Goerzen

November 11, 2023

hackergotchi for Gunnar Wolf

Gunnar Wolf

There once was a miniDebConf in Uruguay...

Meeting Debian people for having a good time together, for some good hacking, for learning, for teaching… Is always fun and welcome. It brings energy, life and joy. And this year, due to the six-months-long relocation my family and me decided to have to Argentina, I was unable to attend the real deal, DebConf23 at India.

And while I know DebConf is an experience like no other, this year I took part in two miniDebConfs. One I have already shared in this same blog: I was in MiniDebConf Tamil Nadu in India, followed by some days of pre-DebConf preparation and scouting in Kochi proper, where I got to interact with the absolutely great and loving team that prepared DebConf.

The other one is still ongoing (but close to finishing). Some months ago, I talked with Santiago Ruano, jokin as we were Spanish-speaking DDs announcing to the debian-private mailing list we’d be relocating to around Río de la Plata. And things… worked out normally: He has been for several months in Uruguay already, so he decided to rent a house for some days, and invite Debian people to do what we do best.

I left Paraná Tuesday night (and missed my online class at UNAM! Well, you cannot have everything, right?). I arrived early on Wednesday, and around noon came to the house of the keysigning (well, the place is properly called “Casa Key�, it’s a publicity agency that is also rented as a guesthouse in a very nice area of Montevideo, close to Nuevo Pocitos beach).

In case you don’t know it, Montevideo is on the Northern (or Eastern) shore of Río de la Plata, the widest river in the world (up to 300Km wide, with current and non-salty water). But most important for some Debian contributors: You can even come here by boat!

That first evening, we received Ilu, who was in Uruguay by chance for other issues (and we were very happy about it!) and a young and enthusiastic Uruguayan, Felipe, interested in getting involved in Debian. We spent the evening talking about life, the universe and everything… Which was a bit tiring, as I had to interface between Spanish and English, talking with two friends that didn’t share a common language 😉

On Thursday morning, I went out for an early walk at the beach. And lets say, if only just for the narrative, that I found a lost penguin emerging from Río de la Plata!

For those that don’t know (who’d be most of you, as he has not been seen at Debian events for 15 years), that’s Lisandro Damián Nicanor Pérez Meyer (or just lisandro), long-time maintainer of the Qt ecosystem, and one of our embedded world extraordinaires. So, after we got him dry and fed him fresh river fishes, he gave us a great impromptu talk about understanding and finding our way around the Device Tree Source files for development boards and similar machines, mostly in the ARM world.

From Argentina, we also had Emanuel (eamanu) crossing all the way from La Rioja.

I spent most of our first workday getting ① my laptop in shape to be useful as the driver for my online class on Thursday (which is no small feat — people that know the particularities of my much loved ARM-based laptop will understand), and ② running a set of tests again on my Raspberry Pi labortory, which I had not updated in several months.

I am happy to say we are also finally also building Raspberry images for Trixie (Debian 13, Testing)! Sadly, I managed to burn my USB-to-serial-console (UART) adaptor, and could neither test those, nor the oldstable ones we are still building (and will probably soon be dropped, if not for anything else, to save disk space).

We enjoyed a lot of socialization time. An important highlight of the conference for me was that we reconnected with a long-lost DD, Eduardo Trápani, and got him interested in getting involved in the project again! This second day, another local Uruguayan, Mauricio, joined us together with his girlfriend, Alicia, and Felipe came again to hang out with us. Sadly, we didn’t get photographic evidence of them (nor the permission to post it).

The nice house Santiago got for us was very well equipped for a miniDebConf. There were a couple of rounds of pool played by those that enjoyed it (I was very happy just to stand around, take some photos and enjoy the atmosphere and the conversation).

Today (Saturday) is the last full-house day of miniDebConf; tomorrow we will be leaving the house by noon. It was also a very productive day! We had a long, important conversation about an important discussion that we are about to present on debian-vote@lists.debian.org.

It has been a great couple of days! Sadly, it’s coming to an end… But this at least gives me the opportunity (and moral obligation!) to write a long blog post. And to thank Santiago for organizing this, and Debian, for sponsoring our trip, stay, foods and healthy enjoyment!

11 November, 2023 09:59PM

Matthias Klumpp

AppStream 1.0 released!

Today, 12 years after the meeting where AppStream was first discussed and 11 years after I released a prototype implementation I am excited to announce AppStream 1.0! 🎉🎉🎊

Check it out on GitHub, or get the release tarball or read the documentation or release notes! �

Some nostalgic memories

I was not in the original AppStream meeting, since in 2011 I was extremely busy with finals preparations and ball organization in high school, but I still vividly remember sitting at school in the students’ lounge during a break and trying to catch the really choppy live stream from the meeting on my borrowed laptop (a futile exercise, I watched parts of the blurry recording later).

I was extremely passionate about getting software deployment to work better on Linux and to improve the overall user experience, and spent many hours on the PackageKit IRC channel discussing things with many amazing people like Richard Hughes, Daniel Nicoletti, Sebastian Heinlein and others.

At the time I was writing a software deployment tool called Listaller – this was before Linux containers were a thing, and building it was very tough due to technical and personal limitations (I had just learned C!). Then in university, when I intended to recreate this tool, but for real and better this time as a new project called Limba, I needed a way to provide metadata for it, and AppStream fit right in! Meanwhile, Richard Hughes was tackling the UI side of things while creating GNOME Software and needed a solution as well. So I implemented a prototype and together we pretty much reshaped the early specification from the original meeting into what would become modern AppStream.

Back then I saw AppStream as a necessary side-project for my actual project, and didn’t even consider me as the maintainer of it for quite a while (I hadn’t been at the meeting afterall). All those years ago I had no idea that ultimately I was developing AppStream not for Limba, but for a new thing that would show up later, with an even more modern design called Flatpak. I also had no idea how incredibly complex AppStream would become and how many features it would have and how much more maintenance work it would be – and also not how ubiquitous it would become.

The modern Linux desktop uses AppStream everywhere now, it is supported by all major distributions, used by Flatpak for metadata, used for firmware metadata via Richard’s fwupd/LVFS, runs on every Steam Deck, can be found in cars and possibly many places I do not know yet.

What is new in 1.0?

API breaks

The most important thing that’s new with the 1.0 release is a bunch of incompatible changes. For the shared libraries, all deprecated API elements have been removed and a bunch of other changes have been made to improve the overall API and especially make it more binding-friendly. That doesn’t mean that the API is completely new and nothing looks like before though, when possible the previous API design was kept and some changes that would have been too disruptive have not been made. Regardless of that, you will have to port your AppStream-using applications. For some larger ones I already submitted patches to build with both AppStream versions, the 0.16.x stable series as well as 1.0+.

For the XML specification, some older compatibility for XML that had no or very few users has been removed as well. This affects for example release elements that reference downloadable data without an artifact block, which has not been supported for a while. For all of these, I checked to remove only things that had close to no users and that were a significant maintenance burden. So as a rule of thumb: If your XML validated with no warnings with the 0.16.x branch of AppStream, it will still be 100% valid with the 1.0 release.

Another notable change is that the generated output of AppStream 1.0 will always be 1.0 compliant, you can not make it generate data for versions below that (this greatly reduced the maintenance cost of the project).

Developer element

For a long time, you could set the developer name using the top-level developer_name tag. With AppStream 1.0, this is changed a bit. There is now a developer tag with a name child (that can be translated unless the translate="no" attribute is set on it). This allows future extensibility, and also allows to set a machine-readable id attribute in the developer element. This permits software centers to group software by developer easier, without having to use heuristics. If we decide to extend the developer information per-app in future, this is also now possible. Do not worry though the developer_name tag is also still read, so there is no high pressure to update. The old 0.16.x stable series also has this feature backported, so it can be available everywhere. Check out the developer tag specification for more details.

Scale factor for screenshots

Screenshot images can now have a scale attribute, to indicate an (integer) scaling factor to apply. This feature was a breaking change and therefore we could not have it for the longest time, but it is now available. Please wait a bit for AppStream 1.0 to become deployed more widespread though, as using it with older AppStream versions may lead to issues in some cases. Check out the screenshots tag specification for more details.

Screenshot environments

It is now possible to indicate the environment a screenshot was recorded in (GNOME, GNOME Dark, KDE Plasma, Windows, etc.) via an environment attribute on the respective screenshot tag. This was also a breaking change, so use it carefully for now! If projects want to, they can use this feature to supply dedicated screenshots depending on the environment the application page is displayed in. Check out the screenshots tag specification for more details.

References tag

This is a feature more important for the scientific community and scientific applications. Using the references tag, you can associate the AppStream component with a DOI (Digital object identifier) or provide a link to a CFF file to provide citation information. It also allows to link to other scientific registries. Check out the references tag specification for more details.

Release tags

Releases can have tags now, just like components. This is generally not a feature that I expect to be used much, but in certain instances it can become useful with a cooperating software center, for example to tag certain releases as long-term supported versions.

Multi-platform support

Thanks to the interest and work of many volunteers, AppStream (mostly) runs on FreeBSD now, a NetBSD port exists, support for macOS was written and a Windows port is on its way! Thank you to everyone working on this 🙂

Better compatibility checks

For a long time I thought that the AppStream library should just be a thin layer above the XML and that software centers should just implement a lot of the actual logic. This has not been the case for a while, but there was still a lot of complex AppStream features that were hard for software centers to implement and where it makes sense to have one implementation that projects can just use.

The validation of component relations is one such thing. This was implemented in 0.16.x as well, but 1.0 vastly improves upon the compatibility checks, so you can now just run as_component_check_relations and retrieve a detailed list of whether the current component will run well on the system. Besides better API for software developers, the appstreamcli utility also has much improved support for relation checks, and I wrote about these changes in a previous post. Check it out!

With these changes, I hope this feature will be used much more, and beyond just drivers and firmware.

So much more!

The changelog for the 1.0 release is huge, and there are many papercuts resolved and changes made that I did not talk about here, like us using gi-docgen (instead of gtkdoc) now for nice API documentation, or the many improvements that went into better binding support, or better search, or just plain bugfixes.


I expect the transition to 1.0 to take a bit of time. AppStream has not broken its API for many, many years (since 2016), so a bunch of places need to be touched even if the changes themselves are minor in many cases. In hindsight, I should have also released 1.0 much sooner and it should not have become such a mega-release, but that was mainly due to time constraints.

So, what’s in it for the future? Contrary to what I thought, AppStream does not really seem to be “done” and fetature complete at a point, there is always something to improve, and people come up with new usecases all the time. So, expect more of the same in future: Bugfixes, validator improvements, documentation improvements, better tools and the occasional new feature.

Onwards to 1.0.1! �

11 November, 2023 07:48PM by Matthias

Reproducible Builds

Reproducible Builds in October 2023

Welcome to the October 2023 report from the Reproducible Builds project. In these reports we outline the most important things that we have been up to over the past month. As a quick recap, whilst anyone may inspect the source code of free software for malicious flaws, almost all software is distributed to end users as pre-compiled binaries.

Reproducible Builds Summit 2023

Between October 31st and November 2nd, we held our seventh Reproducible Builds Summit in Hamburg, Germany!

Our summits are a unique gathering that brings together attendees from diverse projects, united by a shared vision of advancing the Reproducible Builds effort, and this instance was no different.

During this enriching event, participants had the opportunity to engage in discussions, establish connections and exchange ideas to drive progress in this vital field. A number of concrete outcomes from the summit will documented in the report for November 2023 and elsewhere.

Amazingly the agenda and all notes from all sessions are already online.

The Reproducible Builds team would like to thank our event sponsors who include Mullvad VPN, openSUSE, Debian, Software Freedom Conservancy, Allotropia and Aspiration Tech.

Reflections on Reflections on Trusting Trust

Russ Cox posted a fascinating article on his blog prompted by the fortieth anniversary of Ken Thompson’s award-winning paper, Reflections on Trusting Trust:

[…] In March 2023, Ken gave the closing keynote [and] during the Q&A session, someone jokingly asked about the Turing award lecture, specifically “can you tell us right now whether you have a backdoor into every copy of gcc and Linux still today?”

Although Ken reveals (or at least claims!) that he has no such backdoor, he does admit that he has the actual code… which Russ requests and subsequently dissects in great but accessible detail.

Ecosystem factors of reproducible builds

Rahul Bajaj, Eduardo Fernandes, Bram Adams and Ahmed E. Hassan from the Maintenance, Construction and Intelligence of Software (MCIS) laboratory within the School of Computing, Queen’s University in Ontario, Canada have published a paper on the “Time to fix, causes and correlation with external ecosystem factors” of unreproducible builds.

The authors compare various response times within the Debian and Arch Linux distributions including, for example:

Arch Linux packages become reproducible a median of 30 days quicker when compared to Debian packages, while Debian packages remain reproducible for a median of 68 days longer once fixed.

A full PDF of their paper is available online, as are many other interesting papers on MCIS’ publication page.

NixOS installation image reproducible

On the NixOS Discourse instance, Arnout Engelen (raboof) announced that NixOS have created an independent, bit-for-bit identical rebuilding of the nixos-minimal image that is used to install NixOS. In their post, Arnout details what exactly can be reproduced, and even includes some of the history of this endeavour:

You may remember a 2021 announcement that the minimal ISO was 100% reproducible. While back then we successfully tested that all packages that were needed to build the ISO were individually reproducible, actually rebuilding the ISO still introduced differences. This was due to some remaining problems in the hydra cache and the way the ISO was created. By the time we fixed those, regressions had popped up (notably an upstream problem in Python 3.10), and it isn’t until this week that we were back to having everything reproducible and being able to validate the complete chain.

Congratulations to NixOS team for reaching this important milestone! Discussion about this announcement can be found underneath the post itself, as well as on Hacker News.

CPython source tarballs now reproducible

Seth Larson published a blog post investigating the reproducibility of the CPython source tarballs. Using diffoscope, reprotest and other tools, Seth documents his work that led to a pull request to make these files reproducible which was merged by Łukasz Langa.

New arm64 hardware from Codethink

Long-time sponsor of the project, Codethink, have generously replaced our old “Moonshot-Slides”, which they have generously hosted since 2016 with new KVM-based arm64 hardware. Holger Levsen integrated these new nodes to the Reproducible Builds’ continuous integration framework.

Community updates

On our mailing list during October 2023 there were a number of threads, including:

  • Vagrant Cascadian continued a thread about the implementation details of a “snapshot” archive server required for reproducing previous builds. []

  • Akihiro Suda shared an update on BuildKit, a toolkit for building Docker container images. Akihiro links to a interesting talk they recently gave at DockerCon titled Reproducible builds with BuildKit for software supply-chain security.

  • Alex Zakharov started a thread discussing and proposing fixes for various tools that create ext4 filesystem images. []

Elsewhere, Pol Dellaiera made a number of improvements to our website, including fixing typos and links [][], adding a NixOS “Flake” file [] and sorting our publications page by date [].

Vagrant Cascadian presented Reproducible Builds All The Way Down at the Open Source Firmware Conference.

Distribution work

distro-info is a Debian-oriented tool that can provide information about Debian (and Ubuntu) distributions such as their codenames (eg. bookworm) and so on. This month, Benjamin Drung uploaded a new version of distro-info that added support for the SOURCE_DATE_EPOCH environment variable in order to close bug #1034422. In addition, 8 reviews of packages were added, 74 were updated and 56 were removed this month, all adding to our knowledge about identified issues.

Bernhard M. Wiedemann published another monthly report about reproducibility within openSUSE.

Software development

The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

In addition, Chris Lamb fixed an issue in diffoscope, where if the equivalent of file -i returns text/plain, fallback to comparing as a text file. This was originally filed as Debian bug #1053668) by Niels Thykier. [] This was then uploaded to Debian (and elsewhere) as version 251.

Reproducibility testing framework

The Reproducible Builds project operates a comprehensive testing framework (available at tests.reproducible-builds.org) in order to check packages and other artifacts for reproducibility. In October, a number of changes were made by Holger Levsen:

  • Debian-related changes:

    • Refine the handling of package blacklisting, such as sending blacklisting notifications to the #debian-reproducible-changes IRC channel. [][][]
    • Install systemd-oomd on all Debian bookworm nodes (re. Debian bug #1052257). []
    • Detect more cases of failures to delete schroots. []
    • Document various bugs in bookworm which are (currently) being manually worked around. []
  • Node-related changes:

  • Monitoring-related changes:

    • Remove unused Munin monitoring plugins. []
    • Complain less visibly about “too many” installed kernels. []
  • Misc:

    • Enhance the firewall handling on Jenkins nodes. [][][][]
    • Install the fish shell everywhere. []

In addition, Vagrant Cascadian added some packages and configuration for snapshot experiments. []

If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

11 November, 2023 12:39PM

November 10, 2023

François Marier

Upgrading from Debian 11 bullseye to 12 bookworm

Over the last few months, I upgraded my Debian machines from bullseye to bookworm. The process was uneventful, but I ended up reconfiguring several things afterwards in order to modernize my upgraded machines.


I noticed in this release that the transition to journald is essentially complete. This means that rsyslog is no longer needed on most of my systems:

apt purge rsyslog

Once that was done, I was able to comment out the following lines in /etc/logcheck/logcheck.logfiles.d/syslog.logfiles:


I did have to adjust some of my custom logcheck rules, particularly the ones that deal with kernel messages:

--- a/logcheck/ignore.d.server/local-kernel
+++ b/logcheck/ignore.d.server/local-kernel
@@ -1,1 +1,1 @@
-^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ kernel: \[[0-9. ]+]\ IN=eno1 OUT= MAC=[0-9a-f:]+ SRC=[0-9a-f.:]+
+^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ kernel: (\[[0-9. ]+]\ )?IN=eno1 OUT= MAC=[0-9a-f:]+ SRC=[0-9a-f.:]+

Then I moved local entries from /etc/logcheck/logcheck.logfiles to /etc/logcheck/logcheck.logfiles.d/local.logfiles (/var/log/syslog and /var/log/auth.log are enabled by default when needed) and removed some files that are no longer used:

rm /var/log/mail.err*
rm /var/log/mail.warn*
rm /var/log/mail.info*

Finally, I had to fix any unescaped | characters in my local rules. For example error == NULL || \*error == NULL must now be written as error == NULL \|\| \*error == NULL.


After the upgrade, I got a notice that the isc-dhcp-client is now deprecated and so I removed if from my system:

apt purge isc-dhcp-client

This however meant that I need to ensure that my network configuration software does not depend on the now-deprecated DHCP client.

On my laptop, I was already using NetworkManager for my main network interfaces and that has built-in DHCP support.

Migration to systemd-networkd

On my backup server, I took this opportunity to switch from ifupdown to systemd-networkd by removing ifupdown:

apt purge ifupdown
rm /etc/network/interfaces

putting the following in /etc/systemd/network/20-wired.network:



and then enabling/starting systemd-networkd:

systemctl enable systemd-networkd
systemctl start systemd-networkd

I also needed to install polkit:

apt install --no-install-recommends policykit-1

in order to allow systemd-networkd to set the hostname.

In order to start my firewall automatically as interfaces are brought up, I wrote a dispatcher script to apply my existing iptables rules.

Migration to predictacle network interface names

On my Linode server, I did the same as on the backup server, but I put the following in /etc/systemd/network/20-wired.network since it has a static IPv6 allocation:



and switched to predictable network interface names by deleting these two files:

  • /etc/systemd/network/50-virtio-kernel-names.link
  • /etc/systemd/network/99-default.link

and then changing eth0 to enp0s4 in:

  • /etc/network/iptables.up.rules
  • /etc/network/ip6tables.up.rules
  • /etc/rc.local (for OpenVPN)
  • /etc/logcheck/ignored.d.*/*

Then I regenerated all initramfs:

update-initramfs -u -k all

and rebooted the virtual machine.

Giving systemd-resolved control of /etc/resolv.conf

After reading this history of DNS resolution on Linux, I decided to modernize my resolv.conf setup and let systemd-resolved handle /etc/resolv.conf.

I installed the package:

apt install systemd-resolved

and then removed no-longer-needed packages:

apt purge resolvconf avahi-daemon

I also disabled support for Link-Local Multicast Name Resolution (LLMNR) after reading this person's reasoning by putting the following in /etc/systemd/resolved.conf.d/llmnr.conf:


I verified that mDNS is enabled and LLMNR is disabled:

$ resolvectl mdns
Global: yes
Link 2 (enp0s25): yes
Link 3 (wlp3s0): yes
$ resolvectl llmnr
Global: no
Link 2 (enp0s25): no
Link 3 (wlp3s0): no

Note that if you want auto-discovery of local printers using CUPS, you need to keep avahi-daemon since cups-browsed doesn't support systemd-resolved. You can verify that it works using:

sudo lpinfo --include-schemes dnssd -v

Dynamic DNS

I replaced ddclient with inadyn since it doesn't work with no-ip.com anymore, using the configuration I described in an old blog post.


I moved my customizations in /etc/chkrootkit.conf to /etc/chkrootkit/chkrootkit.conf after seeing this message in my logs:

WARNING: /etc/chkrootkit.conf is deprecated. Please put your settings in /etc/chkrootkit/chkrootkit.conf instead: /etc/chkrootkit.conf will be ignored in a future release and should be deleted.


As mentioned in Debian bug#1018106, to silence the following warnings:

sshd[6283]: pam_env(sshd:session): deprecated reading of user environment enabled

I changed the following in /etc/pam.d/sshd:

--- a/pam.d/sshd
+++ b/pam.d/sshd
@@ -44,7 +44,7 @@ session    required     pam_limits.so
 session    required     pam_env.so # [1]
 # In Debian 4.0 (etch), locale-related environment variables were moved to
 # /etc/default/locale, so read that as well.
-session    required     pam_env.so user_readenv=1 envfile=/etc/default/locale
+session    required     pam_env.so envfile=/etc/default/locale

 # SELinux needs to intervene at login time to ensure that the process starts
 # in the proper default security context.  Only sessions which are intended

I also made the following changes to /etc/ssh/sshd_config.d/local.conf based on the advice of ssh-audit 2.9.0:

-KexAlgorithms curve25519-sha256@libssh.org,curve25519-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha256
+KexAlgorithms curve25519-sha256@libssh.org,curve25519-sha256,sntrup761x25519-sha512@openssh.com,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512

10 November, 2023 06:01AM

November 07, 2023

hackergotchi for Steinar H. Gunderson

Steinar H. Gunderson

systemd shower thought

Something I thought of recently: It would be pretty nice if you could somehow connect screen (or tmux) to systemd units, so that you could just connect to running daemons and interact with them as if you started them in the foreground. (Nothing for Apache, of course, but there are certainly programs you'd like systemd to manage but that have more fancy TUIs.)

07 November, 2023 08:56PM

hackergotchi for Matthew Palmer

Matthew Palmer

PostgreSQL Encryption: The Available Options

On an episode of Postgres FM, the hosts had a (very brief) discussion of data encryption in PostgreSQL. While Postgres FM is a podcast well worth a subscribe, the hosts aren’t data security experts, and so as someone who builds a queryable database encryption system, I found the coverage to be somewhat… lacking. I figured I’d provide a more complete survey of the available options for PostgreSQL-related data encryption.

The Status Quo

By default, when you install PostgreSQL, there is no data encryption at all. That means that anyone who gets access to any part of the system can read all the data they have access to.

This is, of course, not peculiar to PostgreSQL: basically everything works much the same way.

What’s stopping an attacker from nicking off with all your data is the fact that they can’t access the database at all. The things that are acting as protection are “perimeter” defences, like putting the physical equipment running the server in a secure datacenter, firewalls to prevent internet randos connecting to the database, and strong passwords.

This is referred to as “tortoise” security – it’s tough on the outside, but soft on the inside. Once that outer shell is cracked, the delicious, delicious data is ripe for the picking, and there’s absolutely nothing to stop a miscreant from going to town and making off with everything.

It’s a good idea to plan your defenses on the assumption you’re going to get breached sooner or later. Having good defence-in-depth includes denying the attacker to your data even if they compromise the database. This is where encryption comes in.

Storage-Layer Defences: Disk / Volume Encryption

To protect against the compromise of the storage that your database uses (physical disks, EBS volumes, and the like), it’s common to employ encryption-at-rest, such as full-disk encryption, or volume encryption. These mechanisms protect against “offline” attacks, but provide no protection while the system is actually running. And therein lies the rub: your database is always running, so encryption at rest typically doesn’t provide much value.

If you’re running physical systems, disk encryption is essential, but more to prevent accidental data loss, due to things like failing to wipe drives before disposing of them, rather than physical theft. In systems where volume encryption is only a tickbox away, it’s also worth enabling, if only to prevent inane questions from your security auditors. Relying solely on storage-layer defences, though, is very unlikely to provide any appreciable value in preventing data loss.

Database-Layer Defences: Transparent Database Encryption

If you’ve used proprietary database systems in high-security environments, you might have come across Transparent Database Encryption (TDE). There are also a couple of proprietary extensions for PostgreSQL that provide this functionality.

TDE is essentially encryption-at-rest implemented inside the database server. As such, it has much the same drawbacks as disk encryption: few real-world attacks are thwarted by it. There is a very small amount of additional protection, in that “physical” level backups (as produced by pg_basebackup) are protected, but the vast majority of attacks aren’t stopped by TDE. Any attacker who can access the database while it’s running can just ask for an SQL-level dump of the stored data, and they’ll get the unencrypted data quick as you like.

Application-Layer Defences: Field Encryption

If you want to take the database out of the threat landscape, you really need to encrypt sensitive data before it even gets near the database. This is the realm of field encryption, more commonly known as application-level encryption.

This technique involves encrypting each field of data before it is sent to be stored in the database, and then decrypting it again after it’s retrieved from the database. Anyone who gets the data from the database directly, whether via a backup or a direct connection, is out of luck: they can’t decrypt the data, and therefore it’s worthless.

There are, of course, some limitations of this technique.

For starters, every ORM and data mapper out there has rolled their own encryption format, meaning that there’s basically zero interoperability. This isn’t a problem if you build everything that accesses the database using a single framework, but if you ever feel the need to migrate, or use the database from multiple codebases, you’re likely in for a rough time.

The other big problem of traditional application-level encryption is that, when the database can’t understand what data its storing, it can’t run queries against that data. So if you want to encrypt, say, your users’ dates of birth, but you also need to be able to query on that field, you need to choose between one or the other: you can’t have both at the same time.

You may think to yourself, “but this isn’t any good, an attacker that breaks into my application can still steal all my data!”. That is true, but security is never binary. The name of the game is reducing the attack surface, making it harder for an attacker to succeed. If you leave all the data unencrypted in the database, an attacker can steal all your data by breaking into the database or by breaking into the application. Encrypting the data reduces the attacker’s options, and allows you to focus your resources on hardening the application against attack, safe in the knowledge that an attacker who gets into the database directly isn’t going to get anything valuable.

Sidenote: The Curious Case of pg_crypto

PostgreSQL ships a “contrib” module called pg_crypto, which provides encryption and decryption functions. This sounds ideal to use for encrypting data within our applications, as it’s available no matter what we’re using to write our application. It avoids the problem of framework-specific cryptography, because you call the same PostgreSQL functions no matter what language you’re using, which produces the same output.

However, I don’t recommend ever using pg_crypto’s data encryption functions, and I doubt you will find many other cryptographic engineers who will, either.

First up, and most horrifyingly, it requires you to pass the long-term keys to the database server. If there’s an attacker actively in the database server, they can capture the keys as they come in, which means all the data encrypted using that key is exposed. Sending the keys can also result in the keys ending up in query logs, both on the client and server, which is obviously a terrible result.

Less scary, but still very concerning, is that pg_crypto’s available cryptography is, to put it mildly, antiquated. We have a lot of newer, safer, and faster techniques for data encryption, that aren’t available in pg_crypto. This means that if you do use it, you’re leaving a lot on the table, and need to have skilled cryptographic engineers on hand to avoid the potential pitfalls.

In short: friends don’t let friends use pg_crypto.

The Future: Enquo

All this brings us to the project I run: Enquo. It takes application-layer encryption to a new level, by providing a language- and framework-agnostic cryptosystem that also enables encrypted data to be efficiently queried by the database.

So, you can encrypt your users’ dates of birth, in such a way that anyone with the appropriate keys can query the database to return, say, all users over the age of 18, but an attacker just sees unintelligible gibberish. This should greatly increase the amount of data that can be encrypted, and as the Enquo project expands its available data types and supported languages, the coverage of encrypted data will grow and grow. My eventual goal is to encrypt all data, all the time.

If this appeals to you, visit enquo.org to use or contribute to the open source project, or EnquoDB.com for commercial support and hosted database options.

07 November, 2023 12:00AM by Matt Palmer (mpalmer@hezmatt.org)

November 05, 2023

Vincent Bernat

Non-interactive SSH password authentication

SSH offers several forms of authentication, such as passwords and public keys. The latter are considered more secure. However, password authentication remains prevalent, particularly with network equipment.1

A classic solution to avoid typing a password for each connection is sshpass, or its more correct variant passh. Here is a wrapper for Zsh, getting the password from pass, a simple password manager:2

pssh() {
  passh -p <(pass show network/ssh/password | head -1) ssh "$@"
compdef pssh=ssh

This approach is a bit brittle as it requires to parse the output of the ssh command to look for a password prompt. Moreover, if no password is required, the password manager is still invoked. Since OpenSSH 8.4, we can use SSH_ASKPASS and SSH_ASKPASS_REQUIRE instead:

ssh() {
  set -o localoptions -o localtraps
  local passname=network/ssh/password
  local helper=$(mktemp)
  trap "command rm -f $helper" EXIT INT
  > $helper <<EOF
pass show $passname | head -1
  chmod u+x $helper
  SSH_ASKPASS=$helper SSH_ASKPASS_REQUIRE=force command ssh "$@"

If the password is incorrect, we can display a prompt on the second tentative:

ssh() {
  set -o localoptions -o localtraps
  local passname=network/ssh/password
  local helper=$(mktemp)
  trap "command rm -f $helper" EXIT INT
  > $helper <<EOF
if [ -k $helper ]; then
    oldtty=\$(stty -g)
    trap 'stty \$oldtty < /dev/tty 2> /dev/null' EXIT INT TERM HUP
    stty -echo
    print "\rpassword: "
    read password
    printf "\n"
  } > /dev/tty < /dev/tty
  printf "%s" "\$password"
  pass show $passname | head -1
  chmod +t $helper
  chmod u+x $helper
  SSH_ASKPASS=$helper SSH_ASKPASS_REQUIRE=force command ssh "$@"

A possible improvement is to use a different password entry depending on the remote host:3

ssh() {
  # Grab login information
  local -A details
  details=(${=${(M)${:-"${(@f)$(command ssh -G "$@" 2>/dev/null)}"}:#(host|hostname|user) *}})
  local remote=${details[host]:-details[hostname]}
  local login=${details[user]}@${remote}

  # Get password name
  local passname
  case "$login" in
    admin@*.example.net)  passname=company1/ssh/admin ;;
    bernat@*.example.net) passname=company1/ssh/bernat ;;
    backup@*.example.net) passname=company1/ssh/backup ;;

  # No password name? Just use regular SSH
  [[ -z $passname ]] && {
    command ssh "$@"
    return $?

  # Invoke SSH with the helper for SSH_ASKPASS
  # […]

It is also possible to make scp invoke our custom ssh function:

scp() {
  set -o localoptions -o localtraps
  local helper=$(mktemp)
  trap "command rm -f $helper" EXIT INT
  > $helper <<EOF 
source ${(%):-%x}
ssh "\$@"
  command scp -S $helper "$@"

For the complete code, have a look at my zshrc. As an alternative, you can put the ssh() function body into its own script file and replace command ssh with /usr/bin/ssh to avoid an unwanted recursive call. In this case, the scp() function is not needed anymore.

  1. First, some vendors make it difficult to associate an SSH key with a user. Then, many vendors do not support certificate-based authentication, making it difficult to scale. Finally, interactions between public-key authentication and finer-grained authorization methods like TACACS+ and Radius are still uncharted territory. ↩︎

  2. The clear-text password never appears on the command line, in the environment, or on the disk, making it difficult for a third party without elevated privileges to capture it. On Linux, Zsh provides the password through a file descriptor. ↩︎

  3. To decipher the fourth line, you may get help from print -l and the zshexpn(1) manual page. details is an associative array defined from an array alternating keys and values. ↩︎

05 November, 2023 05:25PM by Vincent Bernat

Thorsten Alteholz

My Debian Activities in October 2023

FTP master

This month I accepted 361 and rejected 34 packages. The overall number of packages that got accepted was 362.

Debian LTS

This was my hundred-twelfth month that I did some work for the Debian LTS initiative, started by Raphael Hertzog at Freexian.

During my allocated time I uploaded:

  • [DLA 3615-1] libcue security update for one CVE to fix an out-of-bounds array access
  • [DLA 3631-1] xorg-server security update for two CVEs. These were embargoed issues related to privilege escalation
  • [DLA 3633-1] gst-plugins-bad1.0 security update for three CVEs to fix possible DoS or arbitrary code execution when processing crafted media files.
  • [1052361]bookworm-pu: the upload has been done and processed for the point release
  • [1052363]bullseye-pu: the upload has been done and processed for the point release

Unfortunately upstream still could not resolve whether the patch for CVE-2023-42118 of libspf2 is valid, so no progress happened here.
I also continued to work on bind9 and try to understand why some tests fail.

Last but not least I did some days of frontdesk duties and took part in the LTS meeting.

Debian ELTS

This month was the sixty-third ELTS month. During my allocated time I uploaded:

  • [ELA-978-1]cups update in Jessie and Stretch for two CVEs. One issue is related to missing boundary checks which might lead to code execution when using crafted postscript documents. The other issue is related to unauthorized access to recently printed documents.
  • [ELA-990-1]xorg-server update in Jessie and Stretch for two CVEs. These were embargoed issues related to privilege escalation.
  • [ELA-993-1]gst-plugins-bad1.0 update in Jessie and Stretch for three CVEs to fix possible DoS or arbitrary code execution when processing crafted media files.

I also continued to work on bind9 and as with the version in LTS, I try to understand why some tests fail.

Last but not least I did some days of frontdesk duties .

Debian Printing

This month I uploaded a new upstream version of:

Within the context of preserving old printing packages, I adopted:

If you know of any other package that is also needed and still maintained by the QA team, please tell me.

I also uploaded new upstream version of packages or uploaded a package to fix one or the other issue:

This work is generously funded by Freexian!

Debian Mobcom

This month I uploaded a package to fix one or the other issue:

  • osmo-pcu The bug was filed by Helmut and was related to /usr-merge

Other stuff

This month I uploaded new upstream version of packages, did a source upload for the transition or uploaded it to fix one or the other issue:

05 November, 2023 05:01PM by alteholz

Iustin Pop

Corydalis: new release and switching to date-versioning

After 4 years, I finally managed to tag a new release of Corydalis. There’s nothing special about this specific point in time, but there was also none in the last four years, so I gave up on trying to any kind of usual version release, and simply switched to CalVer.

So, Corydalis 2023.44.0 is up and running on https://demo.corydalis.io. I am 100% sure I’m the only one using it, but doing it open-source is nicer, and I still can’t imagine another way of managing/browsing my photo library (that keeps it under my own control), so I keep doing 10-20 commits per year to it.

There’s a lot of bugs to fix and functionality to improve (main thing - a real video player), but until I can find a chunk of free time, it is what it is 😣.

05 November, 2023 01:21PM

November 04, 2023

hackergotchi for Dirk Eddelbuettel

Dirk Eddelbuettel

RcppEigen on CRAN: Maintenance, Matrix Changes

A new release of RcppEigen arrived on CRAN yesterday, and went to Debian today. Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.

This update contains a small amount of the usual maintenance (see below), along with a very nice pull request by Mikael Jagan which simplifies to interface with the Matrix package and inparticular the CHOLMOD library that is part of SuiteSparse. This release is coordinated with lme4 and OpenMx which are also being updated.

The complete NEWS file entry follows.

Changes in RcppEigen version (2023-11-01)

  • The CITATION file has been updated for the new bibentry style.

  • The package skeleton generator has been updated and no longer sets an Imports:.

  • Some README.md URLs and badged have been updated.

  • The use of -fopenmp has been documented in Makevars, and a simple thread-count reporting function has been added.

  • The old manual src/init.c has been replaced by an autogenerated version, the RcppExports file have regenerated

  • The interface to package Matrix has been updated and simplified thanks to an excllent patch by Mikael Jagan.

  • The new upload is coordinated with packages lme4 and OpenMx.

Courtesy of CRANberries, there is also a diffstat report for the most recent release.

If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

04 November, 2023 02:37AM

November 02, 2023

hackergotchi for Joey Hess

Joey Hess

become ungoogleable

I've removed my website from indexing by Google. The proximate cause is Google's new effort to DRM the web (archive) but there is of course so much more.

This is a unique time, when it's actually feasible to become ungoogleable without losing much. Nobody really expects to be able to find anything of value in a Google search now, so if they're looking for me or something I've made and don't find it, they'll use some other approach.

I've looked over the kind of traffic that Google refers to my website, and it will not be a significant loss even if those people fail to find me by some other means. Over 30% of the traffic to this website is rss feeds. Google just doesn't matter on the modern web.

The web will end one day. But let's not let Google kill it.

02 November, 2023 10:41PM

Reproducible Builds

Farewell from the Reproducible Builds Summit 2023!

Farewell from the Reproducible Builds summit, which just took place in Hamburg, Germany:

This year, we were thrilled to host the seventh edition of this exciting event. Topics covered this year included:

  • Project updates from openSUSE, Fedora, Debian, ElectroBSD, Reproducible Central and NixOS
  • Mapping the “big picture”
  • Towards a snapshot service
  • Understanding user-facing needs and personas
  • Language-specific package managers
  • Defining our definitions
  • Creating a “Ten Commandments” of reproducibility
  • Embedded systems
  • Next steps in GNU Guix’ reproducibility
  • Signature storage and sharing
  • Public verification services
  • Verification use cases
  • Web site audiences
  • Enabling new projects to be “born reproducible”
  • Collecting reproducibility success stories
  • Reproducibility’s relationship to SBOMs
  • SBOMs for RPM-based distributions
  • Filtering diffoscope output
  • Reproducibility of filesystem images, filesystems and containers
  • Using verification data
  • A deep-dive on Fedora and Arch Linux package reproducibility
  • Debian rebuild archive service discussion

… as well as countless informal discussions and hacking sessions into the night. Projects represented at the venue included:

Debian, openSUSE, QubesOS, GNU Guix, Arch Linux, phosh, Mobian, PureOS, JustBuild, LibreOffice, Warpforge, OpenWrt, F-Droid, NixOS, ElectroBSD, Apache Security, Buildroot, Systemd, Apache Maven, Fedora, Privoxy, CHAINS (KTH Royal Institute of Technology), coreboot, GitHub, Tor Project, Ubuntu, rebuilderd, repro-env, spytrap-adb, arch-repro-status, etc.

A huge thanks to our sponsors and partners for making the event possible:


Event facilitation


Platinum sponsor

If you weren’t able to make it this year, don’t worry; just look out for an announcement in 2024 for the next event.

02 November, 2023 12:00AM

November 01, 2023

hackergotchi for Joachim Breitner

Joachim Breitner

Joining the Lean FRO

Tomorrow is going to be a new first day in a new job for me: I am joining the Lean FRO, and I’m excited.

What is Lean?

Lean is the new kid on the block of theorem provers.

It’s a pure functional programming language (like Haskell, with and on which I have worked a lot), but it’s dependently typed (which Haskell may be evolving to be as well, but rather slowly and carefully). It has a refreshing syntax, built on top of a rather good (I have been told, not an expert here) macro system.

As a dependently typed programming language, it is also a theorem prover, or proof assistant, and there exists already a lively community of mathematicians who started to formalize mathematics in a coherent library, creatively called mathlib.

What is a FRO?

A Focused Research Organization has the organizational form of a small start up (small team, little overhead, a few years of runway), but its goals and measure for success are not commercial, as funding is provided by donors (in the case of the Lean FRO, the Simons Foundation International, the Alfred P. Sloan Foundation, and Richard Merkin). This allows us to build something that we believe is a contribution for the greater good, even though it’s not (or not yet) commercially interesting enough and does not fit other forms of funding (such as research grants) well. This is a very comfortable situation to be in.

Why am I excited?

To me, working on Lean seems to be the perfect mix: I have been working on language implementation for about a decade now, and always with a preference for functional languages. Add to that my interest in theorem proving, where I have used Isabelle and Coq so far, and played with Agda and others. So technically, clearly up my alley.

Furthermore, the language isn’t too old, and plenty of interesting things are simply still to do, rather than tried before. The ecosystem is still evolving, so there is a good chance to have some impact.

On the other hand, the language isn’t too young either. It is no longer an open question whether we will have users: we have them already, they hang out on zulip, so if I improve something, there is likely someone going to be happy about it, which is great. And the community seems to be welcoming and full of nice people.

Finally, this library of mathematics that these users are building is itself an amazing artifact: Lots of math in a consistent, machine-readable, maintained, documented, checked form! With a little bit of optimism I can imagine this changing how math research and education will be done in the future. It could be for math what Wikipedia is for encyclopedic knowledge and OpenStreetMap for maps – and the thought of facilitating that excites me.

With this new job I find that when I am telling friends and colleagues about it, I do not hesitate or hedge when asked why I am doing this. This is a good sign.

What will I be doing?

We’ll see what main tasks I’ll get to tackle initially, but knowing myself, I expect I’ll get broadly involved.

To get up to speed I started playing around with a few things already, and for example created Loogle, a Mathlib search engine inspired by Haskell’s Hoogle, including a Zulip bot integration. This seems to be useful and quite well received, so I’ll continue maintaining that.

Expect more about this and other contributions here in the future.

01 November, 2023 08:47PM by Joachim Breitner (mail@joachim-breitner.de)

hackergotchi for Matthew Garrett

Matthew Garrett


"Why does ACPI exist" - - the greatest thread in the history of forums, locked by a moderator after 12,239 pages of heated debate, wait no let me start again.

Why does ACPI exist? In the beforetimes power management on x86 was done by jumping to an opaque BIOS entry point and hoping it would do the right thing. It frequently didn't. We called this Advanced Power Management (Advanced because before this power management involved custom drivers for every machine and everyone agreed that this was a bad idea), and it involved the firmware having to save and restore the state of every piece of hardware in the system. This meant that assumptions about hardware configuration were baked into the firmware - failed to program your graphics card exactly the way the BIOS expected? Hurrah! It's only saved and restored a subset of the state that you configured and now potential data corruption for you. The developers of ACPI made the reasonable decision that, well, maybe since the OS was the one setting state in the first place, the OS should restore it.

So far so good. But some state is fundamentally device specific, at a level that the OS generally ignores. How should this state be managed? One way to do that would be to have the OS know about the device specific details. Unfortunately that means you can't ship the computer without having OS support for it, which means having OS support for every device (exactly what we'd got away from with APM). This, uh, was not an option the PC industry seriously considered. The alternative is that you ship something that abstracts the details of the specific hardware and makes that abstraction available to the OS. This is what ACPI does, and it's also what things like Device Tree do. Both provide static information about how the platform is configured, which can then be consumed by the OS and avoid needing device-specific drivers or configuration to be built-in.

The main distinction between Device Tree and ACPI is that Device Tree is purely a description of the hardware that exists, and so still requires the OS to know what's possible - if you add a new type of power controller, for instance, you need to add a driver for that to the OS before you can express that via Device Tree. ACPI decided to include an interpreted language to allow vendors to expose functionality to the OS without the OS needing to know about the underlying hardware. So, for instance, ACPI allows you to associate a device with a function to power down that device. That function may, when executed, trigger a bunch of register accesses to a piece of hardware otherwise not exposed to the OS, and that hardware may then cut the power rail to the device to power it down entirely. And that can be done without the OS having to know anything about the control hardware.

How is this better than just calling into the firmware to do it? Because the fact that ACPI declares that it's going to access these registers means the OS can figure out that it shouldn't, because it might otherwise collide with what the firmware is doing. With APM we had no visibility into that - if the OS tried to touch the hardware at the same time APM did, boom, almost impossible to debug failures (This is why various hardware monitoring drivers refuse to load by default on Linux - the firmware declares that it's going to touch those registers itself, so Linux decides not to in order to avoid race conditions and potential hardware damage. In many cases the firmware offers a collaborative interface to obtain the same data, and a driver can be written to get that. this bug comment discusses this for a specific board)

Unfortunately ACPI doesn't entirely remove opaque firmware from the equation - ACPI methods can still trigger System Management Mode, which is basically a fancy way to say "Your computer stops running your OS, does something else for a while, and you have no idea what". This has all the same issues that APM did, in that if the hardware isn't in exactly the state the firmware expects, bad things can happen. While historically there were a bunch of ACPI-related issues because the spec didn't define every single possible scenario and also there was no conformance suite (eg, should the interpreter be multi-threaded? Not defined by spec, but influences whether a specific implementation will work or not!), these days overall compatibility is pretty solid and the vast majority of systems work just fine - but we do still have some issues that are largely associated with System Management Mode.

One example is a recent Lenovo one, where the firmware appears to try to poke the NVME drive on resume. There's some indication that this is intended to deal with transparently unlocking self-encrypting drives on resume, but it seems to do so without taking IOMMU configuration into account and so things explode. It's kind of understandable why a vendor would implement something like this, but it's also kind of understandable that doing so without OS cooperation may end badly.

This isn't something that ACPI enabled - in the absence of ACPI firmware vendors would just be doing this unilaterally with even less OS involvement and we'd probably have even more of these issues. Ideally we'd "simply" have hardware that didn't support transitioning back to opaque code, but we don't (ARM has basically the same issue with TrustZone). In the absence of the ideal world, by and large ACPI has been a net improvement in Linux compatibility on x86 systems. It certainly didn't remove the "Everything is Windows" mentality that many vendors have, but it meant we largely only needed to ensure that Linux behaved the same way as Windows in a finite number of ways (ie, the behaviour of the ACPI interpreter) rather than in every single hardware driver, and so the chances that a new machine will work out of the box are much greater than they were in the pre-ACPI period.

There's an alternative universe where we decided to teach the kernel about every piece of hardware it should run on. Fortunately (or, well, unfortunately) we've seen that in the ARM world. Most device-specific simply never reaches mainline, and most users are stuck running ancient kernels as a result. Imagine every x86 device vendor shipping their own kernel optimised for their hardware, and now imagine how well that works out given the quality of their firmware. Does that really seem better to you?

It's understandable why ACPI has a poor reputation. But it's also hard to figure out what would work better in the real world. We could have built something similar on top of Open Firmware instead but the distinction wouldn't be terribly meaningful - we'd just have Forth instead of the ACPI bytecode language. Longing for a non-ACPI world without presenting something that's better and actually stands a reasonable chance of adoption doesn't make the world a better place.

comment count unavailable comments

01 November, 2023 06:30AM

Paul Wise

FLOSS Activities October 2023


This month I didn't have any particular focus. I just worked on issues in my info bubble.




  • Debian wiki: RecentChanges for the month
  • Debian BTS usertags: changes for the month
  • Debian screenshots:


  • Debian IRC: rescue obsolete/unused #debian-wiki channel
  • Debian servers: rescue data from an old DebConf server
  • Debian wiki: approve accounts


  • Respond to queries from Debian users and contributors on the mailing lists and IRC


The SWH, golang-ginkgo, DBD-ODBC, sqliteodbc work was sponsored. All other work was done on a volunteer basis.

01 November, 2023 05:57AM

hackergotchi for Junichi Uekawa

Junichi Uekawa

Already November.

Already November. Been playing a bit with ureadahead. Build systems are hard. Resurrecting libnih to build again was a pain. Some tests rely on not being root so simply running things in Docker made it fail.

01 November, 2023 05:07AM by Junichi Uekawa

hackergotchi for Dirk Eddelbuettel

Dirk Eddelbuettel

RcppArmadillo on CRAN: Bugfix, Thread Throttling

armadillo image

Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language–and is widely used by (currently) 1110 other packages on CRAN, downloaded 31.2 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 563 times according to Google Scholar.

This release brings upstream bugfix releases 12.6.5 (sparse matrix corner case) and 12.6.6 with an ARPACK correction. Conrad released it this this morning, I had been running reverse dependency checks anyway and knew we were in good shape so for once I did not await a full run against the now over 1100 (!!) packages using RcppArmadillo.

This release also contains a change I prepared on Sunday and which helps with much-criticized (and rightly I may add) insistence by CRAN concerning ‘throttling’. The motivation is understandable: CRAN tests many packages at once on beefy servers and can ill afford tests going off and requesting numerous cores. But rather than providing a global setting at their end, CRAN insists that each package (!!) deals with this. The recent traffic on the helpful-as-ever r-pkg-devel mailing clearly shows that this confuses quite a few package developers. Some have admitted to simply turning examples and tests off: a net loss for all of us. Now, Armadillo defaults to using up to eight cores (which is enough to upset CRAN) when running with OpenMP (which is generally only on Linux for “reasons” I rather not get into…). With this release I expose a helper functions (from OpenMP) to limit this. I also set up an example package and repo RcppArmadilloOpenMPEx detailing this, and added a demonstration of how to use the new throttlers to the fastLm example. I hope this proves useful to users of the package.

The set of changes since the last CRAN release follows.

Changes in RcppArmadillo version (2023-10-31)

  • Upgraded to Armadillo release 12.6.6 (Cortisol Retox)

    • Fix eigs_sym(), eigs_gen() and svds() to generate deterministic results in ARPACK mode
  • Add helper functions to set and get the number of OpenMP threads

  • Store initial thread count at package load and use in thread-throttling helper (and resetter) suitable for CRAN constraints

Changes in RcppArmadillo version (2023-10-14)

  • Upgraded to Armadillo release 12.6.5 (Cortisol Retox)

    • Fix for corner-case bug in handling sparse matrices with no non-zero elements

Courtesy of my CRANberries, there is a diffstat report relative to previous release. More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the Rcpp R-Forge page.

If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

01 November, 2023 02:51AM

October 31, 2023

Iustin Pop

Raspberry PI OS: upgrading and cross-grading

One of the downsides of running Raspberry PI OS is the fact that - not having the resources of pure Debian - upgrades are not recommended, and cross-grades (migrating between armhf and arm64) is not even mentioned. Is this really true? It is, after all a Debian-based system, so it should in theory be doable. Let’s try!


The recently announced release based on Debian Bookworm here says:

We have always said that for a major version upgrade, you should re-image your SD card and start again with a clean image. In the past, we have suggested procedures for updating an existing image to the new version, but always with the caveat that we do not recommend it, and you do this at your own risk.

This time, because the changes to the underlying architecture are so significant, we are not suggesting any procedure for upgrading a Bullseye image to Bookworm; any attempt to do this will almost certainly end up with a non-booting desktop and data loss. The only way to get Bookworm is either to create an SD card using Raspberry Pi Imager, or to download and flash a Bookworm image from here with your tool of choice.

Which means, it’s time to actually try it 😊 … turns out it’s actually trivial, if you use RPIs as headless servers. I had only three issues:

  • if using an initrd, the new initrd-building scripts/hooks are looking for some binaries in /usr/bin, and not in /bin; solution: install manually the usrmerge package, and then re-run dpkg --configure -a;
  • also if using an initrd, the scripts are looking for the kernel config file in /boot/config-$(uname -r), and the raspberry pi kernel package doesn’t provide this; workaround: modprobe configs && zcat /proc/config.gz > /boot/config-$(uname -r);
  • and finally, on normal RPI systems, that don’t use manual configurations of interfaces in /etc/network/interface, migrating from the previous dhcpcd to NetworkManager will break network connectivity, and require you to log in locally and fix things.

I expect most people to hit only the 3rd, and almost no-one to use initrd on raspberry pi. But, overall, aside from these two issues and a couple of cosmetic ones (login.defs being rewritten from scratch and showing a baffling diff, for example), it was easy.

Is it worth doing? Definitely. Had no data loss, and no non-booting system.

Cross-grading (32 bit to 64 bit userland)

This one is actually painful. Internet searches go from “it’s possible, I think� to “it’s definitely not worth trying�. Examples:

Aside from these, there are a gazillion other posts about switching the kernel to 64 bit. And that’s worth doing on its own, but it’s only half the way.

So, armed with two different systems - a RPI4 4GB and a RPI Zero W2 - I tried to do this. And while it can be done, it takes many hours - first system was about 6 hours, second the same, and a third RPI4 probably took ~3 hours only since I knew the problematic issues.

So, what are the steps? Basically:

  • install devscripts, since you will need dget‼
  • enable new architecture in dpkg: dpkg --add-architecture arm64
  • switch over apt sources to include the 64 bit repos, which are different than the 32 bit ones (Raspberry PI OS did a migration here; normally a single repository has all architectures, of course)
  • downgrade all custom rpi packages/libraries to the standard bookworm/bullseye version, since dpkg won’t usually allow a single library package to have different versions (I think it’s possible to override, but I didn’t bother)
  • install libc for the arm64 arch (this takes some effort, it’s actually a set of 3-4 packages)
  • once the above is done, install whiptail:amd64 and rejoice at running a 64-bit binary!
  • then painfully go through sets of packages and migrate the “setâ€� to arm64:
    • sometimes this work via apt, sometimes you’ll need to use dget and dpkg -i
    • make sure you download both the armhf and arm64 versions before doing dpkg -i, since you’ll need to rollback some installs
  • at one point, you’ll be able to switch over dpkg and apt to arm64, at which point the default architecture flips over; from here, if you’ve done it at the right moment, it becomes very easy; you’ll probably need an apt install --fix-broken, though, at first
  • and then, finish by replacing all packages with arm64 versions
  • and then, dpkg --remove-architecture armhf, reboot, and profit!

But it’s tears and blood to get to that point �

Pain point 1: RPI custom versions of packages

Since the 32bit armhf architecture is a bit weird - having many variations - it turns out that raspberry pi OS has many packages that are very slightly tweaked to disable a compilation flag or work around build/test failures, or whatnot. Since we talk here about 64-bit capable processors, almost none of these are needed, but they do make life harder since the 64 bit version doesn’t have those overrides.

So what is needed would be to say “downgrade all armhf packages to the version in debian upstream repo�, but I couldn’t find the right apt pinning incantation to do that. So what I did was to remove the 32bit repos, then use apt-show-versions to see which packages have versions that are no longer in any repo, then downgrade them.

There’s a further, minor, complication that there were about 3-4 packages with same version but different hash (!), which simply needed apt install --reinstall, I think.

Pain point 2: architecture independent packages

There is one very big issue with dpkg in all this story, and the one that makes things very problematic: while you can have a library package installed multiple times for different architectures, as the files live in different paths, a non-library package can only be installed once (usually). For binary packages (arch:any), that is fine. But architecture-independent packages (arch:all) are problematic since usually they depend on a binary package, but they always depend on the default architecture version!

Hrmm, and I just realise I don’t have logs from this, so I’m only ~80% confident. But basically:

  • vim-solarized (arch:all) depends on vim (arch:any)
  • if you replace vim armhf with vim arm64, this will break vim-solarized, until the default architecture becomes arm64

So you need to keep track of which packages apt will de-install, for later re-installation.

It is possible that Multi-Arch: foreign solves this, per the debian wiki which says:

Note that even though Architecture: all and Multi-Arch: foreign may look like similar concepts, they are not. The former means that the same binary package can be installed on different architectures. Yet, after installation such packages are treated as if they were “native� architecture (by definition the architecture of the dpkg package) packages. Thus Architecture: all packages cannot satisfy dependencies from other architectures without being marked Multi-Arch foreign.

It also has warnings about how to properly use this. But, in general, not many packages have it, so it is a problem.

Pain point 3: remove + install vs overwrite

It seems that depending on how the solver computes a solution, when migrating a package from 32 to 64 bit, it can choose either to:

  • “overwrite in placeâ€� the package (akin to dpkg -i)
  • remove + install later

The former is OK, the later is not. Or, actually, it might be that apt never can do this, for example (edited for brevity):

# apt install systemd:arm64 --no-install-recommends
The following packages will be REMOVED:
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 1 to remove and 35 not upgraded.
Do you want to continue? [Y/n] y
dpkg: systemd: dependency problems, but removing anyway as you requested:
 systemd-sysv depends on systemd.

Removing systemd (247.3-7+deb11u2) ...
systemd is the active init system, please switch to another before removing systemd.
dpkg: error processing package systemd (--remove):
 installed systemd package pre-removal script subprocess returned error exit status 1
dpkg: too many errors, stopping
Errors were encountered while processing:
Processing was halted because there were too many errors.

But at the same time, overwrite in place is all good - via dpkg -i from /var/cache/apt/archives.

In this case it manifested via a prerm script, in other cases is manifests via dependencies that are no longer satisfied for packages that can’t be removed, etc. etc. So you will have to resort to dpkg -i a lot.

Pain point 4: lib- packages that are not lib

During the whole process, it is very tempting to just go ahead and install the corresponding arm64 package for all armhf lib… package, in one go, since these can coexist.

Well, this simple plan is complicated by the fact that some packages are named libfoo-bar, but are actual holding (e.g.) the bar binary for the libfoo package. Examples:

  • libmagic-mgc contains /usr/lib/file/magic.mgc, which conflicts between the 32 and 64 bit versions; of course, it’s the exact same file, so this should be an arch:all package, but…
  • libpam-modules-bin and liblockfile-bin actually contain binaries (per the -bin suffix)

It’s possible to work around all this, but it changes a 1 minute:

# apt install $(dpkg -i | grep ^ii | awk '{print $2}'|grep :amrhf|sed -e 's/:armhf/:arm64')

into a 10-20 minutes fight with packages (like most other steps).

Is it worth doing?

Compared to the simple bullseye → bookworm upgrade, I’m not sure about this. The result? Yes, definitely, the system feels - weirdly - much more responsive, logged in over SSH. I guess the arm64 base architecture has some more efficient ops than the “lowest denominator armhf�, so to say (e.g. there was in the 32 bit version some rpi-custom package with string ops), and thus migrating to 64 bit makes more things “faster�, but this is subjective so it might be actually not true.

But from the point of view of the effort? Unless you like to play with dpkg and apt, and understand how these work and break, I’d rather say, migrate to ansible and automate the deployment. It’s doable, sure, and by the third system, I got this nailed down pretty well, but it was a lot of time spent.

The good aspect is that I did 3 migrations:

  • rpi zero w2: bullseye 32 bit to 64 bit, then bullseye to bookworm
  • rpi 4: bullseye to bookworm, then bookworm 32bit to 64 bit
  • same, again, for a more important system

And all three worked well and no data loss. But I’m really glad I have this behind me, I probably wouldn’t do a fourth system, even if forced 😅

And now, waiting for the RPI 5 to be available… See you!

31 October, 2023 08:20PM

Russell Coker

hackergotchi for Bits from Debian

Bits from Debian

Call for bids for DebConf24

Due to the current state of affairs in Israel, who were to host DebConf24, the DebConf committee has decided to renew calls for bids to host DebConf24 at another venue and location.

The DebConf committee would like to express our sincere appreciation for the DebConf Israeli team, and the work they've done over several years. However, given the uncertainty about the situation, we regret that it will most likely not be possible to hold DebConf in Israel.

As we ask for submissions for new host locations we ask that you please review and understand the details and requirements for a bid submission to host the Debian Developer Conference.

Please review the template for a DebConf bid for guidelines on how to sumbit a proper bid.

To submit a bid, please create the appropriate page(s) under DebConf Wiki Bids, and add it to the "Bids" section in the main DebConf 24 page.

There isn't very much time to make a decision. We need bids by the end of November in order to make a decision by the end of the year.

After your submission is completed please send us a notification at debconf-team@lists.debian.org to let us know that your bid submission is ready for review.

We also suggest hanging out in our IRC chat room #debconf-team.

Given this short deadline, we understand that bids won't be as complete as they would usually be. Do the best you can in the time available.

Bids will be evaluated according to The Priority List.

You can get in contact with the DebConf team by email to debconf-team@lists.debian.org, or via the #debconf-team IRC channel on OFTC or via our Matrix Channel.

Thank you,

The Debian Debconf Committee

31 October, 2023 12:30PM by Debian DebConf Committe

October 29, 2023

hackergotchi for Joachim Breitner

Joachim Breitner

Squash your Github PRs with one click

TL;DR: Squash your PRs with one click at https://squasher.nomeata.de/.

Very recently I got this response from the project maintainer at a pull request I contributed: “Thanks, approved, please squash so that I can merge.”

It’s nice that my contribution can go it, but why did the maintainer not just press the “Squash and merge button”, and instead adds the this unnecessary roundtrip to the process? Anyways, maintainers make the rules, so I play by them. But unlike the maintainer, who can squash-and-merge with just one click, squashing the PR’s branch is surprisingly laberous: Github does not allow you to do that via the Web UI (and hence on mobile), and it seems you are expected to go to your computer and juggle with git rebase --interactive.

I found this rather annoying, so I created Squasher, a simple service that will squash your branch for you. There is no configuration, just paste the PR url. It will use the PR title and body as the commit message (which is obviously the right way™), and create the commit in your name:

Squasher in action
Squasher in action

If you find this useful, or found it to be buggy, let me know. The code is at https://github.com/nomeata/squasher if you are curious about it.

29 October, 2023 09:46PM by Joachim Breitner (mail@joachim-breitner.de)

Russell Coker

Hello Kitty

I’ve just discovered a new xterm replacement named Kitty [1]. It boasts about being faster due to threading and using the GPU and it does appear faster on some of my systems but that’s not why I like it.

A trend in terminal programs in recent years has been tabbed operation so you can have multiple sessions in one OS window, this is something I’ve never liked just as I’ve never liked using Screen to switch between sessions when I had the option of just having multiple sessions on screen. The feature that I like most about Kitty is the ability to have a grid based layout of sessions in one OS window. Instead of having 16 OS windows on my workstation or 4 OS windows on a laptop with different entries in the window list and the possibility of them getting messed up if the OS momentarily gets confused about the screen size (a common issue with laptop use) I can just have 1 Kitty window that has all the sessions running.

Kitty has “Kitten” processes that can do various things, one is icat which displays an image file to the terminal and leaves it in the scroll-back buffer. I put the following shell code in one of the scripts called from .bashrc to setup an alias for icat.

if [ "$TERM" == "xterm-kitty" ]; then
  alias icat='kitty +kitten icat'

The kitten interface can be supported by other programs. The version of the mpv video player in Debian/Unstable has a --vo=kitty option which is an interesting feature. However playing a video in a Kitty window that takes up 1/4 of the screen on my laptop takes a bit over 100% of a CPU core for mpv and about 10% to 20% for Kitty which gives a total of about 120% CPU use on my i5-6300U compared to about 20% for mpv using wayland directly. The option to make it talk to Kitty via shared memory doesn’t improve things.

Using this effectively requires installing the kitty-terminfo package on every system you might ssh to. But you can set the term type to xterm-256color when logged in to a system without the kitty terminfo installed. The fact that icat and presumably other advanced terminal functions work over ssh by default is a security concern, but this also works with Konsole and will presumably be added to other terminal emulators so it’s a widespread problem that needs attention.

There is support for desktop notifications in the Kitty terminal encoding [2]. One of the things I’m interested in at the moment is how to best manage notifications on converged systems (phone and desktop) so this is something I’ll have to investigate.

Overall Kitty has some great features and definitely has the potential to improve productivity for some work patterns. There are some security concerns that it raises through closer integration between systems and between programs, but many of them aren’t exclusive to Kitty.

29 October, 2023 12:26PM by etbe

October 28, 2023

François Marier

Remote logging of Turris Omnia log messages using syslog-ng and rsyslog

As part of debugging an upstream connection problem I've been seeing recently, I wanted to be able to monitor the logs from my Turris Omnia router. Here's how I configured it to send its logs to a server I already had on the local network.

Server setup

The first thing I did was to open up my server's rsyslog (Debian's default syslog server) to remote connections since it's going to be the destination host for the router's log messages.

I added the following to /etc/rsyslog.d/router.conf:

input(type="imtcp" port="514")

if $fromhost-ip == '' then {
    if $syslogseverity <= 5 then {
        action(type="omfile" file="/var/log/router.log")

This is using the latest rsyslog configuration method: a handy scripting language called RainerScript. Severity level 5 maps to "notice" which consists of unusual non-error conditions, and is of course the IP address of the router on the LAN side. With this, I'm directing all router log messages to a separate file, filtering out anything less important than severity 5.

In order for rsyslog to pick up this new configuration file, I restarted it:

systemctl restart rsyslog.service

and checked that it was running correctly (e.g. no syntax errors in the new config file) using:

systemctl status rsyslog.service

Since I added a new log file, I also setup log rotation for it by putting the following in /etc/logrotate.d/router:

    rotate 4

In addition, since I use logcheck to monitor my server logs and email me errors, I had to add /var/log/router.log to /etc/logcheck/logcheck.logfiles.

Finally I opened the rsyslog port to the router in my server's firewall by adding the following to /etc/network/iptables.up.rules:

# Allow logs from the router
-A INPUT -s -p tcp --dport 514 -j ACCEPT

and ran iptables-apply.

With all of this in place, it was time to get the router to send messages.

Router setup

As suggested on the Turris forum, I ssh'ed into my router and added this in /etc/syslog-ng.d/remote.conf:

destination d_loghost {
        network("" time-zone("America/Vancouver"));

source dns {

log {

Setting the timezone to the same as my server was needed because the router messages were otherwise sent with UTC timestamps.

To ensure that the destination host always gets the same IP address (, I went to the advanced DHCP configuration page and added a static lease for the server's MAC address so that it always gets assigned If that wasn't already the server's IP address, you'll have to restart it for this to take effect.

Finally, I restarted the syslog-ng daemon on the router to pick up the new config file:

/etc/init.d/syslog-ng restart


In order to test this configuration, I opened three terminal windows:

  1. tail -f /var/log/syslog on the server
  2. tail -f /var/log/router.log on the server
  3. tail -f /var/log/messages on the router

I immediately started to see messages from the router in the third window and some of these, not all because of my severity-5 filter, were flowing to the second window as well. Also important is that none of the messages make it to the first window, otherwise log messages from the router would be mixed in with the server's own logs. That's the purpose of the stop command in /etc/rsyslog.d/router.conf.

To force a log messages to be emitted by the router, simply ssh into it and issue the following command:

logger Test

It should show up in the second and third windows immediately if you've got everything setup correctly

Timezone problems

If I do the following on my router:

/etc/init.d/syslog-ng restart logger TestA

I see the following in /var/log/messages:

Aug 14 20:39:35 hostname syslog-ng[9860]: syslog-ng shutting down; version='3.37.1' Aug 14 20:39:36 hostname syslog-ng[10024]: syslog-ng starting up; version='3.37.1' Aug 15 03:39:49 hostname root: TestA

The correct timezone is the one in the first two lines. Other daemon messages are displayed using an incorrect timezone like logger.

Thanks to a very helpful syslog-ng mailing list thread, I found that this is actually an upstream OpenWRT bug.

My favourite work-around is to tell syslog-ng to simply ignore the timestamp provided by the application and to use the time of reception (of the log message) instead. To do this, simply change the following in /etc/syslog-ng.conf:

source src {


source src {
    unix-dgram("/dev/log", keep-timestamp(no));

Unfortunately, I wasn't able to fix it in a way that would survive a syslog-ng package update, but since this is supposedly fixed in Turris 6.0, it shouldn't be a problem for much longer.

28 October, 2023 11:54PM

October 26, 2023

Dima Kogan

Talking to ROS from outside a LAN

The problem

This is about ROS version 1. Version 2 is different, and maybe they fixed stuff. But I kinda doubt it since this thing is heinous in a million ways.

Alright so let's say we have have some machines in a LAN doing ROS stuff and we have another machine outside the LAN that wants to listen in (like to get a realtime visualization, say). This is an extremely common scenario, but they created enough hoops to make this not work. Let's say we have 3 computers:

  • router: the bridge between the two networks. This has two NICs. The inner IP is and the outer IP is
  • inner: a machine in the LAN that's doing ROS stuff. IP
  • outer: a machine outside that LAN that wants to listen in. IP

Let's say the router is doing ROS stuff. It's running the ROS master and some nodes like this:

ROS_IP= roslaunch whatever

If you omit the ROS_IP it'll pick router, which may or may not work, depending on how the DNS is set up. Here we set it to to make it possible for the inner machine to communicate (we'll see why in a bit). An aside: ROS should use the IP by default instead of the name because the IP will work even if the DNS isn't set up. If there are multiple extant IPs, it should throw an error. But all that would be way too user-friendly.

OK. So we have a ROS master on on the default port: 11311. The inner machine can rostopic echo and all that. Great.

What if I try to listen in from outer? I say

ROS_MASTER_URI= rostopic list

This connects to the router on that port, and it works well: I get the list of available topics. Here this works because the router is the router. If inner was running the ROS master then we'd need to do a forward for port 11311. In any case, this works and we understand it.

So clearly we can talk to the ROS master. Right? Wrong! Let's actually listen in on a specific topic on outer:

ROS_MASTER_URI= rostopic echo /some/topic

This does not work. No errors are reported. It just sits there, which looks like no data is coming in on that topic. But this is a lie: it's actually broken.

The diagnosis

So this is our problem. It's a very common use case, and there are plenty of internet people asking about it, with no specific solutions. I debugged it, and the details are here.

To figure out what's going on, I made a syscall log on a machine inside the LAN, where a simple rostopic echo does work:

sysdig -A proc.name=rostopic and fd.type contains ipv -s 2000

This shows us all the communication between inner running rostopic and the server. It's really chatty. It's all TCP. There are multiple connections to the router on port 11311. It also starts up multiple TCP servers on the client that listen to connections; these are likely to be broken if we were running the client on outer and a machine inside the LAN tried to talk to them; but thankfully in my limited testing nothing actually tried to talk to them. The conversations on port 11311 are really long, but here's the punchline.

inner tells the router:

POST /RPC2 HTTP/1.1                                                                                                                 
Accept-Encoding: gzip                                                                                                               
Content-Type: text/xml                                                                                                              
User-Agent: Python-xmlrpc/3.11                                                                                                      
Content-Length: 390                                                                                                                 

<?xml version='1.0'?>

Yes. It's laughably chatty. Then the router replies:

HTTP/1.1 200 OK
Server: BaseHTTP/0.6 Python/3.8.10
Date: Thu, 26 Oct 2023 23:15:28 GMT
Content-type: text/xml
Content-length: 342

<?xml version='1.0'?>
<value><string>Subscribed to [/some/topic]</string></value>

Then this sequence of system calls happens in the rostopic process (an excerpt from the sysdig log):

> connect fd=10(<4>) addr=
< connect res=-115(EINPROGRESS) tuple=> fd=10(<4t>>
< getsockopt res=0 fd=10(<4t>> level=1(SOL_SOCKET) optname=4(SO_ERROR) val=0 optlen=4

So the inner client makes an outgoing TCP connection on the address given to it by the ROS master above: This IP is only accessible from within the LAN, which works fine when talking to it from inner, but would be a problem from the outside. Furthermore, some sort of single-port-forwarding scheme wouldn't fix connecting from outer either, since the port number is dynamic.

To confirm what we think is happening, the sequence of syscalls when trying to rostopic echo from outer does indeed fail:

connect fd=10(<4>) addr= 
connect res=-115(EINPROGRESS) tuple=> fd=10(<4t>>
getsockopt res=0 fd=10(<4t>> level=1(SOL_SOCKET) optname=4(SO_ERROR) val=-111(ECONNREFUSED) optlen=4

That's the breakage mechanism: the ROS master asks us to communicate on an address we can't talk to.

Debugging this is easy with sysdig:

sudo sysdig -A -s 400 evt.buffer contains '"Subscribed to"' and proc.name=rostopic

This prints out all syscalls seen by the rostopic command that contain the string Subscribed to, so you can see that different addresses the ROS master gives us in response to different commands.

OK. So can we get the ROS master to give us an address that we can actually talk to? Sorta. Remember that we invoked the master with

ROS_IP= roslaunch whatever

The ROS_IP environment variable is exactly the address that the master gives out. So in this case, we can fix it by doing this instead:

ROS_IP= roslaunch whatever

Then the outer machine will be asked to talk to, which works. Unfortunately, if we do that, then the inner machine won't be able to communicate.

So some sort of ssh port forward cannot fix this: we need a lower-level tunnel, like a VPN or something.

And another rant. Here rostopic tried to connect to an unreachable address, which failed. But rostopic knows the connection failed! It should throw an error message to the user. Something like this would be wonderful:

ERROR! Tried to connect to ($ROS_IP:dynamicport), but connect() returned ECONNREFUSED

That would be immensely helpful. It would tell the user that something went wrong (instead of no data being sent), and it would give a strong indication of the problem and how to fix it. But that would be asking too much.

The solution

So we need a VPN-like thing. I just tried sshuttle, and it just works.

Start the ROS node in the way that makes connections from within the LAN work:

ROS_IP= roslaunch whatever

Then on the outer client:

sshuttle -r router

This connects to the router over ssh and does some hackery to make all connections from outer to 10.0.1.x transparently route into the LAN. On all ports. rostopic echo then works. I haven't done any thorough testing, but hopefully it's reliable and has low overhead; I don't know.

I haven't tried it but almost certainly this would work even with the ROS master running on inner. This would be accomplished like this:

  1. Tell ssh how to connect to inner. Dropping this into ~/.ssh/config should do it:
    Host inner
    ProxyJump router
  2. Do the magic thing:
    sshuttle -r inner

I'm sure any other VPN-like thing would work also.

26 October, 2023 11:25PM by Dima Kogan

hackergotchi for Jonathan McDowell

Jonathan McDowell

PSA: OpenPGP key updated in Debian keyring

This is a Public Service Announcement that my new OpenPGP key has now been updated in the active Debian keyring. I believe the only team that needs to be informed about this to manually update their systems is DSA, and I’ve filed an RT ticket to give them a heads up.

Thanks to all the folk who signed my new key, both at the Debian UK BBQ, and DebConf.

26 October, 2023 08:53PM

October 25, 2023

hackergotchi for Phil Hands

Phil Hands

Sleep Apnoea

I just noticed that I wrote this a decade ago, and then never got round to posting it, so thought I might kick it off now to mark my tentative return to blogging.

At the recent 2015 Cambridge-UK Mini-DebConf (generously hosted by ARM), I gave an impromptu Lightning Talk about Sleep Apnoea (video here).

Obstructive Sleep Apnoea (OSA - the form I'm on about) is a sleep disorder where one repeatedly stops breathing while asleep, normally when snoring, but not necessarily. The consequence of this is that in order to resume breathing one must wake up momentarily. These events are not remembered, but they ruin the quality of your sleep.

If you find that you're often quite tired, you should probably give the Epworth Sleepiness Scale a try -- if it suggests you have a problem: Get thee to a doctor for a check-up!

The good news is that if you do turn out to have OSA it's fairly easy to treat (CPAP or more recently APAP being the favoured treatment), and that when treated you should be able to get good quality sleep that will result in you being much more awake, and much more cheerful.

If you might be an Apnoeac (or a sufferer of some other sleep disorder, for that matter), get yourself treated, and you'll be able to use the extra hours of daily concentration working on Debian, thus making the world a better place :-)

25 October, 2023 10:44PM

Sven Hoexter

Curing vpnc-scripts Symptoms

I stick to some very archaic workflows, e.g. to connect to some corp VPN I just run sudo vpnc-connect and later on sudo vpnc-disconnect. In the past that also managed to restore my resolv.conf, currently it doesn't. According to a colleague that's also the case for Ubuntu.

Taking a step back, the sane way would be to use the NetworkManager vpnc plugin, but that does not work with this specific case because we use uncool VPN tech which requires the Enable weak authentication setting for vpnc. There is a feature request open for that one at https://gitlab.gnome.org/GNOME/NetworkManager-vpnc/-/issues/11

Taking another step back I thought that it shouldn't be that hard to add some checkbox, a boolean and render out another config flag or line in a config file. Not as intuitive as I thought this mix of XML and C. So let's quickly look elsewhere.

What happens is that the backup files in /var/run/vpnc/ are created by the vpnc-scripts script called vpnc-script, but not moved back, because it adds some pid as a suffix and the pid is not the final pid of the vpnc process. Basically it can not find the backup when it tries to restore it. So I decided to replace the pid guessing code with a suffix made up of the gateway IP and the tun interface name. No idea if that is stable in all circumstance (someone with a vpn name DNS RR?) or several connections to different gateways. But good enough for myself, so here is my patch:

vpnc-scripts [master]$ cat debian/patches/replace-pid-detection 
Index: vpnc-scripts/vpnc-script
--- vpnc-scripts.orig/vpnc-script
+++ vpnc-scripts/vpnc-script
@@ -91,21 +91,15 @@ OS="`uname -s`"


-# Use the PID of the controlling process (vpnc or OpenConnect) to
-# uniquely identify this VPN connection. Normally, the parent process
-# is a shell, and the grandparent's PID is the relevant one.
-# OpenConnect v9.0+ provides VPNPID, so we don't need to determine it.
-if [ -z "$VPNPID" ]; then
-    PCMD=`ps -c -o cmd= -p $PPID`
-    case "$PCMD" in
-        *sh) VPNPID=`ps -o ppid= -p $PPID` ;;
-    esac
+# This whole script is called twice via vpnc-connect. On the first run
+# the variables are empty. Catch that and move on when they're there.
+if [ -n "$VPNGATEWAY" ]; then
+    DEFAULT_ROUTE_FILE=/var/run/vpnc/defaultroute.${BACKUPID}
+    DEFAULT_ROUTE_FILE_IPV6=/var/run/vpnc/defaultroute_ipv6.${BACKUPID}
+    RESOLV_CONF_BACKUP=/var/run/vpnc/resolv.conf-backup.${BACKUPID}

 SCRIPTNAME=`basename $0`

 # some systems, eg. Darwin & FreeBSD, prune /var/run on boot

Or rolled into a debian package at https://sven.stormbind.net/debian/vpnc-scripts/

The colleague decided to stick to NetworkManager, moved the vpnc binary aside and added a wrapper which invokes vpnc with --enable-weak-authentication. The beauty is, all of this will break on updates, so at some point someone has to understand GTK4 to fix the NetworkManager plugin for good. :)

25 October, 2023 02:15PM

Russ Allbery

Review: Going Infinite

Review: Going Infinite, by Michael Lewis

Publisher: W.W. Norton & Company
Copyright: 2023
ISBN: 1-324-07434-5
Format: Kindle
Pages: 255

My first reaction when I heard that Michael Lewis had been embedded with Sam Bankman-Fried working on a book when Bankman-Fried's cryptocurrency exchange FTX collapsed into bankruptcy after losing billions of dollars of customer deposits was "holy shit, why would you talk to Michael Lewis about your dodgy cryptocurrency company?" Followed immediately by "I have to read this book."

This is that book.

I wasn't sure how Lewis would approach this topic. His normal (although not exclusive) area of interest is financial systems and crises, and there is lots of room for multiple books about cryptocurrency fiascoes using someone like Bankman-Fried as a pivot. But Going Infinite is not like The Big Short or Lewis's other financial industry books. It's a nearly straight biography of Sam Bankman-Fried, with just enough context for the reader to follow his life.

To understand what you're getting in Going Infinite, I think it's important to understand what sort of book Lewis likes to write. Lewis is not exactly a reporter, although he does explain complicated things for a mass audience. He's primarily a storyteller who collects people he finds fascinating. This book was therefore never going to be like, say, Carreyrou's Bad Blood or Isaac's Super Pumped. Lewis's interest is not in a forensic account of how FTX or Alameda Research were structured. His interest is in what makes Sam Bankman-Fried tick, what's going on inside his head.

That's not a question Lewis directly answers, though. Instead, he shows you Bankman-Fried as Lewis saw him and was able to reconstruct from interviews and sources and lets you draw your own conclusions. Boy did I ever draw a lot of conclusions, most of which were highly unflattering. However, one conclusion I didn't draw, and had been dubious about even before reading this book, was that Sam Bankman-Fried was some sort of criminal mastermind who intentionally plotted to steal customer money. Lewis clearly doesn't believe this is the case, and with the caveat that my study of the evidence outside of this book has been spotty and intermittent, I think Lewis has the better of the argument.

I am utterly fascinated by this, and I'm afraid this review is going to turn into a long summary of my take on the argument, so here's the capsule review before you get bored and wander off: This is a highly entertaining book written by an excellent storyteller. I am also inclined to believe most of it is true, but given that I'm not on the jury, I'm not that invested in whether Lewis is too credulous towards the explanations of the people involved. What I do know is that it's a fantastic yarn with characters who are too wild to put in fiction, and I thoroughly enjoyed it.

There are a few things that everyone involved appears to agree on, and therefore I think we can take as settled. One is that Bankman-Fried, and most of the rest of FTX and Alameda Research, never clearly distinguished between customer money and all of the other money. It's not obvious that their home-grown accounting software (written entirely by one person! who never spoke to other people! in code that no one else could understand!) was even capable of clearly delineating between their piles of money. Another is that FTX and Alameda Research were thoroughly intermingled. There was no official reporting structure and possibly not even a coherent list of employees. The environment was so chaotic that lots of people, including Bankman-Fried, could have stolen millions of dollars without anyone noticing. But it was also so chaotic that they could, and did, literally misplace millions of dollars by accident, or because Bankman-Fried had problems with object permanence.

Something that was previously less obvious from news coverage but that comes through very clearly in this book is that Bankman-Fried seriously struggled with normal interpersonal and societal interactions. We know from multiple sources that he was diagnosed with ADHD and depression (Lewis describes it specifically as anhedonia, the inability to feel pleasure). The ADHD in Lewis's account is quite severe and does not sound controlled, despite medication; for example, Bankman-Fried routinely played timed video games while he was having important meetings, forgot things the moment he stopped dealing with them, was constantly on his phone or seeking out some other distraction, and often stimmed (by bouncing his leg) to a degree that other people found it distracting.

Perhaps more tellingly, Bankman-Fried repeatedly describes himself in diary entries and correspondence to other people (particularly Caroline Ellison, his employee and on-and-off secret girlfriend) as being devoid of empathy and unable to access his own emotions, which Lewis supports with stories from former co-workers. I'm very hesitant to diagnose someone via a book, but, at least in Lewis's account, Bankman-Fried nearly walks down the symptom list of antisocial personality disorder in his own description of himself to other people. (The one exception is around physical violence; there is nothing in this book or in any of the other reporting that I've seen to indicate that Bankman-Fried was violent or physically abusive.) One of the recurrent themes of this book is that Bankman-Fried never saw the point in following rules that didn't make sense to him or worrying about things he thought weren't important, and therefore simply didn't.

By about a third of the way into this book, before FTX is even properly started, very little about its eventual downfall will seem that surprising. There was no way that Sam Bankman-Fried was going to be able to run a successful business over time. He was extremely good at probabilistic trading and spotting exploitable market inefficiencies, and extremely bad at essentially every other aspect of living in a society with other people, other than a hit-or-miss ability to charm that worked much better with large audiences than one-on-one. The real question was why anyone would ever entrust this man with millions of dollars or decide to work for him for longer than two weeks.

The answer to those questions changes over the course of this story. Later on, it was timing. Sam Bankman-Fried took the techniques of high frequency trading he learned at Jane Street Capital and applied them to exploiting cryptocurrency markets at precisely the right time in the cryptocurrency bubble. There was far more money than sense, the most ruthless financial players were still too leery to get involved, and a rising tide was lifting all boats, even the ones that were piles of driftwood. When cryptocurrency inevitably collapsed, so did his businesses. In retrospect, that seems inevitable.

The early answer, though, was effective altruism.

A full discussion of effective altruism is beyond the scope of this review, although Lewis offers a decent introduction in the book. The short version is that a sensible and defensible desire to use stronger standards of evidence in evaluating charitable giving turned into a bizarre navel-gazing exercise in making up statistical risks to hypothetical future people and treating those made-up numbers as if they should be the bedrock of one's personal ethics. One of the people most responsible for this turn is an Oxford philosopher named Will MacAskill. Sam Bankman-Fried was already obsessed with utilitarianism, in part due to his parents' philosophical beliefs, and it was a presentation by Will MacAskill that converted him to the effective altruism variant of extreme utilitarianism.

In Lewis's presentation, this was like joining a cult. The impression I came away with feels like something out of a science fiction novel: Bankman-Fried knew there was some serious gap in his thought processes where most people had empathy, was deeply troubled by this, and latched on to effective altruism as the ethical framework to plug into that hole. So much of effective altruism sounds like a con game that it's easy to think the participants are lying, but Lewis clearly believes Bankman-Fried is a true believer. He appeared to be sincerely trying to make money in order to use it to solve existential threats to society, he does not appear to be motivated by money apart from that goal, and he was following through (in bizarre and mostly ineffective ways).

I find this particularly believable because effective altruism as a belief system seems designed to fit Bankman-Fried's personality and justify the things he wanted to do anyway. Effective altruism says that empathy is meaningless, emotion is meaningless, and ethical decisions should be made solely on the basis of expected value: how much return (usually in safety) does society get for your investment. Effective altruism says that all the things that Sam Bankman-Fried was bad at were useless and unimportant, so he could stop feeling bad about his apparent lack of normal human morality. The only thing that mattered was the thing that he was exceptionally good at: probabilistic reasoning under uncertainty. And, critically to the foundation of his business career, effective altruism gave him access to investors and a recruiting pool of employees, things he was entirely unsuited to acquiring the normal way.

There's a ton more of this book that I haven't touched on, but this review is already quite long, so I'll leave you with one more point.

I don't know how true Lewis's portrayal is in all the details. He took the approach of getting very close to most of the major players in this drama and largely believing what they said happened, supplemented by startling access to sources like Bankman-Fried's personal diary and Caroline Ellis's personal diary. (He also seems to have gotten extensive information from the personal psychiatrist of most of the people involved; I'm not sure if there's some reasonable explanation for this, but based solely on the material in this book, it seems to be a shocking breach of medical ethics.) But Lewis is a storyteller more than he's a reporter, and his bias is for telling a great story. It's entirely possible that the events related here are not entirely true, or are skewed in favor of making a better story. It's certainly true that they're not the complete story.

But, that said, I think a book like this is a useful counterweight to the human tendency to believe in moral villains. This is, frustratingly, a counterweight extended almost exclusively to higher-class white people like Bankman-Fried. This is infuriating, but that doesn't make it wrong. It means we should extend that analysis to more people.

Once FTX collapsed, a lot of people became very invested in the idea that Bankman-Fried was a straightforward embezzler. Either he intended from the start to steal everyone's money or, more likely, he started losing money, panicked, and stole customer money to cover the hole. Lots of people in history have done exactly that, and lots of people involved in cryptocurrency have tenuous attachments to ethics, so this is a believable story. But people are complicated, and there's also truth in the maxim that every villain is the hero of their own story. Lewis is after a less boring story than "the crook stole everyone's money," and that leads to some bias. But sometimes the less boring story is also true.

Here's the thing: even if Sam Bankman-Fried never intended to take any money, he clearly did intend to mix customer money with Alameda Research funds. In Lewis's account, he never truly believed in them as separate things. He didn't care about following accounting or reporting rules; he thought they were boring nonsense that got in his way. There is obvious criminal intent here in any reading of the story, so I don't think Lewis's more complex story would let him escape prosecution. He refused to follow the rules, and as a result a lot of people lost a lot of money. I think it's a useful exercise to leave mental space for the possibility that he had far less obvious reasons for those actions than that he was a simple thief, while still enforcing the laws that he quite obviously violated.

This book was great. If you like Lewis's style, this was some of the best entertainment I've read in a while. Highly recommended; if you are at all interested in this saga, I think this is a must-read.

Rating: 9 out of 10

25 October, 2023 03:08AM

October 24, 2023

Iustin Pop

OS updates are damn easy nowadays!

I’m baffled at how simple and reliable operating system updates have become.

Upgraded Debian bullseye to bookworm, across a few systems, easy. On VMs, it’s even so fast that installing base system from scratch is probably the same time.

But Linux/Debian OFC works well. Shall we look at MacOS? Takes longer, but just runs and reboots a couple of times and then, bam, it’s up and with windows restored.

Surely Windows is the outlier? Nah, finally said yes to the “Upgrade to Win 11?� prompt, and it took a while to download (why is Win/Mac so heavy and slow to download? Debian just flies!), then rebooted a few times, and again, bam, it’s up and GoG and Steam still work.

I swear, there was a time when updating the OS felt like an accomplishment. Now, except for Raspberry Pi OS (“upgrades not supported, reinstall!� but I bet they also work), upgrading an actual OS is just like new Android/iOS version.

And yes, get off my lawn! I still have a lower digit count Slashdot ID 😅

24 October, 2023 08:20PM

October 23, 2023

Russell Coker

Bluetooth Versions and PineTime

I’ve done some tests with the PineTime [1] on different Android phones. On a Huawei Mate 10 Pro (from 2017 with Bluetooth 4.2) it has very slow transfer speeds for updating the firmware (less than 1KB/s) and unreliable connection to the phone. On a Huawei Nova 7i (from 2020 with Bluetooth 4.2) it has slow transfer speeds (about 2KB/s) and a more reliable connection to the phone. On a Pixel 4 XL (from 2019 with Bluetooth 5.0) it has very fast speeds for updating the firmware and also a reliable link.

Version 5 of the Bluetooth standard [2] was released in 2016 so it’s a little disappointing that the Mate 10 Pro doesn’t support it and very disappointing that the Nova 7i doesn’t support it either. Bluetooth 5 adds higher speeds and longer range for LE (Low Energy) modes which are used for things like smart watches.

It’s extremely disappointing that the PinePhonePro [3] only supports Bluetooth 4.1. It’s a phone released in 2021 that doesn’t even have Bluetooth 4.2 which was released in 2014.

For laptops the Thinkpad X1 Carbon 7th Gen release in 2019 [4] was the first in the X1 Carbon series to have Bluetooth 5. So I will probably be limited in my ability to use my personal laptop or PinePhone for testing Linux software that talks to the PineTime and I’ll have to use a laptop borrowed from work.

23 October, 2023 11:40AM by etbe

Russ Allbery

Review: Going Postal

Review: Going Postal, by Terry Pratchett

Series: Discworld #33
Publisher: Harper
Copyright: October 2004
Printing: November 2014
ISBN: 0-06-233497-2
Format: Mass market
Pages: 471

Going Postal is the 33rd Discworld novel. You could probably start here if you wanted to; there are relatively few references to previous books, and the primary connection (to Feet of Clay) is fully re-explained. I suspect that's why Going Postal garnered another round of award nominations. There are arguable spoilers for Feet of Clay, however.

Moist von Lipwig is a con artist. Under a wide variety of names, he's swindled and forged his way around the Disc, always confident that he can run away from or talk his way out of any trouble. As Going Postal begins, however, it appears his luck has run out. He's about to be hanged.

Much to his surprise, he wakes up after his carefully performed hanging in Lord Vetinari's office, where he's offered a choice. He can either take over the Ankh-Morpork post office, or he can die. Moist, of course, immediately agrees to run the post office, and then leaves town at the earliest opportunity, only to be carried back into Vetinari's office by a relentlessly persistent golem named Mr. Pump. He apparently has a parole officer.

The clacks, Discworld's telegraph system first seen in The Fifth Elephant, has taken over most communications. The city is now dotted with towers, and the Grand Trunk can take them at unprecedented speed to even far-distant cities like Genua. The post office, meanwhile, is essentially defunct, as Moist quickly discovers. There are two remaining employees, the highly eccentric Junior Postman Groat who is still Junior because no postmaster has lasted long enough to promote him, and the disturbingly intense Apprentice Postman Stanley, who collects pins.

Other than them, the contents of the massive post office headquarters are a disturbing mail sorting machine designed by Bloody Stupid Johnson that is not picky about which dimension or timeline the sorted mail comes from, and undelivered mail. A lot of undelivered mail. Enough undelivered mail that there may be magical consequences.

All Moist has to do is get the postal system running again. Somehow. And not die in mysterious accidents like the previous five postmasters.

Going Postal is a con artist story, but it's also a startup and capitalism story. Vetinari is, as always, solving a specific problem in his inimitable indirect way. The clacks were created by engineers obsessed with machinery and encodings and maintenance, but it's been acquired by... well, let's say private equity, because that's who they are, although Discworld doesn't have that term. They immediately did what private equity always did: cut out everything that didn't extract profit, without regard for either the service or the employees. Since the clacks are an effective monopoly and the new owners are ruthless about eliminating any possible competition, there isn't much to stop them. Vetinari's chosen tool is Moist.

There are some parts of this setup that I love and one part that I'm grumbly about. A lot of the fun of this book is seeing Moist pulled into the mission of resurrecting the post office despite himself. He starts out trying to wriggle out of his assigned task, but, after a few early successes and a supernatural encounter with the mail, he can't help but start to care. Reformed con men often make good protagonists because one can enjoy the charisma without disliking the ethics. Pratchett adds the delightfully sharp-witted and cynical Adora Belle Dearheart as a partial reader stand-in, which makes the process of Moist becoming worthy of his protagonist role even more fun.

I think that a properly functioning postal service is one of the truly monumental achievements of human society and doesn't get nearly enough celebration (or support, or pay, or good working conditions). Give me a story about reviving a postal service by someone who appreciates the tradition and social role as much as Pratchett clearly does and I'm there. The only frustration is that Going Postal is focused more on an immediate plot, so we don't get to see the larger infrastructure recovery that is clearly needed. (Maybe in later books?)

That leads to my grumble, though. Going Postal and specifically the takeover of the clacks is obviously inspired by corporate structures in the later Industrial Revolution, but this book was written in 2004, so it's also a book about private equity and startups. When Vetinari puts a con man in charge of the post office, he runs it like a startup: do lots of splashy things to draw attention, promise big and then promise even bigger, stumble across a revenue source that may or may not be sustainable, hire like mad, and hope it all works out.

This makes for a great story in the same way that watching trapeze artists or tightrope walkers is entertaining. You know it's going to work because that's the sort of book you're reading, so you can enjoy the audacity and wonder how Moist will manage to stay ahead of his promises. But it is still a con game applied to a public service, and the part of me that loves the concept of the postal service couldn't stop feeling like this is part of the problem.

The dilemma that Vetinari is solving is a bit too realistic, down to the requirement that the post office be self-funding and not depend on city funds and, well, this is repugnant to me. Public services aren't businesses. Societies spend money to build things that they need to maintain society, and postal service is just as much one of those things as roads are. The ability of anyone to send a letter to anyone else, no matter how rural the address is, provides infrastructure on which a lot of important societal structure is built. Pratchett made me care a great deal about Ankh-Morpork's post office (not hard to do), and now I want to see it rebuilt properly, on firm foundations, without splashy promises and without a requirement that it pay for itself. Which I realize is not the point of Discworld at all, but the concept of running a postal service like a startup hits maybe a bit too close to home.

Apart from that grumble, this is a great book if you're in the mood for a reformed con man story. I thought the gold suit was a bit over the top, but I otherwise thought Moist's slow conversion to truly caring about his job was deeply satisfying. The descriptions of the clacks are full of askew Discworld parodies of computer networking and encoding that I enjoyed more than I thought I would. This is also the book that introduced the now-famous (among Pratchett fans at least) GNU instruction for the clacks, and I think that scene is the most emotionally moving bit of Pratchett outside of Night Watch.

Going Postal is one of the better books in the Discworld series to this point (and I'm sadly getting near the end). If you have less strongly held opinions about management and funding models for public services, or at least are better at putting them aside when reading fantasy novels, you're likely to like it even more than I did. Recommended.

Followed by Thud!. The thematic sequel is Making Money.

Rating: 8 out of 10

23 October, 2023 03:54AM

October 22, 2023

hackergotchi for Steinar H. Gunderson

Steinar H. Gunderson

Some defaults I don't understand

I'll rant about just one in mpv today: Why would you not have hardware decoding be default, if it's available? Is that really the best thing for a user who hasn't given a preference?

You should never just copy someone's defaults uncritically, but here is my HTPC's ~/.config/mpv/mpv.conf for reference:


22 October, 2023 05:57PM

Ian Jackson

DigiSpark (ATTiny85) - Arduino, C, Rust, build systems

Recently I completed a small project, including an embedded microcontroller. For me, using the popular Arduino IDE, and C, was a mistake. The experience with Rust was better, but still very exciting, and not in a good way.

Here follows the rant.


In a recent project (I’ll write about the purpose, and the hardware in another post) I chose to use a DigiSpark board. This is a small board with a USB-A tongue (but not a proper plug), and an ATTiny85 microcontroller, This chip has 8 pins and is quite small really, but it was plenty for my application. By choosing something popular, I hoped for convenient hardware, and an uncomplicated experience.

Convenient hardware, I got.

Arduino IDE

The usual way to program these boards is via an IDE. I thought I’d go with the flow and try that. I knew these were closely related to actual Arduinos and saw that the IDE package arduino was in Debian.

But it turns out that the Debian package’s version doesn’t support the DigiSpark. (AFAICT from the list it offered me, I’m not sure it supports any ATTiny85 board.) Also, disturbingly, its “board manager” seemed to be offering to “install” board support, suggesting it would download “stuff” from the internet and run it. That wouldn’t be acceptable for my main laptop.

I didn’t expect to be doing much programming or debugging, and the project didn’t have significant security requirements: the chip, in my circuit, has only a very narrow ability do anything to the real world, and no network connection of any kind. So I thought it would be tolerable to do the project on my low-security “video laptop”. That’s the machine where I’m prepared to say “yes” to installing random software off the internet.

So I went to the upstream Arduino site and downloaded a tarball containing the Arduino IDE. After unpacking that in /opt it ran and produced a pointy-clicky IDE, as expected. I had already found a 3rd-party tutorial saying I needed to add a magic URL (from the DigiSpark’s vendor) in the preferences. That indeed allowed it to download a whole pile of stuff. Compilers, bootloader clients, god knows what.

However, my tiny test program didn’t make it to the board. Half-buried in a too-small window was an error message about the board’s bootloader (“Micronucleus”) being too new.

The boards I had came pre-flashed with micronucleus 2.2. Which is hardly new, But even so the official Arduino IDE (or maybe the DigiSpark’s board package?) still contains an old version. So now we have all the downsides of curl|bash-ware, but we’re lacking the “it’s up to date” and “it just works” upsides.

Further digging found some random forum posts which suggested simply downloading a newer micronucleus and manually stuffing it into the right place: one overwrites a specific file, in the middle the heaps of stuff that the Arduino IDE’s board support downloader squirrels away in your home directory. (In my case, the home directory of the untrusted shared user on the video laptop,)

So, “whatever”. I did that. And it worked!

Having demo’d my ability to run code on the board, I set about writing my program.

Writing C again

The programming language offered via the Arduino IDE is C.

It’s been a little while since I started a new thing in C. After having spent so much of the last several years writing Rust. C’s primitiveness quickly started to grate, and the program couldn’t easily be as DRY as I wanted (Don’t Repeat Yourself, see Wilson et al, 2012, §4, p.6). But, I carried on; after all, this was going to be quite a small job.

Soon enough I had a program that looked right and compiled.

Before testing it in circuit, I wanted to do some QA. So I wrote a simulator harness that #included my Arduino source file, and provided imitations of the few Arduino library calls my program used. As an side advantage, I could build and run the simulation on my main machine, in my normal development environment (Emacs, make, etc.). The simulator runs confirmed the correct behaviour. (Perhaps there would have been some more faithful simulation tool, but the Arduino IDE didn’t seem to offer it, and I wasn’t inclined to go further down that kind of path.)

So I got the video laptop out, and used the Arduino IDE to flash the program. It didn’t run properly. It hung almost immediately. Some very ad-hoc debugging via led-blinking (like printf debugging, only much worse) convinced me that my problem was as follows:

Arduino C has 16-bit ints. My test harness was on my 64-bit Linux machine. C was autoconverting things (when building for the micrcocontroller). The way the Arduino IDE ran the compiler didn’t pass the warning options necessary to spot narrowing implicit conversions. Those warnings aren’t the default in C in general because C compilers hate us all for compatibility reasons.

I don’t know why those warnings are not the default in the Arduino IDE, but my guess is that they didn’t want to bother poor novice programmers with messages from the compiler explaining how their program is quite possibly wrong. After all, users don’t like error messages so we shouldn’t report errors. And novice programmers are especially fazed by error messages so it’s better to just let them struggle themselves with the arcane mysteries of undefined behaviour in C?

The Arduino IDE does offer a dropdown for “compiler warnings”. The default is None. Setting it to All didn’t produce anything about my integer overflow bugs. And, the output was very hard to find anyway because the “log” window has a constant stream of strange messages from javax.jmdns, with hex DNS packet dumps. WTF.

Other things that were vexing about the Arduino IDE: it has fairly fixed notions (which don’t seem to be documented) about how your files and directories ought to be laid out, and magical machinery for finding things you put “nearby” its “sketch” (as it calls them) and sticking them in its ear, causing lossage. It has a tendency to become confused if you edit files under its feet (e.g. with git checkout). It wasn’t really very suited to a workflow where principal development occurs elsewhere.

And, important settings such as the project’s clock speed, or even the target board, or the compiler warning settings to use weren’t stored in the project directory along with the actual code. I didn’t look too hard, but I presume they must be in a dotfile somewhere. This is madness.

Apparently there is an Arduino CLI too. But I was already quite exasperated, and I didn’t like the idea of going so far off the beaten path, when the whole point of using all this was to stay with popular tooling and share fate with others. (How do these others cope? I have no idea.)

As for the integer overflow bug:

I didn’t seriously consider trying to figure out how to control in detail the C compiler options passed by the Arduino IDE. (Perhaps this is possible, but not really documented?) I did consider trying to run a cross-compiler myself from the command line, with appropriate warning options, but that would have involved providing (or stubbing, again) the Arduino/DigiSpark libraries (and bugs could easily lurk at that interface).

Instead, I thought, “if only I had written the thing in Rust”. But that wasn’t possible, was it? Does Rust even support this board?

Rust on the DigiSpark

I did a cursory web search and found a very useful blog post by Dylan Garrett.

This encouraged me to think it might be a workable strategy. I looked at the instructions there. It seemed like I could run them via the privsep arrangement I use to protect myself when developing using upstream cargo packages from crates.io.

I got surprisingly far surprisingly quickly. It did, rather startlingly, cause my rustup to download a random recent Nightly Rust, but I have six of those already for other Reasons. Very quickly I got the “trinket” LED blink example, referenced by Dylan’s blog post, to compile. Manually copying the file to the video laptop allowed me to run the previously-downloaded micronucleus executable and successfully run the blink example on my board!

I thought a more principled approach to the bootloader client might allow a more convenient workflow. I found the upstream Micronucleus git releases and tags, and had a look over its source code, release dates, etc. It seemed plausible, so I compiled v2.6 from source. That was a success: now I could build and install a Rust program onto my board, from the command line, on my main machine. No more pratting about with the video laptop.

I had got further, more quickly, with Rust, than with the Arduino IDE, and the outcome and workflow was superior.

So, basking in my success, I copied the directory containing the example into my own project, renamed it, and adjusted the path references.

That didn’t work. Now it didn’t build. Even after I copied about .cargo/config.toml and rust-toolchain.toml it didn’t build, producing a variety of exciting messages, depending what precisely I tried. I don’t have detailed logs of my flailing: the instructions say to build it by cd’ing to the subdirectory, and, given that what I was trying to do was to not follow those instructions, it didn’t seem sensible to try to prepare a proper repro so I could file a ticket. I wasn’t optimistic about investigating it more deeply myself: I have some experience of fighting cargo, and it’s not usually fun. Looking at some of the build control files, things seemed quite complicated.

Additionally, not all of the crates are on crates.io. I have no idea why not. So, I would need to supply “local” copies of them anyway. I decided to just git subtree add the avr-hal git tree.

(That seemed better than the approach taken by the avr-hal project’s cargo template, since that template involve a cargo dependency on a foreign git repository. Perhaps it would be possible to turn them into path dependencies, but given that I had evidence of file-location-sensitive behaviour, which I didn’t feel like I wanted to spend time investigating, using that seems like it would possibly have invited more trouble. Also, I don’t like package templates very much. They’re a form of clone-and-hack: you end up stuck with whatever bugs or oddities exist in the version of the template which was current when you started.)

Since I couldn’t get things to build outside avr-hal, I edited the example, within avr-hal, to refer to my (one) program.rs file outside avr-hal, with a #[path] instruction. That’s not pretty, but it worked.

I also had to write a nasty shell script to work around the lack of good support in my nailing-cargo privsep tool for builds where cargo must be invoked in a deep subdirectory, and/or Cargo.lock isn’t where it expects, and/or the target directory containing build products is in a weird place. It also has to filter the output from cargo to adjust the pathnames in the error messages. Otherwise, running both cd A; cargo build and cd B; cargo build from a Makefile produces confusing sets of error messages, some of which contain filenames relative to A and some relative to B, making it impossible for my Emacs to reliably find the right file.

RIIR (Rewrite It In Rust)

Having got my build tooling sorted out I could go back to my actual program.

I translated the main program, and the simulator, from C to Rust, more or less line-by-line. I made the Rust version of the simulator produce the same output format as the C one. That let me check that the two programs had the same (simulated) behaviour. Which they did (after fixing a few glitches in the simulator log formatting).

Emboldened, I flashed the Rust version of my program to the DigiSpark. It worked right away!

RIIR had caused the bug to vanish. Of course, to rewrite the program in Rust, and get it to compile, it was necessary to be careful about the types of all the various integers, so that’s not so surprising. Indeed, it was the point. I was then able to refactor the program to be a bit more natural and DRY, and improve some internal interfaces. Rust’s greater power, compared to C, made those cleanups easier, so making them worthwhile.

However, when doing real-world testing I found a weird problem: my timings were off. Measured, the real program was too fast by a factor of slightly more than 2. A bit of searching (and searching my memory) revealed the cause: I was using a board template for an Adafruit Trinket. The Trinket has a clock speed of 8MHz. But the DigiSpark runs at 16.5MHz. (This is discussed in a ticket against one of the C/C++ libraries supporting the ATTiny85 chip.)

The Arduino IDE had offered me a choice of clock speeds. I have no idea how that dropdown menu took effect; I suspect it was adding prelude code to adjust the clock prescaler. But my attempts to mess with the CPU clock prescaler register by hand at the start of my Rust program didn’t bear fruit.

So instead, I adopted a bodge: since my code has (for code structure reasons, amongst others) only one place where it dealt with the underlying hardware’s notion of time, I simply changed my delay function to adjust the passed-in delay values, compensating for the wrong clock speed.

There was probably a more principled way. For example I could have (re)based my work on either of the two unmerged open MRs which added proper support for the DigiSpark board, rather than abusing the Adafruit Trinket definition. But, having a nearly-working setup, and an explanation for the behaviour, I preferred the narrower fix to reopening any cans of worms.

An offer of help

As will be obvious from this posting, I’m not an expert in dev tools for embedded systems. Far from it. This area seems like quite a deep swamp, and I’m probably not the person to help drain it. (Frankly, much of the improvement work ought to be done, and paid for, by hardware vendors.)

But, as a full Member of the Debian Project, I have considerable gatekeeping authority there. I also have much experience of software packaging, build systems, and release management. If anyone wants to try to improve the situation with embedded tooling in Debian, and is willing to do the actual packaging work. I would be happy to advise, and to review and sponsor your contributions.

An obvious candidate: it seems to me that micronucleus could easily be in Debian. Possibly a DigiSpark board definition could be provided to go with the arduino package.

Unfortunately, IMO Debian’s Rust packaging tooling and workflows are very poor, and the first of my suggestions for improvement wasn’t well received. So if you need help with improving Rust packages in Debian, please talk to the Debian Rust Team yourself.


Embedded programming is still rather a mess and probably always will be.

Embedded build systems can be bizarre. Documentation is scant. You’re often expected to download “board support packages” full of mystery binaries, from the board vendor (or others).

Dev tooling is maddening, especially if aimed at novice programmers. You want version control? Hermetic tracking of your project’s build and install configuration? Actually to be told by the compiler when you write obvious bugs? You’re way off the beaten track.

As ever, Free Software is under-resourced and the maintainers are often busy, or (reasonably) have other things to do with their lives.

All is not lost

Rust can be a significantly better bet than C for embedded software:

The Rust compiler will catch a good proportion of programming errors, and an experienced Rust programmer can arrange (by suitable internal architecture) to catch nearly all of them. When writing for a chip in the middle of some circuit, where debugging involves staring an LED or a multimeter, that’s precisely what you want.

Rust embedded dev tooling was, in this case, considerably better. Still quite chaotic and strange, and less mature, perhaps. But: significantly fewer mystery downloads, and significantly less crazy deviations from the language’s normal build system. Overall, less bad software supply chain integrity.

The ATTiny85 chip, and the DigiSpark board, served my hardware needs very well. (More about the hardware aspects of this project in a future posting.)

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22 October, 2023 04:04PM