• tested a laptop that had a defective battery with a known good one (the problem was indeed with the battery :D)
• renewed his expiring OpenPGP key
• worked on removing trapperkeeper-scheduler-clojure from the DebCI reject_list
• helped anarcat with packaging sigal
• managed to feed most of the people present :)

• worked with lavamind to upload new upstream release of smokeping

• migrated from lxd to incus on his servers
• helped anarcat with flashing his AirGradient

• submitted a bug report on r-cran-rserve (promptly fixed/uploaded by maintainer!)
• reviewed and uploaded smokeping
• bug triaged the facter package
• worked on puppet-agent new upstream version 8.4.0

• updated puppet-strings from 2.9.0 to 4.2.1
• reported upstream test failures on puppet-strings with recent versions of mdl

• drafted a call & request for funding for the Vanier College FLOSS Club hardware marathon at Eastern Bloc
• worked on an application to conduct research at Vanier College on Debian usability
• babysitted :-)

• worked on his AirGradient
• debugged the WiFi and VPN setup on his new laptop

• worked on packaging sigal
• worked on flashing his AirGradient boards
• rewrote a Prometheus exporter for Airgradient devices
• brought over a car full of old computer gear to donate

• Orange line (top10)
• Green line (top10)
• Blue line
• Yellow line
• Global Top 10

• The subway map displayed on this page, the original dataset and my modified dataset are licenced under CCO 1.0: they are in the public domain.
• The R code I wrote is licensed under the GPLv3+. It's pretty much the same code as last year. I tweaked last's year converter script and although I had to clean some of the data by hand, it worked pretty well.

• March 8th: Godspeed You! Black Emperor
• April 11th: Alexandra Str liski
• April 12th: Bikini Kill
• April 21th: Brigada Flores Magon, Union Thugs
• April 28th: Komintern Sect, The Outcasts, Violent Way, Ultra Razzia, Over the Hill
• May 3rd: First Fragment
• May 12th: Rhapsody of Fire, Wind Rose
• May 13th: Aeternam
• June 2nd: Mortier, La Gachette
• June 17th: Ultra Razzia, Total Nada, BLEMISH
• June 30th: Avishai Cohen Trio
• July 9th: Richard Galliano
• August 18th: Gojira, Mastodon, Lorna Shore
• September 14th: Jinjer
• September 22nd: CUIR, Salvaje Punk, Hysteric Polemix, Perestroika, Ultra Razzia, Ilusion, Over the Hill, Asbestos
• October 6th: Rancoeur, Street Code, Tenaz, Mortimer, Guernica, High Anxiety

Previous findings In 2006, the Flosspols survey searched to explain the role of gender in free/libre/open source software (F/LOSS) communities because an earlier [study] revealed a significant discrepancy in the proportion of men to women. It showed that just about 1.5% of F/LOSS community members were female at that time, compared with 28% in proprietary software (which is also a low number). Their key findings were, to name just a few:

• that F/LOSS rewards the producing code rather than the producing software. It thereby puts most emphasis on a particular skill set. Other activities such as interface design or documentation are understood as less technical and therefore less prestigious.
• The reliance on long hours of intensive computing in writing successful code means that men, who in general assume that time outside of waged labour is theirs , are freer to participate than women, who normally still assume a disproportionate amount of domestic responsibilities. Female F/LOSS participants, however, seem to be able to allocate a disproportionate larger share of their leisure time for their F/LOSS activities. This gives an indication that women who are not able to spend as much time on voluntary activities have difficulties to integrate into the community.

We also know from the 2016 Debian survey, published in 2021, that a majority of Debian contributors are employed, rather than being contractors, and rather than being students. Also, 95.5% of respondents to that study were men between the ages of 30 and 49, highly educated, with the largest groups coming from Germany, France, USA, and the UK. The study found that only 20% of the respondents were being paid to work on Debian. Half of these 20% estimate that the amount of work on Debian they are being paid for corresponds to less than 20% of the work they do there. On the other side, there are 14% of those who are being paid for Debian work who declared that 80-100% of the work they do in Debian is remunerated.

So, if a majority of people is not paid, why do they work on F/LOSS? Or: What are the incentives of free software? In 2021, Louis-Philippe V ronneau aka Pollo, who is not only a Debian Developer but also an economist, published his thesis What are the incentive structures of free software (The actual thesis was written in French). One very interesting finding Pollo pointed out is this one:

Indeed, while we have proven that there is a strong and significative correlation between the income and the participation in a free/libre software project, it is not possible for us to pronounce ourselves about the causality of this link.

In the French original text:

En effet, si nous avons prouv qu il existe une corr lation forte et significative entre le salaire et la participation un projet libre, il ne nous est pas possible de nous prononcer sur la causalit de ce lien.

Said differently, it is certain that there is a relationship between income and F/LOSS contribution, but it s unclear whether working on free/libre software ultimately helps finding a well paid job, or if having a well paid job is the cause enabling work on free/libre software. I would like to scratch this question a bit further, mostly relying on my own observations, experiences, and discussions with F/LOSS contributors.

Volunteer work is unpaid work We often hear of hackathons, hack weeks, or hackfests. I ve been at some such events myself, Tails organized one, the IETF regularly organizes hackathons, and last week (June 2022!) I saw an invitation for a hack week with the Torproject. This type of event generally last several days. While the people who organize these events are being paid by the organizations they work for, participants on the other hand are generally joining on a volunteer basis. Who can we expect to show up at this type of event under these circumstances as participants? To answer this question, I collected some ideas:

• people who have an employer sponsoring their work
• people who have a funder/grant sponsoring their work
• people who have a high income and can take time off easily (in that regard, remember the Gender Pay Gap, women often earn less for the same work than men)
• people who rely on family wealth (living off an inheritance, living on rights payments from a famous grandparent - I m not making these situations up, there are actual people in such financially favorable situations )
• people who don t need much money because they don t have to pay rent or pay low rent (besides house owners that category includes people who live in squats or have social welfare paying for their rent, people who live with parents or caretakers)
• people who don t need to do care work (for children, elderly family members, pets. Remember that most care work is still done by women.)
• students who have financial support or are in a situation in which they do not yet need to generate a lot of income
• people who otherwise have free time at their disposal

So, who, in your opinion, fits these unwritten requirements? Looking at this list, it s pretty clear to me why we d mostly find white men from the Global North, generally with higher education in hackathons and F/LOSS development. ( Great, they re a culture fit! ) Yes, there will also always be some people of marginalized groups who will attend such events because they expect to network, to find an internship, to find a better job in the future, or to add their participation to their curriculum. To me, this rings a bunch of alarm bells.

Low diversity in F/LOSS projects a mirror of the distribution of wealth I believe that the lack of diversity in F/LOSS is first of all a mirror of the distribution of wealth on a larger level. And by wealth I m referring to financial wealth as much as to social wealth in the sense of Bourdieu: Families of highly educated parents socially reproducing privilege by allowing their kids to attend better schools, supporting and guiding them in their choices of study and work, providing them with relations to internships acting as springboards into well paid jobs and so on. That said, we should ask ourselves as well:

Do F/LOSS projects exacerbate existing lines of oppression by relying on unpaid work? Let s look again at the causality question of Pollo s research (in my words):

It is unclear whether working on free/libre software ultimately helps finding a well paid job, or if having a well paid job is the cause enabling work on free/libre software.

Maybe we need to imagine this cause-effect relationship over time: as a student, without children and lots of free time, hopefully some money from the state or the family, people can spend time on F/LOSS, collect experience, earn recognition - and later find a well-paid job and make unpaid F/LOSS contributions into a hobby, cementing their status in the community, while at the same time generating a sense of well-being from working on the common good. This is a quite common scenario. As the Flosspols study revealed however, boys often get their own computer at the age of 14, while girls get one only at the age of 20. (These numbers might be slightly different now, and possibly many people don t own an actual laptop or desktop computer anymore, instead they own mobile devices which are not exactly inciting them to look behind the surface, take apart, learn, appropriate technology.) In any case, the above scenario does not allow for people who join F/LOSS later in life, eg. changing careers, to find their place. I believe that F/LOSS projects cannot expect to have more women, people of color, people from working class backgrounds, people from outside of Germany, France, USA, UK, Australia, and Canada on board as long as volunteer work is the status quo and waged labour an earned privilege.

Wait, are you criticizing all these wonderful people who sacrifice their free time to work towards common good? No, that s definitely not my intention, I m glad that F/LOSS exists, and the F/LOSS ecosystem has always represented a small utopia to me that is worth cherishing and nurturing. However, I think we still need to talk more about the lack of diversity, and investigate it further.

Paid internships are one key to countering lines of oppression Lots of projects, even Outreachy and GSoC, require one contribution to F/LOSS to be made prior to be able to apply for a paid internship. I do well understand the incentive of this, but it s quite a high entry barrier. In 2014/2015 I was able to have 3 months of work on Debian paid for via an Outreachy internship. I was extremely grateful for that opportunity because without this paid internship I would never have found the time to engage with the Debian and F/LOSS ecosystem in depth simply because I would have had to work on my usual day job; I have rent to pay, and a health insurance which is really not cheap. These programs are key because they help counter existing lines of oppression at a strategic point: they buy someone s time by providing them a small income. Back then, the internship was paid 5,500USD gross for 3 months, meaning after taxes and paying social/health insurance, I was left with roughly 1100 per month, really not much money for living decently in Western Europe, but enough to get started. By the way, to my knowledge, 4 women who did an Outreachy internship subsequently became Debian Developers. 3 other female Debian Developers are or were part of Outreachy on the organizer side. I think this shows that this program is a success that we don t celebrate enough!

Some types of work are never being paid Besides free work at hacking events, let me also underline that a lot of work in F/LOSS is not considered payable work (yes, that s an oxymoron!). Which F/LOSS project for example, has ever paid translators a decent fee? Which project has ever considered that doing the social glue work, often done by women in the projects, is work that should be paid for? Which F/LOSS projects pay the people who do their Debian packaging rather than relying on yet another already well-paid white man who can afford doing this work for free all the while holding up how great the F/LOSS ecosystem is? And how many people on opensourcedesign jobs are looking to get their logo or website done for free? (Isn t that heart icon appealing to your altruistic empathy?) In my experience even F/LOSS projects which are trying to do the right thing by paying everyone the same amount of money per hour run into issues when it turns out that not all hours are equal and that some types of work do not qualify for remuneration at all or that the rules for the clocking of work are not universally applied in the same way by everyone.

Not every interaction should have a monetary value, but Some of you want to keep working without being paid, because that feels a bit like communism within capitalism, it makes you feel good to contribute to the greater good while not having the system determine your value over money. I hear you. I ve been there (and sometimes still am). But as long as we live in this system, even though we didn t choose to and maybe even despise it - communism is not about working for free, it s about getting paid equally and adequately. We may not think about it while under the age of 40 or 45, but working without adequate financial compensation, even half of the time, will ultimately result in not being able to care for oneself when sick, when old. And while this may not be an issue for people who inherit wealth, or have an otherwise safe economical background, eg. an academic salary, it is a huge problem and barrier for many people coming out of the working or service classes. (Oh and please, don t repeat the neoliberal lie that everyone can achieve whatever they aim for, if they just tried hard enough. French research shows that (in France) one has only 30% chance to become a class defector , and change social class upwards. But I managed to get out and move up, so everyone can! - well, if you believe that I m afraid you might be experiencing survivor bias.)

Not all bodies are equally able We should also be aware that not all of us can work with the same amount of energy either. There is yet another category of people who are excluded by the expectation of volunteer work, either because the waged labour they do already eats all of their energy, or because their bodies are not disposed to do that much work, for example because of mental health issues - such as depression-, or because of physical disabilities.

When organizing events relying on volunteer work please think about these things. Yes, you can tell people that they should ask their employer to pay them for attending a hackathon - but, as I ve hopefully shown, that would not do it for many people, especially newcomers. Instead, you could propose a fund to make it possible that people who would not normally attend can attend. DebConf is a good example for having done this for many years.

Conclusively I would like to urge free software projects that have a budget and directly pay some people from it to map where they rely on volunteer work and how this hurts diversity in their project. How do you or your project exacerbate pre-existing lines of oppression by granting or not granting monetary value to certain types of work? What is it that you take for granted? As always, I m curious about your feedback!

Worth a read These ideas are far from being new. Ashe Dryden s well-researched post The ethics of unpaid labor and the OSS community dates back to 2013 and is as important as it was ten years ago.

• Kienan & Gabriel worked on the libinfluxdb-http-perl package (now in Sid!), which is needed for smokeping.
• J r me worked on updating JRuby to the latest upstream version.
• I failed to update monitoring-plugins-systemd to the latest upstream version. It seems the entire test suite has been re-written and I couldn't make it work in sbuild...
• Tiago and Tassia worked on the Debian Contributors website. More specifically, they added a DSA domains data source and created a scheduler on dcf.debian.net to make daily updates on the data sources in the dc-sources repository.
• Michael worked on the 2024 NorthSec badge.
• Gerard worked on debugging his broken AirGradient board.

• I triaged and closed a bunch of bug reports and started packaging labwc, a Wayland compositor heavily inspired by Openbox.
• J r me did some work on Clojure libraries that broke when Java 21 became supported in Sid.
• Gabriel worked on the libinfluxdb-http-perl library.
• Tiago and Tassia continued their work on the new DC Sources project and Tiago applied for a debian.net VM for this service.

• Marius Gripsgard (mariogrip)
• Mohammed Bilal (rmb)
• Lukas M rdian (slyon)
• Robin Gustafsson (rgson)
• David da Silva Polverari (polverari)
• Emmanuel Arias (eamanu)

• Aymeric Agon-Rambosson
• Blair Noctis
• Lena Voytek
• Philippe Coval
• John Scott

• 6 different pages for the supported weather data¹, accessible via the key0 button
• Alerting² on the PM2.5 page when the defined threshold has been crossed
• Automatic screen blanking after a defined amount of time to save the OLED screen from burn-in
• Manual screen blanking using the key1 button

• MicroPython is close enough to regular Python that I don't mind it. The standard library is much smaller, but there are ways to work around that.
• The Raspberry Pi Pico W is a fantastic board. At around 10 CAD (~7 USD), it's much cheaper than anything Arduino offers, much more powerful than those boards and gives you the option of not having to code in some terrible and weird C variant. It also has a nice ecosystem of compatible modules and hats.
• Displays, even if they advertise being "batteries included", often are not. I had the bad surprise of discovering the MicroPython driver for the Waveshare Pico OLED 1.3 was pretty bad and lacked a ton of features compared to their C code driver. Thankfully, I was lucky enough that the OLED panel it uses (the SH1107) is common enough for folks to have written their own drivers.
• thonny, a Python IDE, is probably the best tool to transfer files to the Raspberry Pico and to debug code, as it provides a file manager and a shell³. I'm a little annoyed by it not being vim, but I got used to its quirks fairly quickly.

• Now that Debian Bookworm has been released, we updated our ansible repository to work with Debian Bookworm. This encountered some issues, but nothing earth-shattering, and almost all of them are handled. The one thing that is still outstanding is that jibri requires OpenJDK 11, which is no longer in bookworm; a solution for that will need to be found in the longer term, but as jibri is only needed for online conferences, it is not quite as urgent (Stefano, Louis-Philippe).
• In past years, we used open "opsis" hardware to do screen grabbing. While these work, upstream development has stalled, and their intended functionality is also somewhat more limited than we would like. As such, we experimented with a USB-based HDMI capture device, and after playing with it for some time, decided that it is a good option and that we would like to switch to it. Support for the specific capture device that we played with has now also been added to all the relevant places. (Stefano, Carl)
• Another open tool that we have been using is voctomix, a software video mixer. Its upstream development has also stalled somewhat . While we managed to make it work correctly on Bookworm, we decided that to ensure long-term viability for the team, it would be preferable if we had an alternative. As such, we quickly investigated Nageru, Sesse's software video mixer, and decided that it can everything we need (and, probably, more). As such, we worked on implementing a user interface theme that would work with our specific requirements. Work on this is still ongoing, and we may decide that we are not ready yet for the switch by the time DebConf23 comes along, but we do believe that the switch is at least feasible. While working on the theme, we found a bug which Sesse quickly fixed for us after a short amount of remote debugging, so, thanks for that! (Stefano, Nicolas, Sesse)
• Our current streaming architecture uses HLS, which requires MPEG-4-based codecs. While fully functional, MPEG-4 is not the most modern of codecs anymore, not to mention the fact that it is somewhat patent-encumbered (even though some of these patents are expired by now). As such, we investigated switching to the AV1 codec for live streaming. Our ansible repository has been updated to support live streaming using that codec; the post-event transcoding part will follow soon enough. Special thanks, again, to Sesse, for pointing out a few months ago on Planet Debian that this is, in fact, possible to do. (Wouter)
• Apart from these big-ticket items, we also worked on various small maintenance things: upgrading, fixing, and reinstalling hosts and services, filing budget requests, and requesting role emails. (all of the team, really).

1. Plug both your Solo V2 and your OpenPGP smartcard
2. To get a list of the tokens scdaemon sees, run the following command: $ echo scd getinfo reader_list gpg-connect-agent --decode awk '/^D/ print $2 '
3. Identify your OpenPGP smartcard. For example, my Nitrokey Start is listed as 20A0:4211:FSIJ-1.2.15-43211613:0
4. Create a file in ~/.gnupg/scdaemon.conf with the following line reader-port $YOUR_TOKEN_ID. For example, in my case I have: reader-port 20A0:4211:FSIJ-1.2.15-43211613:0
5. Reload scdaemon: $ gpgconf --reload scdaemon

# when asked, press enter to confirm default settings
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs   sh

rustup target add x86_64-unknown-none

cargo new hack-the-planet
cd hack-the-planet

[package]
name = "hack-the-planet"
version = "0.1.0"
edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]

rm src/main.rs
touch src/main.rs

$ cargo build --release --target x86_64-unknown-none
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
error[E0463]: can't find crate for  std 
   
  = note: the  x86_64-unknown-none  target may not support the standard library
  = note:  std  is required by  hack_the_planet  because it does not declare  #![no_std] 
error[E0601]:  main  function not found in crate  hack_the_planet 
   
  = note: consider adding a  main  function to  src/main.rs 
Some errors have detailed explanations: E0463, E0601.
For more information about an error, try  rustc --explain E0463 .
error: could not compile  hack-the-planet  due to 2 previous errors

#![no_std]

$ cargo build --release --target x86_64-unknown-none
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
error[E0601]:  main  function not found in crate  hack_the_planet 
 --> src/main.rs:1:11
   
1   #![no_std]
              ^ consider adding a  main  function to  src/main.rs 
For more information about this error, try  rustc --explain E0601 .
error: could not compile  hack-the-planet  due to previous error

#![no_std]
#![no_main]

$ cargo build
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
error:  #[panic_handler]  function required, but not found
error: language item required, but not found:  eh_personality 
   
  = note: this can occur when a binary crate with  #![no_std]  is compiled for a target where  eh_personality  is defined in the standard library
  = help: you may be able to compile for a target that doesn't need  eh_personality , specify a target with  --target  or in  .cargo/config 
error: could not compile  hack-the-planet  due to 2 previous errors

#![no_std]
#![no_main]
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    loop  
 

$ cargo build --release --target x86_64-unknown-none
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
    Finished release [optimized] target(s) in 0.16s

$ target/x86_64-unknown-none/release/hack-the-planet
Segmentation fault (core dumped)

$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64

Making a basic program and executing it Ok let s try to make a valid program that basically just cleanly exits. First let s try to add some cpu instructions and verify they re indeed getting executed. Lemme introduce, the INT 3 instruction in x86_64 assembly. In binary it s also known as the 0xCC opcode. It crashes our program in a slightly different way, so if the error message changes, we know it worked. The other tutorials use a #[naked] function for the entry point, but since this feature isn t stabilized at the time of writing we re going to use the global_asm! macro. Also don t worry, I m not going to introduce every assembly instruction individually. Our program now looks like this:

#![no_std]
#![no_main]
use core::arch::global_asm;
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    loop  
 
global_asm!  
    ".global _start",
    "_start:",
    "int 3"
 

Running the build again (ok basically from now on the build is always going to be expected to work unless I say otherwise):

$ cargo build --release --target x86_64-unknown-none
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
    Finished release [optimized] target(s) in 0.11s

Let s try to disassemble the binary again:

$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64
Disassembly of section .text:
0000000000001210 <_start>:
    1210:	cc                   	int3

And sure enough, there s a cc instruction that was identified as int3. Let s try to run this:

$ target/x86_64-unknown-none/release/hack-the-planet
Trace/breakpoint trap (core dumped)

The error message of the crash is now slightly different because it s hitting our breakpoint cpu instruction. Funfact btw, if you run this in strace you can see this isn t making any system calls (aka not talking to the kernel at all, it just crashes):

$ strace -f ./hack-the-planet
execve("./hack-the-planet", ["./hack-the-planet"], 0x74f12430d1d8 /* 39 vars */) = 0
--- SIGTRAP  si_signo=SIGTRAP, si_code=SI_KERNEL, si_addr=NULL  ---
+++ killed by SIGTRAP (core dumped) +++
[1]    2796457 trace trap (core dumped)  strace -f ./hack-the-planet

Let s try to make a program that does a clean shutdown. To do this we inform the kernel with a system call that we may like to exit. We can get more info on this with man 2 exit and it defines exit like this:

[[noreturn]] void _exit(int status);

On Linux this syscall is actually called _exit and exit is implemented as a libc function, but we don t care about any of that today, it s going to do the job just fine. Also note how it takes a single argument of type int. In C-speak this means signed 32 bit , i32 in Rust. Next we need to figure out the syscall number of this syscall. These numbers are cpu architecture specific for some reason (idk, idc). We re looking these numbers up with ripgrep in /usr/include/asm/:

$ rg __NR_exit /usr/include/asm
/usr/include/asm/unistd_64.h
64:#define __NR_exit 60
235:#define __NR_exit_group 231
/usr/include/asm/unistd_x32.h
53:#define __NR_exit (__X32_SYSCALL_BIT + 60)
206:#define __NR_exit_group (__X32_SYSCALL_BIT + 231)
/usr/include/asm/unistd_32.h
5:#define __NR_exit 1
253:#define __NR_exit_group 252

Since we re on x86_64 the correct value is the one in unistd_64.h, 60. Also, on x86_64 the syscall number goes into the rax cpu register, the status argument goes in the rdi register. The return value of the syscall is going to be placed in the rax register after the syscall is done, but for exit the execution is never given back to us. Let s try to write 60 into the rax register and 69 into the rdi register. To copy into registers we re going to use the mov destination, source instruction to copy from source to destination. With these registers setup we can use the syscall cpu instruction to hand execution over to the kernel. Don t worry, there s only one more assembly instruction coming and for everything else we re going to use Rust. Our code now looks like this:

#![no_std]
#![no_main]
use core::arch::global_asm;
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    loop  
 
global_asm!  
    ".global _start",
    "_start:",
    "mov rax, 60",
    "mov rdi, 69",
    "syscall"
 

Build the binary, run it and print the exit code:

$ cargo build --release --target x86_64-unknown-none
$ target/x86_64-unknown-none/release/hack-the-planet; echo $?
69

Nice. Rust is quite literally putting these cpu instructions into the binary for us, nothing else.

$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64
Disassembly of section .text:
0000000000001210 <_start>:
    1210:	48 c7 c0 3c 00 00 00 	mov    $0x3c,%rax
    1217:	48 c7 c7 45 00 00 00 	mov    $0x45,%rdi
    121e:	0f 05                	syscall

Running this with strace shows the program does exactly one thing.

$ strace -f ./hack-the-planet
execve("./hack-the-planet", ["./hack-the-planet"], 0x70699fe8c908 /* 39 vars */) = 0
exit(69)                                = ?
+++ exited with 69 +++

Writing Rust Ok but even though cpu instructions can be fun at times, I d rather not deal with them most of the time (this might strike you as odd, considering this blog post). Instead let s try to define a function in Rust and call into that instead. We re going to define this function as unsafe (btw none of this is taking advantage of the safety guarantees by Rust in case it wasn t obvious. This tutorial is mostly going to stick to unsafe Rust, but for bigger projects you can attempt to reduce your usage of unsafe to opt back into normal safe Rust), it also declares the function with #[no_mangle] so the function name is preserved as main and we can call it from our global_asm entry point. Lastely, when our program is started it s going to get the stack address passed in one of the cpu registers, this value is expected to be passed to our function as an argument. Our function declares ! as return type, which means it never returns:

#[no_mangle]
unsafe fn main(_stack_top: *const u8) -> !  
    // TODO: this is missing
 

This won t compile yet, we need to add our assembly for the exit syscall back in.

#[no_mangle]
unsafe fn main(_stack_top: *const u8) -> !  
    asm!(
        "syscall",
        in("rax") 60,
        in("rdi") 0,
        options(noreturn)
    );
 

This time we re using the asm! macro, this is a slightly more declarative approach. We want to run the syscall cpu instruction with 60 in the rax register, and this time we want the rdi register to be zero, to indicate a successful exit. We also use options(noreturn) so Rust knows it should assume execution does not resume after this assembly is executed (the Linux kernel guarantees this). We modify our global_asm! entrypoint to call our new main function, and to copy the stack address from rsp into the register for the first argument rdi because it would otherwise get lost forever:

global_asm!  
    ".global _start",
    "_start:",
    "mov rdi, rsp",
    "call main"
 

Our full program now looks like this:

#![no_std]
#![no_main]
use core::arch::asm;
use core::arch::global_asm;
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    loop  
 
global_asm!  
    ".global _start",
    "_start:",
    "mov rdi, rsp",
    "call main"
 
#[no_mangle]
unsafe fn main(_stack_top: *const u8) -> !  
    asm!(
        "syscall",
        in("rax") 60,
        in("rdi") 0,
        options(noreturn)
    );
 

After building and disassembling this the Rust compiler is slowly starting to do work for us:

$ cargo build --release --target x86_64-unknown-none
$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64
Disassembly of section .text:
0000000000001210 <_start>:
    1210:	48 89 e7             	mov    %rsp,%rdi
    1213:	e8 08 00 00 00       	call   1220 <main>
    1218:	cc                   	int3
    1219:	cc                   	int3
    121a:	cc                   	int3
    121b:	cc                   	int3
    121c:	cc                   	int3
    121d:	cc                   	int3
    121e:	cc                   	int3
    121f:	cc                   	int3
0000000000001220 <main>:
    1220:	50                   	push   %rax
    1221:	b8 3c 00 00 00       	mov    $0x3c,%eax
    1226:	31 ff                	xor    %edi,%edi
    1228:	0f 05                	syscall
    122a:	0f 0b                	ud2

The mov and syscall instructions are still the same, but it noticed it can XOR the rdi register with itself to set it to zero. It s using x86 assembly language (the 32 bit variant of x86_64, that also happens to work on x86_64) to do so, that s why the register is refered to as edi in the disassembly. You can also see it s inserting a bunch of 0xCC instructions (for alignment) and Rust puts the opcodes 0x0F 0x0B at the end of the function to force an invalid opcode exception so the program is guaranteed to crash in case the exit syscall doesn t do it. This code still executes as expected:

$ strace -f ./hack-the-planet
execve("./hack-the-planet", ["./hack-the-planet"], 0x72dae7e5dc08 /* 39 vars */) = 0
exit(0)                                 = ?
+++ exited with 0 +++

Adding functions Ok we re getting closer but we aren t quite there yet. Let s try to write an exit function for our assembly that we can then call like a normal function. Remember that it takes a signed 32 bit integer that s supposed to go into rdi.

unsafe fn exit(status: i32) -> !  
    asm!(
        "syscall",
        in("rax") 60,
        in("rdi") status,
        options(noreturn)
    );
 

Actually, since this function doesn t take any raw pointers and any i32 is valid for this syscall we re going to remove the unsafe marker of this function. When doing this we still need to use unsafe within the function for our inline assembly.

fn exit(status: i32) -> !  
    unsafe  
        asm!(
            "syscall",
            in("rax") 60,
            in("rdi") status,
            options(noreturn)
        );
     
 

Let s call this function from our main, and also remove the infinity loop of the panic handler with a call to exit(1):

#![no_std]
#![no_main]
use core::arch::asm;
use core::arch::global_asm;
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    exit(1);
 
global_asm!  
    ".global _start",
    "_start:",
    "mov rdi, rsp",
    "call main"
 
fn exit(status: i32) -> !  
    unsafe  
        asm!(
            "syscall",
            in("rax") 60,
            in("rdi") status,
            options(noreturn)
        );
     
 
#[no_mangle]
unsafe fn main(_stack_top: *const u8) -> !  
    exit(0);
 

Running this still works, but interestingly the generated assembly didn t change at all:

$ cargo build --release --target x86_64-unknown-none
$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64
Disassembly of section .text:
0000000000001210 <_start>:
    1210:	48 89 e7             	mov    %rsp,%rdi
    1213:	e8 08 00 00 00       	call   1220 <main>
    1218:	cc                   	int3
    1219:	cc                   	int3
    121a:	cc                   	int3
    121b:	cc                   	int3
    121c:	cc                   	int3
    121d:	cc                   	int3
    121e:	cc                   	int3
    121f:	cc                   	int3
0000000000001220 <main>:
    1220:	50                   	push   %rax
    1221:	b8 3c 00 00 00       	mov    $0x3c,%eax
    1226:	31 ff                	xor    %edi,%edi
    1228:	0f 05                	syscall
    122a:	0f 0b                	ud2

Rust noticed there s no need to make it a separate function at runtime and instead merged the instructions of the exit function directly into our main. It also noticed the 0 argument in exit(0) means rdi is supposed to be zero and uses the XOR optimization mentioned before. Since main is not calling any unsafe functions anymore we could mark it as safe too, but in the next few functions we re going to deal with file descriptors and raw pointers, so this is likely the only safe function we re going to write in this tutorial so let s just keep the unsafe marker.

Printing text Ok let s try to do a quick hello world, to do this we re going to call the write syscall. Looking it up with man 2 write:

ssize_t write(int fd, const void buf[.count], size_t count);

The write syscall takes 3 arguments and returns a signed size_t. In Rust this is called isize. In C size_t is an unsigned integer type that can hold any value of sizeof(...) for the given platform, ssize_t can only store half of that because it uses one of the bits to indicate an error has occured (the first s means signed, write returns -1 in case of an error). The arguments for write are:

• the file descriptor to write to. stdout is located on file descriptor 1.
• a pointer/address to some memory.
• the number of bytes that should be written, starting at the given address.

Let s also lookup the syscall number of write:

% rg __NR_write /usr/include/asm
/usr/include/asm/unistd_64.h
5:#define __NR_write 1
24:#define __NR_writev 20
/usr/include/asm/unistd_32.h
8:#define __NR_write 4
150:#define __NR_writev 146
/usr/include/asm/unistd_x32.h
5:#define __NR_write (__X32_SYSCALL_BIT + 1)
323:#define __NR_writev (__X32_SYSCALL_BIT + 516)

The value we re looking for is 1. Let s write our write function (heh).

unsafe fn write(fd: i32, buf: *const u8, count: usize) -> isize  
    let r0;
    asm!(
        "syscall",
        inlateout("rax") 1 => r0,
        in("rdi") fd,
        in("rsi") buf,
        in("rdx") count,
        lateout("rcx") _,
        lateout("r11") _,
        options(nostack, preserves_flags)
    );
    r0
 

Now that s a lot of stuff at once. Since this syscall is actually going to hand execution back to our program we need to let Rust know which cpu registers the syscall is writing to, so Rust doesn t attempt to use them to store data (that would be silently overwritten by the syscall). inlateout("raw") 1 => r0 means we re writing a value to the register and want the result back in variable r0. in("rdi") fd means we want to write the value of fd into the rdi register. lateout("rcx") _ means the Linux kernel may write to that register (so the previous value may get lost), but we don t want to store the value anywhere (the underscore acts as a dummy variable name). This doesn t compile just yet though

$ cargo build --release --target x86_64-unknown-none
   Compiling hack-the-planet v0.1.0 (/hack-the-planet)
error: incompatible types for asm inout argument
  --> src/main.rs:35:26
    
35           inlateout("rax") 1 => r0,
                              ^    ^^ type  isize 
                               
                              type  i32 
    
   = note: asm inout arguments must have the same type, unless they are both pointers or integers of the same size
error: could not compile  hack-the-planet  due to previous error

Rust has inferred the type of r0 is isize since that s what our function returns, but the type of the input value for the register was inferred to be i32. We re going to select a specific number type to fix this.

unsafe fn write(fd: i32, buf: *const u8, count: usize) -> isize  
    let r0;
    asm!(
        "syscall",
        inlateout("rax") 1isize => r0,
        in("rdi") fd,
        in("rsi") buf,
        in("rdx") count,
        lateout("rcx") _,
        lateout("r11") _,
        options(nostack, preserves_flags)
    );
    r0
 

We can now call our new write function like this:

write(1, b"Hello world\n".as_ptr(), 12);

We need to set the number of bytes we want to write explicitly because there s no concept of null-byte termination in the write system call, it s quite literally write the next X bytes, starting from this address . Our program now looks like this:

#![no_std]
#![no_main]
use core::arch::asm;
use core::arch::global_asm;
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_info: &PanicInfo) -> !  
    exit(1);
 
global_asm!  
    ".global _start",
    "_start:",
    "mov rdi, rsp",
    "call main"
 
fn exit(status: i32) -> !  
    unsafe  
        asm!(
            "syscall",
            in("rax") 60,
            in("rdi") status,
            options(noreturn)
        );
     
 
unsafe fn write(fd: i32, buf: *const u8, count: usize) -> isize  
    let r0;
    asm!(
        "syscall",
        inlateout("rax") 1isize => r0,
        in("rdi") fd,
        in("rsi") buf,
        in("rdx") count,
        lateout("rcx") _,
        lateout("r11") _,
        options(nostack, preserves_flags)
    );
    r0
 
#[no_mangle]
unsafe fn main(_stack_top: *const u8) -> !  
    write(1, b"Hello world\n".as_ptr(), 12);
    exit(0);
 

Let s try to build and disassemble it:

$ cargo build --release --target x86_64-unknown-none
$ objdump -d target/x86_64-unknown-none/release/hack-the-planet
target/x86_64-unknown-none/release/hack-the-planet:     file format elf64-x86-64
Disassembly of section .text:
0000000000001220 <_start>:
    1220:	48 89 e7             	mov    %rsp,%rdi
    1223:	e8 08 00 00 00       	call   1230 <main>
    1228:	cc                   	int3
    1229:	cc                   	int3
    122a:	cc                   	int3
    122b:	cc                   	int3
    122c:	cc                   	int3
    122d:	cc                   	int3
    122e:	cc                   	int3
    122f:	cc                   	int3
0000000000001230 <main>:
    1230:	50                   	push   %rax
    1231:	48 8d 35 d5 ef ff ff 	lea    -0x102b(%rip),%rsi        # 20d <_start-0x1013>
    1238:	b8 01 00 00 00       	mov    $0x1,%eax
    123d:	ba 0c 00 00 00       	mov    $0xc,%edx
    1242:	bf 01 00 00 00       	mov    $0x1,%edi
    1247:	0f 05                	syscall
    1249:	b8 3c 00 00 00       	mov    $0x3c,%eax
    124e:	31 ff                	xor    %edi,%edi
    1250:	0f 05                	syscall
    1252:	0f 0b                	ud2

This time there are 2 syscalls, first write, then exit. For write it s setting up the 3 arguments in our cpu registers (rdi, rsi, rdx). The lea instruction subtracts 0x102b from the rip register (the instruction pointer) and places the result in the rsi register. This is effectively saying an address relative to wherever this code was loaded into memory . The instruction pointer is going to point directly behind the opcodes of the lea instruction, so 0x1238 - 0x102b = 0x20d. This address is also pointed out in the disassembly as a comment. We don t see the string in our disassembly but we can convert our 0x20d hex to 525 in decimal and use dd to read 12 bytes from that offset, and sure enough:

$ dd bs=1 skip=525 count=12 if=target/x86_64-unknown-none/release/hack-the-planet
Hello world
12+0 records in
12+0 records out

Execute our binary with strace also shows the new write syscall (and the bytes that are being written mixed up in the output).

$ strace -f ./hack-the-planet
execve("./hack-the-planet", ["./hack-the-planet"], 0x74493abe64a8 /* 39 vars */) = 0
write(1, "Hello world\n", 12Hello world
)           = 12
exit(0)                                 = ?
+++ exited with 0 +++

After running strip on it to remove some symbols the binary is so small, if you open it in a text editor it fits on a screenshot:

• Orange line (top10)
• Green line (top10)
• Blue line
• Yellow line
• Global Top 10

• The subway map displayed on this page, the original dataset and my modified dataset are licenced under CCO 1.0: they are in the public domain.
• The R code I wrote is licensed under the GPLv3+. It's pretty much the same code as last year. I re-used last's year converter script and although I had to clean some of the data by hand, it worked pretty well.

• April 26th: Arch Enemy, Unto Others, Behemoth, Napalm Death
• September 16th: NOFX
• November 4th: Aeternam
• November 7th: Jordi Savall & Hesp rion XXI
• November 13th: VOLA
• November 19th: Vulgaires Machins, Anti-Flag
• November 26th: Soen
• December 12h: Oddisee
• December 16th: Jail, B ton Arm , Reckless Upstarts, Union Thugs, La Gachette

• tienne Mollier (emollier)
• Taihsiang Ho (tai271828)
• Athos Ribeiro (athos)
• Stuart Prescott (stuart)
• Louis-Philippe V ronneau (pollo)
• Ileana Dumitrescu (ildumi)
• James Valleroy (jvalleroy)
• Emmanuel Arias (eamanu)
• Kurt Kremitzki (kkremitzki)
• Mohammed Bilal (rmb)
• Stefano Rivera (tumbleweed)
• Jeroen Ploemen (jcfp)

• the addition of a "missing-cpython-extension" tag to flag packages that do not build CPython extensions for all the supported Python versions.
• fixing a false-positive in the "missing-prerequisite-for-pyproject-backend" tag.

• improving existing packages (for example, adding or fixing autopkgtests)
• triaging and fixing Python 3.11 bugs
• updating packages to the latest upstream release
• sponsoring uploads