Last week was kernel summit in Prague. Based on feedback from Linus and other people, kernel summit was a 2 day open technical forum along with a half-day “maintainer summit”. Open Source Summit Europe was also happening at the same time and I attended somethings there as well.
Darren Hart gave a talk about x86 platform drivers. Darren is the current maintainer of the x86 platform drivers. He gave a nice overview of what a platform driver actually is (a bunch of glue) and some history about how big or small drivers can be. One of the sticking points about drivers in general is that most hardware vendors only really focus on Windows and the driver philosophy there is different from Linux. This results in Linux needing to play catch-up and work around firmware that was only tested on Windows (see also the example of vendor “To be filled by O.E.M.”). Hardware vendors can make this easier by using standard interfaces and also open sourcing firmware, something the Fedora community cares deeply about.
Laurent Pinchart ran a session called “Bash the Kernel Maintainers”. This was designed to be a feedback session for attendees to express opinions about the kernel process. Most of the feedback was things I’ve heard before (and even expressed myself). Submitting patches as a new user is still intimidating. There was some discussion about making it easier for users to access the zeroday bot without having to submit something publicly. The topic of bots reminded me of some of the themes I heard when I was at maintainerati. The complete lack of consistency among maintainers was a big theme. There is no one rule about where to send a patch or when to ping a maintainer for a review or even how to get status about a patch. This is still one of my pet peeves as a full time kernel developer. Laurent took great notes and gave a readout at the kernel maintainer’s summit.
For the first day of kernel summit, Steven Rostedt and Mathieu Desnoyers talked about the tracing ABI. The kernel has a (reasonably) consistent rule that userspace is an ABI and you do not break userspace. This makes sense for things like traditionally compiled userspace programs and syscalls. The tracing infrastructure in tree has grown over the years which has made debugging much easier. If that tracing infrastructure gets exposed to userspace though, it might end up looking like an ABI, which means that if tracepoints get changed or removed tools that depend on it might break. The presenters argued that even if it is an ABI, tools developers were perfectly willing to recompile on each kernel version to match. Linus disagreed. LWN did a much more complete writeup of the topic.
Peter Robinson and Jim Perrin ran a BOF on the state of ARM on Fedora. This was mostly a brief status update (Fedora rocks) with time to ask questions. People were mostly interested in device support so there was some discussion and explanation about what is required to support these things in Fedora (reasonable mainline graphics support). Great session.
The kernel Outreachy interns each gave presentations on what they worked on. There were six different projects across the kernel, from documentation to IIO. I always enjoy hearing Outreachy interns talk about what they accomplished. For many of them, this was their first contribution to open source or even kernel programming. Outreachy is a fantastic program and it shows what can be accomplished with a supportive mentor.
Thorsten Leemhuis gave a presentation on kernel regression tracking. There had not been anyone keeping track of regressions in the kernel for years until Thorsten picked up the task earlier this year. It’s a very valuable but thankless job. Thorsten talked about some of the difficulties including getting people to actually send him regressions and how to keep track of what he did find. There was talk of creating a regressions@ mailing list which should hopefully make reporting easier. The topic of bugzilla came up once again and it sounded like there was agreement to improve the landing page to make bug reporting more easier. As a Fedora maintainer, regressions are near and dear to my heart so I plan on keeping an eye on this.
Konstantin Ryabitsev, a sysadmin for kernel.org, gave a presentation on security hygiene. The intended audience was kernel developers but everything applies to developers in general. PGP is still the most widely used mechanism out there and the kernel community relies on it for trust. Linus signs all releases as does Greg KH for the stable releases. There was some discussion about the trust in git pull requests and how much signing should actually be happening. Konstantin is a big promoter of hardware tokens for storing your subkeys. I have a yubikey but haven’t made much use of it (and apparently need to update my keys thanks to the latest flaw). I really enjoyed this talk mostly because the security suggestions were very practical, even if they did acknowledge that some problems like video conferencing were still insecure. I’ll be reimaging my laptop soon so I’ll hopefully be able to implement some of the suggestions.
The maintainer’s summit was a half-day even closer to what the kernel summit used to be. This was the first time the new format was used and overall it went well. There were only about 30 of us which made discussions much easier, especially on topics like regression tracking and maintainer bashing. All the discussion felt productive and I think we made useful progress. I expect LWN to have a more complete writeup in the near future.
Once again, a great conference in a great city. I love Prague.