Posts

On Rust, Linux, developers, maintainers

There's been a couple of mentions of Rust4Linux in the past week or two, one from Linus on the speed of engagement and one about Wedson departing the project due to non-technical concerns. This got me thinking about project phases and developer types. Archetypes: I will regret making an analogy, in an area I have no experience in, but let's give it a go with a road building analogy.   Let's sort developers into 3 rough categories. Let's preface by saying not all developers fit in a single category throughout their careers, and some developers can do different roles on different projects, or on the same project simultaneously. 1. Wayfinders/Mapmakers I want to go build a hotel somewhere but there exists no map or path. I need to travel through a bunch of mountains, valleys, rivers, weather, animals, friendly humans, antagonistic humans and some unknowns. I don't care deeply about them, I want to make a path to where I want to go. I hit a roadblock, I don't focus

anv: vulkan av1 decode status

 Vulkan Video AV1 decode has been released, and I had some partly working support on Intel ANV driver previously, but I let it lapse. The branch is currently [1]. It builds, but is totally untested, I'll get some time next week to plug in my DG2 and see if I can persuade it to decode some frames. Update: the current branch decodes one frame properly, reference frames need more work unfortunately. [1] https://gitlab.freedesktop.org/airlied/mesa/-/commits/anv-vulkan-video-decode-av1

radv: vulkan av1 video decode status

The Khronos Group announced VK_KHR_video_decode_av1 [1], this extension adds AV1 decoding to the Vulkan specification. There is a radv branch [2] and merge request [3]. I did some AV1 work on this in the past, but I need to take some time to see if it has made any progress since. I'll post an ANV update once I figure that out. This extension is one of the ones I've been wanting for a long time, since having royalty-free codec is something I can actually care about and ship, as opposed to the painful ones. I started working on a MESA extension for this a year or so ago with Lynne from the ffmpeg project and we made great progress with it. We submitted that to Khronos and it has gone through the committee process and been refined and validated amongst the hardware vendors. I'd like to say thanks to Charlie Turner and Igalia for taking over a lot of the porting to the Khronos extension and fixing up bugs that their CTS development brought up. This is a great feature of having

radv: vulkan video encode status

Vulkan 1.3.274 moves the Vulkan encode work out of BETA and moves h264 and h265 into KHR extensions. radv support for the Vulkan video encode extensions has been in progress for a while. The latest branch is at [1]. This branch has been updated for the new final headers. Updated: It passes all of h265 CTS now, but it is failing one h264 test. Initial ffmpeg support is [2]. [1] https://gitlab.freedesktop.org/airlied/mesa/-/tree/radv-vulkan-video-encode-h2645-spec-latest?ref_type=heads [2] https://github.com/cyanreg/FFmpeg/commits/vulkan/

nouveau GSP firmware support - current state

Linus has pulled the initial GSP firmware support for nouveau. This is just the first set of work to use the new GSP firmware and there are likely many challenges and improvements ahead. To get this working you need to install the firmware which hasn't landed in linux-firmware yet. For Fedora this copr has the firmware in the necessary places: https://copr.fedorainfracloud.org/coprs/airlied/nouveau-gsp/build/6593115/  Hopefully we can upstream that in next week or so. If you have an ADA based GPU then it should just try and work out of the box, if you have Turing or Ampere you currently need to pass nouveau.config=NvGspRm=1 on the kernel command line to attempt to use GSP. Going forward, I've got a few fixes and stabilization bits to land, which we will concentrate on for 6.7, then going forward we have to work out how to keep it up to date and support new hardware and how to add new features.

Talk about compute and community and where things are at.

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 Sriram invited me to the oneAPI meetup, and I felt I hadn't summed up the state of compute and community development in a while. Enjoy 45 minutes of opinions! https://www.youtube.com/watch?v=HzzLY5TdnZo

nvk: the kernel changes needed

The initial NVK (nouveau vulkan) experimental driver has been merged into mesa master[1], and although there's lots of work to be done before it's application ready, the main reason it was merged was because the initial kernel work needed was merged into drm-misc-next[2] and will then go to drm-next for the 6.6 merge window. (This work is separate from the GSP firmware enablement required for reclocking, that is a parallel development, needed to make nvk useable). Faith at Collabora will have a blog post about the Mesa side, this is more about the kernel journey. What was needed in the kernel? The nouveau kernel API was written 10 years or more ago, and was designed around OpenGL at the time. There were two major restrictions in the current uAPI that made it unsuitable for Vulkan. buffer objects (physical memory allocations) were allocated 1:1 with virtual memory allocations for a file descriptor. This meant the kernel managed the virtual address space. For proper Vulkan suppor