Comment by doesnotmatter | Hacker News Reader

Comment by doesnotmatter | Hacker News Reader

Yea, that's cute, except that DRM can handle pretty much all of it. You can split hairs and complain about GPU scheduling which is inherently rather difficult because scheduling at the command queue level is problem very much alike the halting problem. The real issue isn't that we don't have the pieces we need but rather that we can't get all the players to agree on using the same ones. On Windows you have one entity (Microsoft) that can post WLK and unless you pass it you won't be certified and on GNU/Linux "a working driver" can be anything from "not catching on fire on boot" through "actually brings up display" to "oh, hey a textured triangle!". And I get it, everyone is frustrated because ultimately displaying a bunch of pixels, seems trivial, that is, until you mix in politics. You have NVIDIA, AMD, Intel and the community at large pulling all in different directions. With GNU/Linux graphics support having marginal effect on the bottom line there's little incentive to deal with it. And you'd still miss a controlling entity that could validate that "works on Linux" means anything but "compiles with some random kernel release".

Everyone who thinks that writing great graphics drivers can be a spare time activity is delusional. The fact that we have Android with Gralloc (which in comparison to DRM is, well, a joke), Ubuntu with Mir, others trying out Wayland and folks still stuck on X11 makes this all so much more complicated than it needs to be (and SteamOS is rather terrible in this regard too, which is a shame because Valve is trying to do the right thing with Vulkan but SteamOS is just not a well put together distro, at least right now). It's just not a driver model problem, it's the politics of it all. Outside of Google adopting DRM instead of Gralloc (or Gralloc getting all of the features on DRM and effectively becoming DRM and replacing it on the desktop) there's probably little chance of unifying all the drivers under one coherent umbrella.

I am sorry, sir. What is DRM? I only have Digital Rights Management flashing in into my memory, but I have no idea what you could mean with DRM. Apparently I've been able to ignore and live behind the moon, not knowing what DRM is, while using Linux mainly since 2003-2004.

I'm sad that there is no alternative to X that works with `legacy` graphic cards like mine (Radeon HD 4500). But to be honest I'm personally just concerned due to already mentioned security problems with Xorg.

A quick Google search found "Direct Rendering Manager": https://en.wikipedia.org/wiki/Direct_Rendering_Manager

Doesn't look like something you'd necessarily need to know about unless you were developing for the GPU on Linux.

Right, exactly. DRM is responsible for memory management, mode-setting, command submission and is capable of basically everything the original article asks for.

Unfortunately only the Free Software drivers fully support it, AMD is planning to switch its proprietary drivers to it (using their new amdgpu drm driver), and Nvidia doesn't use it on desktop at all but will likely at least implement the prime buffer sharing for optimus at some point.

There are various reasons for the current situation, e.g. Nvidia's OpenGL drivers are simply the best (on both Windows and GNU/Linux) so they had little reason to play nice with others, especially given that their mode-setting code was a bit better than what DRM used to do which is not the case anymore and hasn't been for a while, but companies need financial incentives to rewrite parts of their working codebases.

And even if you get all of the desktop GPUs on top of DRM then you'll still have Android and mobile GPUs. Certain mobile GPUs do work with DRM but that level of support is usually embarrassing and mostly done to be able to say "we did" rather than actually support any useful features in it which, is not completely unreasonable, because DRM doesn't buy you almost anything on Android right now so why bother.

Now, having said that, WDDM, particularly 2.0, does do some things that DRM can not. But DRM is not far behind (and capable of certain things wddm can not) and the real travesty is that not all GPU drivers on Linux (both GNU/Linux and Android) use it.

The perfect Linux (again, both GNU/Linux and Android) graphics stack will be: DRM kernel driver (not only command submission but memory management and mode-setting), Vulkan user-space driver (Vulkan will become basically what Gallium is right now which is a common layer on top of which we'll implement other, more friendly graphics apis) and Wayland.

DRM solves the multi-gpu sharing, synching, recovery, memory management, gives us a central place to manage security (although with GPUs that's a sort of an "interesting" topic which is a long discussion in itself) and do some rudimentary scheduling (which is, as mentioned previously, also "interesting"), Vulkan, as a side-effect of the fact that it's so tight and will come with a conformance framework, will make drivers a lot more predictable and stable and the Wayland faq explains why it's a neater choice than X11.

Unfortunately, while Google will adopt Vulkan, I doubt they'll have enough good will and reason to drop SurfaceFlinger and Gralloc in favor of DRM and Wayland. So we won't likely get to that stack anytime soon.

Calling it a political problem and not a technical problem doesn't make it less of a problem. Nor does dismissing it as "cute" offer much in the way of a solution.

Yes, except that I didn't do either one of those things. I was responding to the original article which is calling for a new driver model, which, as pointed out, is neither the problem or the solution.

Sorry, it was somewhat unclear what you were calling cute.

At least in software. I think politics can also be a technical problem.

People very smart, knowledgeable, wise, persistent, patient, cleaver, prudent etc. have been able to manage organizations with different concerns, priorities and goals.

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