Re: [9fans] Drawterm GPU (was: Software philosophy)

[Bakul Shah <bakul@iitbombay.org>]

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The FreeBSD amdgpu.ko is over 3Mbytes of compiled code. Not counting the "firmware" that gets loaded on the GPU board. drm/amd/amdgpu has 200K+ lines of source code. drm/amd over 2M lines of code. Intel's i915 seems to be about 1/10th the amd size. AIUI, this is linux GPU driver code, more or less unchanged (FreeBSD has shim code to use it). How did the interface to an SIMD processor get so complicated?

> On Aug 22, 2021, at 6:44 AM, Paul Lalonde <paul.a.lalonde@gmail.com <mailto:paul.a.lalonde@gmail.com>> wrote:
> 
> I'd love to see  GPU support for Plan9.  This discussion falls right into my professional capacity.  I'll say that people generally *grossly* underestimate the complexity of a modern GPU and of its supporting software stack.  The GPU driver is effectively a second operating system with shared memory and DMA interfaces to the host.  Even bringing up a modern GPU for just compute tasks is a very large endeavour.
> 
> That being said, if you want real hardware support, the best place to start is currently AMD's open-source stack.  Ignoring the Vulkan bit, understanding their platform abstraction layer (PAL) and shader ISA (https://developer.amd.com/wp-content/resources/Vega_Shader_ISA_28July2017.pdf <https://developer.amd.com/wp-content/resources/Vega_Shader_ISA_28July2017.pdf>) is the base.  The lower hardware levels are reasonably well-described in linux's libdrm and its AMD support in amdgpu.
> 
> Opinions on how to bring this to Plan9?  I don't really have any - it's a huge pile of work with minimal benefit.  If you're looking for lightweight graphics, WebGL is a doable path, and almost certainly the right way to experiment with Plan9-like interfaces to graphics hardware.
> 
> Paul
> 
> 
> 
> On Sun, Aug 22, 2021 at 5:30 AM sirjofri <sirjofri+ml-9fans@sirjofri.de <mailto:sirjofri%2Bml-9fans@sirjofri.de>> wrote:
> 
> 22.08.2021 14:10:20 Stuart Morrow <morrow.stuart@gmail.com <mailto:morrow.stuart@gmail.com>>:
> > Also:
> >> people have discussed that for years
> >
> > They have?  I mean I might have seen occasionally someone vaguely
> > going "some sort of GPU support would be cool to have".  That isn't
> > discussion.
> 
> I've even heard of someone actually making GPU stuff work on plan 9. I've 
> only heard from their partner, who made a cute glenda thing on a piece of 
> cloth. I chatted with her a little and told her she should encourage her 
> partner for some discussion about this in our channels. It looked like 
> it's some academic work, but I don't know any details about it.
> 
> Worst case, someone already has a proper and good GPU implementation for 
> Plan 9 and nobody knows about it.
> 
> sirjofri
> 
> Btw if the said person reads this: it would be nice to learn some 
> details.
> 
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-- Bakul


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