[Intel-gfx] [RFC 0/2] Add Pooled EU support

[Chris Wilson]

On Sat, Jul 11, 2015 at 08:05:05PM +0100, Chris Wilson wrote:
> On Fri, Jul 10, 2015 at 06:35:18PM +0100, Arun Siluvery wrote:
> > These patches enabled Pooled EU support for BXT, they are implemented
> > by Armin Reese. I am sending these patches in its current form for comments.
> > 
> > These patches modify Golden batch to have a set of modification values
> > where we can change the commands based on Gen. The commands to enable
> > Pooled EU are inserted after MI_BATCH_BUFFER_END. If the given Gen
> > supports this feature, modification values are used to replace
> > MI_BATCH_BUFFER_END so we send commands to enable Pooled EU. These
> > commands need to be part of this batch because they are to be
> > initialized only once. Userspace will have option to query the
> > availability of this feature, those changes are not included in
> > this series.
> 
> Would it not just be simpler to execute 2 batches? First holding the
> basic and common state for the gen, the second using subgen. That we
> have a chunk of binary data is nasty, but at least we can point to the
> generator and be able to decipher it and recreate it as required. Doing
> binary patching on top, on that path lies madness.
> 
> What is the minimum instruction sequence required to be able to setup the
> default EU state? Is it small enough that carrying it as code in the
> kernel is viable (and readable)?
> 
> (That actually is critical here as currently we have to juggle multiple
> sources and look very carefully at what is being patched - I am not
> confident that we will not introduce mistakes in a week's time, let
> alone a year or two.)

The alternative is to just say that the patch table is also
autogenerated and for that to be simple and clear, and far more
documentated as it relies on a strict protocol.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre