[Mesa-dev] [PATCH v2 3/3] i965: enable INTEL_blackhole_render

[Kenneth Graunke]

On Friday, April 6, 2018 7:31:41 AM PDT Lionel Landwerlin wrote:
> v2: condition the extension on context isolation support from the
>     kernel (Chris)
> 
> v3: (Lionel)
> 
>     The initial version of this change used a feature of the Gen7+
>     command parser to turn the primitive instructions into no-ops.
>     Unfortunately this doesn't play well with how we're using the
>     hardware outside of the user submitted commands. For example
>     resolves are implicit operations which should not be turned into
>     no-ops as part of the previously submitted commands (before
>     blackhole_render is enabled) might not be disabled. For example
>     this sequence :
> 
>        glClear();
>        glEnable(GL_BLACKHOLE_RENDER_INTEL);
>        glDrawArrays(...);
>        glReadPixels(...);
>        glDisable(GL_BLACKHOLE_RENDER_INTEL);
> 
>     While clear has been emitted outside the blackhole render, it
>     should still be resolved properly in the read pixels. Hence we
>     need to be more selective and only disable user submitted
>     commands.
> 
>     This v3 manually turns primitives into MI_NOOP if blackhole render
>     is enabled. This lets us enable this feature on any platform.
> 
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_compute.c      | 46 +++++++++++---------
>  src/mesa/drivers/dri/i965/brw_defines.h      |  8 +++-
>  src/mesa/drivers/dri/i965/brw_draw.c         | 20 ++++++---
>  src/mesa/drivers/dri/i965/intel_extensions.c |  1 +
>  4 files changed, 49 insertions(+), 26 deletions(-)

Another potential issue with this patch...it doesn't stub out BLORP
operations.  Maybe that's intentional?  Should BlitFramebuffer,
CopyTexSubImage, CopyImageSubData, and so on do anything?  I had
originally thought you might need handling for Clear here, but you
do that explicitly in patch 2.  Wasn't sure about the others...
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