[Intel-gfx] [PATCH 09/13] drm/i915: Extend I915_CONTEXT_PARAM_SSEU to support local ctx->engine[]

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-03-08 16:31:51)
> 
> On 08/03/2019 14:12, Chris Wilson wrote:
> > Allow the user to specify a local engine index (as opposed to
> > class:index) that they can use to refer to a preset engine inside the
> > ctx->engine[] array defined by an earlier I915_CONTEXT_PARAM_ENGINES.
> > This will be useful for setting SSEU parameters on virtual engines that
> > are local to the context and do not have a valid global class:instance
> > lookup.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > ---
> >   drivers/gpu/drm/i915/i915_gem_context.c | 24 ++++++++++++++++++++----
> >   include/uapi/drm/i915_drm.h             |  3 ++-
> >   2 files changed, 22 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> > index 86d9bea6f275..a581c01ffff1 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_context.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> > @@ -1313,6 +1313,7 @@ static int set_sseu(struct i915_gem_context *ctx,
> >       struct drm_i915_gem_context_param_sseu user_sseu;
> >       struct intel_engine_cs *engine;
> >       struct intel_sseu sseu;
> > +     unsigned long lookup;
> 
> Poor 32-bit builds. ;) And in lookup_user_engine as well.

It's an internal flags variable; not a direct part of the uABI. So it's
only use is to control lookup_user_engine() so limiting it to 32b
(natural register width) doesn't seem a like a concern for the
forseeable future? How many different ABI interfacing methods of looking
up an engine do you have planned?
-Chris