[Intel-gfx] [igt-dev] [PATCH i-g-t] i915/gem_exec_fence: Use default-context for syncobj-timeline-wait

[Chris Wilson]

Quoting Lionel Landwerlin (2020-08-07 10:00:14)
> On 07/08/2020 11:45, Chris Wilson wrote:
> > syncobj-timeline-wait is only exercising waits on the syncobj along a
> > single timeline, for which it can use the universally available default
> > context, and so not try and fail to create a HW context on very old
> > platforms.
> >
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2308
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> 
> 
> Hm... I thought maybe we didn't get all the engines on the default context.

A fresh context, either the default for a new fd or from
gem_context_create(), only gets the default set of engines. The context
created here has a clone of the engines from the default context, which
we hope has been reconfigured already to have the set of all available
engines.

__for_each_physical_engine() works by querying the kernel and
reconfiguring the default context to suite. Fortunately that is run in a
fixture early on in gem_exec_fence, so by the time we get to the syncobj
group, we have all engines available.

Looks like we're good to iterate over them all :)
-Chris