[Intel-gfx] [PATCH igt] lib: Skip aliased bsd ABI ring if bsd2 is available

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-21 12:25:55)
> 
> On 21/02/2018 11:21, Chris Wilson wrote:
> > How much do I want this uABI to rot away? Say "Never again!" to implicit
> > aliasing.
> > 
> > In the meantime, we do not need to perform duplicate work on bsd2
> > machines, as especially we do not know which engine bsd relates to.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > ---
> >   lib/ioctl_wrappers.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> > index 8748cfcf..868d68f7 100644
> > --- a/lib/ioctl_wrappers.c
> > +++ b/lib/ioctl_wrappers.c
> > @@ -1460,7 +1460,7 @@ bool gem_has_ring(int fd, unsigned ring)
> >   
> >       /* silly ABI, the kernel thinks everyone who has BSD also has BSD2 */
> >       if ((ring & ~(3<<13)) == I915_EXEC_BSD) {
> 
> What is this testing for? Why not just ring & i915_EXEC_RING_MASK == 
> I915_EXEC_BSD? It there are some other bits set it will behave strangely.

What other bits? :) (Note EXEC_RING_MASK has the wrong value in the
headers.)
-Chris