Quoting Tvrtko Ursulin (2018-02-21 13:42:29)
>
> On 21/02/2018 13:35, Tvrtko Ursulin wrote:
> >
> > On 21/02/2018 13:07, Chris Wilson wrote:
> >> Quoting Tvrtko Ursulin (2018-02-21 12:55:17)
> >>>
> >>> On 21/02/2018 12:53, Tvrtko Ursulin wrote:
> >>>>
> >>>> On 21/02/2018 12:17, 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.
> >>>>>
> >>>>> v2: When in doubt, shout!
> >>>>>
> >>>>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >>>>> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> >>>>> ---
> >>>>> 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..b9b86079 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) {
> >>>>> - if (ring & (3 << 13) && !gem_has_bsd2(fd))
> >>>>> + if (!(ring & (3 << 13)) ^ !gem_has_bsd2(fd))
> >>>>> return false;
> >>>>> }
>
> For preserving time and sanity:
>
> bool is_bsd = (ring & 0xf) == I915_EXEC_BSD;
& 63
Just to remind you how broken it all is.
> bool implicit_bsd = !(ring & (3 << 13));
> bool supports_explicit_bsd = gem_has_bsd2(fd);
>
> if (is_bsd) {
> if (implicit_bsd && supports_explicit_bsd)
> return false;
> else if (!implicit_bsd && !supports_explicit_bsd)
> return false;
> }
>
class/instance to the rescue. :)
-Chris
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