[Intel-gfx] [PATCH igt v2] lib: Skip aliased bsd ABI ring if bsd2 is available
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Wed Feb 21 12:53:55 UTC 2018
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 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..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;
> }
If default BSD (1)
and no BSD2 -> 1 ^ 1 = 1 OK
and BSD2 -> 1 ^ 0 = 1 BAD
If explicit BSD (0)
and no BSD2 -> 0 ^ 1 = 1 BAD
has BSD2 -> 0 ^ 0 = 0 = BAD
Maybe I'm confused.. please simplify the statement? :)
Regards,
Tvrtko
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