On Thu, Nov 26, 2015 at 12:34:34PM +0100, Daniel Vetter wrote:
> So there's 3 competing proposals for what wait_ioctl should do wrt
> -EIO:
>
> - return -EIO when the gpu is wedged. Not terribly useful for
> userspace since it might race with a hang and then there's no
> guarantee that a subsequent execbuf won't end up in an -EIO.
> Terminally wedge really can only be reliably signalled at execbuf
> time, and userspace needs to cope with that (or decide not to
> bother).
>
> - EIO for any obj that suffered from a reset. This means big internal
> reorginazation in the kernel since currently we track reset stats
> per-ctx and not on the obj. That's also what arb robustness wants.
> We could do this, but this feels like new ABI territory with the
> usual userspace requirements and high hurdles.
>
> - No -EIO at all. Consistent with set_domain_ioctl and simplest to
> implement. Which is what this patch does.
Since no one else is weighing into the ABI discussion, I'm happy with
losing EIO here. I thought it could be useful, but as no one is using or
seems likely to start using it, begone.
> We can always opt to change this later on if there's a real need.
>
> To make the test really exercise this do a full wedged gpu hang, to
> make sure -EIO doesn't leak out at all.
>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> ---
> tests/gem_eio.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/tests/gem_eio.c b/tests/gem_eio.c
> index a24c8f1c53b5..8345d1a7a429 100644
> --- a/tests/gem_eio.c
> +++ b/tests/gem_eio.c
> @@ -161,10 +161,14 @@ static void test_wait(int fd)
> {
> igt_hang_ring_t hang;
>
> + igt_require(i915_reset_control(false));
However, this is not required to test the ABI change above as the wait
itself will still hang, whether or not it wedges the GPU.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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