Commen=
t # 8
on bug 10511=
3
from Maciej S. Szmigiero
(In reply to Jan Vesely from comment #7)
> (In reply to Maciej S. Szmigiero from comment #6)
> > There are really two issues at play here:
> > 1) If the LLVM-generated code cannot be run properly then it shou=
ld be simply
> > rejected by whatever is actually in charge of submitting it to th=
e GPU (I
> > guess
> > this would be Mesa?).
> > This way an application will know it cannot use OpenCL for comput=
ation, at
> > least
> > not with this compute kernel.
> >=20
> > Instead, it currently looks like many of these test run but give =
incorrect
> > results, which is obviously rather bad.
>=20
> Do you have an example of this? clover should return OUT_OF_RESOURCES =
error
> when the compute state creation fails (like in the presence of code
> relocations).
> It does not change the content of the buffer, so it will return whatev=
er was
> stored in the buffer on creation.
Aren't program@execute@calls-struct and program@execute@tai=
l-calls tests
from comment 4 examples of this=
behavior?
These seem to run but return wrong results, or am I not parsing the piglit
test results correctly?
> > 2) Some (previous) Mesa + LLVM versions gen=
erate a command stream that
> > crashes the GPU and, as far as I can remember, sometimes even loc=
kup the
> > whole machine.
> >=20
> > It should not be possible to crash the GPU, regardless how incorr=
ect a
> > command stream that userspace sends to it is - because otherwise =
it is
> > possible for
> > an unprivileged user with GPU access to DoS the machine.
>=20
> This is a separate issue. GPU hangs are generally addressed via gpu re=
set
> which should be enabled for gfx8/9 GPUs in recent amdgpu.ko [0]
>=20
> [0] https:=
//patchwork.freedesktop.org/patch/257994/
This would explain why "amdgpu" seemed to not even attempt to res=
et the GPU
after a crash.
However, I think I've got at least one lockup when testing this issue half a
year ago on "radeon" driver ("amdgpu" is still marked a=
s experimental for SI
parts).
If I am able to reproduce it in the future I will report it then.