[Intel-gfx] [PATCH 02/13] drm/i915: Copy user requested buffers into the error state

[Matt Turner]

On Wed, Apr 12, 2017 at 2:43 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Wed, Mar 29, 2017 at 04:56:24PM +0100, Chris Wilson wrote:
>> Introduce a new execobject.flag (EXEC_OBJECT_CAPTURE) that userspace may
>> use to indicate that it wants the contents of this buffer preserved in
>> the error state (/sys/class/drm/cardN/error) following a GPU hang
>> involving this batch.
>>
>> Use this at your discretion, the contents of the error state. although
>> compressed, are allocated with GFP_ATOMIC (i.e. limited) and kept for all
>> eternity (until the error state is destroyed).
>>
>> Based on an earlier patch by Ben Widawsky <ben at bwidawsk.net>
>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Ben Widawsky <ben at bwidawsk.net>
>> Cc: Matt Turner <mattst88 at gmail.com>
>> Acked-by: Ben Widawsky <ben at bwidawsk.net>
>> Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>
> I believe Matt has userspace ready to make use of this flag and is happy
> with the current ABI. Matt, are we ready to commit ourselves to this
> interface?

Yes, from my end this interface works well.

I'm able to capture the instruction buffer, and recognize it by
matching the "user" buffer's address with that specified by
STATE_BASE_ADDRESS, and then disassemble the various programs
contained within by inspecting the kernel start pointers.

Thanks for handling the kernel side of things!