[PATCH v2 1/2] drm: Add GPU reset sysfs event

[Sharma, Shashank]

On 3/10/2022 4:24 PM, Rob Clark wrote:
> On Thu, Mar 10, 2022 at 1:55 AM Christian König
> <ckoenig.leichtzumerken at gmail.com> wrote:
>>
>>
>>
>> Am 09.03.22 um 19:12 schrieb Rob Clark:
>>> On Tue, Mar 8, 2022 at 11:40 PM Shashank Sharma
>>> <contactshashanksharma at gmail.com> wrote:
>>>> From: Shashank Sharma <shashank.sharma at amd.com>
>>>>
>>>> This patch adds a new sysfs event, which will indicate
>>>> the userland about a GPU reset, and can also provide
>>>> some information like:
>>>> - process ID of the process involved with the GPU reset
>>>> - process name of the involved process
>>>> - the GPU status info (using flags)
>>>>
>>>> This patch also introduces the first flag of the flags
>>>> bitmap, which can be appended as and when required.
>>> Why invent something new, rather than using the already existing devcoredump?
>>
>> Yeah, that's a really valid question.
>>
>>> I don't think we need (or should encourage/allow) something drm
>>> specific when there is already an existing solution used by both drm
>>> and non-drm drivers.  Userspace should not have to learn to support
>>> yet another mechanism to do the same thing.
>>
>> Question is how is userspace notified about new available core dumps?
> 
> I haven't looked into it too closely, as the CrOS userspace
> crash-reporter already had support for devcoredump, so it "just
> worked" out of the box[1].  I believe a udev event is what triggers
> the crash-reporter to go read the devcore dump out of sysfs.

I had a quick look at the devcoredump code, and it doesn't look like 
that is sending an event to the user, so we still need an event to 
indicate a GPU reset.

- Shashank

> 
> BR,
> -R
> 
> [1] One small change to allow-list the drm/msm devcore dumps was
> needed after a privacy review/audit of what is contained in the GPU
> devcored to ensure it does not contain any PII .. for CrOS on amd
> devices I'd be happy to walk whoever deals with amd CrOS devices
> through the process offline.
> 
>> Regards,
>> Christian.
>>
>>>
>>> BR,
>>> -R
>>