[PATCH 2/2] drm/amdgpu: Enable clear page functionality

[Christian König]

Am 12.12.23 um 00:32 schrieb Felix Kuehling:
>
> On 2023-12-11 04:50, Christian König wrote:
>> Am 08.12.23 um 20:53 schrieb Alex Deucher:
>>> [SNIP]
>>>> You also need a functionality which resets all cleared blocks to
>>>> uncleared after suspend/resume.
>>>>
>>>> No idea how to do this, maybe Alex knows of hand.
>>> Since the buffers are cleared on creation, is there actually 
>>> anything to do?
>>
>> Well exactly that's the problem, the buffers are no longer always 
>> cleared on creation with this patch.
>>
>> Instead we clear on free, track which areas are cleared and clear 
>> only the ones which aren't cleared yet on creation.
>
> The code I added for clearing-on-free a long time ago, does not clear 
> to 0, but to a non-0 poison value. That was meant to make it easier to 
> catch applications incorrectly relying on 0-initialized memory. Is 
> that being changed? I didn't see it in this patch series.

Yeah, Arun stumbled over that as well. Any objections that we fill with 
zeros instead or is that poison value something necessary for debugging?

Regards,
Christian.

>
> Regards,
>   Felix
>
>
>>
>> So some cases need special handling. E.g. when the engine is not 
>> initialized yet or suspend/resume.
>>
>> In theory after a suspend/resume cycle the VRAM is cleared to zeros, 
>> but in practice that's not always true.
>>
>> Christian.
>>
>>> Alex