Re: [Intel-gfx] [PATCH v5 1/5] x86/quirks: Fix stolen detection with integrated + discrete GPU

[Lucas De Marchi <lucas.demarchi@intel.com>]

On Tue, Jan 18, 2022 at 02:01:45PM -0600, Bjorn Helgaas wrote:
>On Tue, Jan 18, 2022 at 07:37:29PM +0100, Borislav Petkov wrote:
>> On Tue, Jan 18, 2022 at 11:58:53AM -0600, Bjorn Helgaas wrote:
>> > I don't really care much one way or the other.  I think the simplest
>> > approach is to remove QFLAG_APPLY_ONCE from intel_graphics_quirks()
>> > and do nothing else, as I suggested here:
>> >
>> >   https://lore.kernel.org/r/20220113000805.GA295089@bhelgaas
>> >
>> > Unfortunately that didn't occur to me until I'd already suggested more
>> > complicated things that no longer seem worthwhile to me.
>> >
>> > The static variable might be ugly, but it does seem to be what
>> > intel_graphics_quirks() wants -- a "do this at most once per system
>> > but we don't know exactly which device" situation.
>>
>> I see.
>>
>> Yeah, keeping it solely inside intel_graphics_quirks() and maybe with a
>> comment ontop, why it is done, is simple. I guess if more quirks need
>> this once-thing people might have to consider a more sensible scheme - I
>> was just objecting to sprinkling those static vars everywhere.
>>
>> But your call. :)
>
>Haha :)  I was hoping not to touch it myself because I think this
>whole stolen memory thing is kind of nasty.  It's not clear to me why
>we need it at all, or why we have to keep all this device-specific
>logic in the kernel, or why it has to be an early quirk as opposed to
>a regular PCI quirk.  We had a thread [1] about it a while ago but I
>don't think anything got resolved.

I was reading that thread again and thinking what we could do to try to
resolve this. I will reply on that thread.

>But to try to make forward progress, I applied patch 1/5 (actually,
>the updated one from [2]) to my pci/misc branch with the updated
>commit log and code comments below.

thanks. I found the wording in the title odd as when I read "first" it
gives me the impression it's saying there could be more, which is not
possible.  Anyway, not a big thing. Thanks for rewording it.

Lucas De Marchi