Re: [PATCH v3 0/2] efi/x86: Call set_os() protocol on dual GPU Macs

Aditya Garg
2024-07-24T16:34:07Z

> On 24 Jul 2024, at 10:01 PM, Lukas Wunner <lukas@wunner.de> wrote:
>
> ﻿On Wed, Jul 24, 2024 at 04:26:58PM +0000, Aditya Garg wrote:
>>>> On 24 Jul 2024, at 9:31 PM, Lukas Wunner <lukas@wunner.de> wrote:
>>> I note that on x86, the efistub walks over all PCI devices in the system
>>> (see setup_efi_pci() in drivers/firmware/efi/libstub/x86-stub.c) and
>>> retrieves the Device ID and Vendor ID. We could additionally retrieve
>>> the Class Code and count the number of GPUs in the system by checking
>>> whether the Class Code matches PCI_BASE_CLASS_DISPLAY. If there's
>>> at least 2 GPUs in the system, invoke apple_set_os.
>>
>> This also looks like a good idea, but I'm not well aware of the pci
>> quirks in the Linux kernel. So, would consider it a bug report for
>> the maintainers to fix.
>
> This is not a PCI quirk in the kernel. The efistub is a separate
> program. I'm saying that the efistub already walks over all PCI devices,
> it would be trivial to hook into this to count GPUs, recognize the T2
> device or do something else entirely.
>

I'll leave this to Ard. I'm really confused in choosing the best possible option here.

> Thanks,
>
> Lukas