linux-kernel - Re: [PATCH v3 0/2] efi/x86: Call set

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Message-ID: <CAMj1kXEGsnd5S3-nnCUNYJ5tVr2LU2BOkNp513OfU6A=jgVX2A@mail.gmail.com>
Date: Wed, 17 Jul 2024 09:46:51 -0700
From: Ard Biesheuvel <ardb@...nel.org>
To: Aditya Garg <gargaditya08@...e.com>
Cc: "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Hans de Goede <hdegoede@...hat.com>, 
	Lukas Wunner <lukas@...ner.de>, Kerem Karabay <kekrby@...il.com>, 
	Orlando Chamberlain <orlandoch.dev@...il.com>, 
	"sharpenedblade@...ton.me" <sharpenedblade@...ton.me>
Subject: Re: [PATCH v3 0/2] efi/x86: Call set_os() protocol on dual GPU Macs

On Wed, 17 Jul 2024 at 09:35, Aditya Garg <gargaditya08@...e.com> wrote:
>
> Hi Ard, Lukas
>
> Although the patch has been upstreamed, and works well for the Macs included,
> we have noticed another issue. For the Macs having a single GPU, in case a person
> uses an eGPU, they still need this apple-set-os quirk for hybrid graphics. This was
> not reported that time by anyone since people who use an eGPU are quite rare.
>
> I'm not sure how to handle this. Had a few ideas like:
>
> 1. Enable this for all T2 Macs.
> 2. Enable this for all Macs.
> 3. Add a kernel parameter.
>
> Would like your ideas and a possible fix for the same.
>

Hi,

Is this a theoretical concern? Or are you aware of any user that is
actually affected by this?

In any case, given the niche nature, enabling this more widely by
default does not seem like a great approach, as the risk for
regressions outweighs the benefit.

I could imagine the use of a EFI variable to opt into this, would that
work? It would have to be set only once from user space (using
efivarfs)