linux-kernel - Re: [PATCH v3 2/2] gpu: nova-core: add boot42 support for next-gen GPUs

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Message-ID: <a1622011-6c86-4052-a808-31553e0b4916@nvidia.com>
Date: Wed, 29 Oct 2025 22:30:57 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Timur Tabi <ttabi@...dia.com>, "dakr@...nel.org" <dakr@...nel.org>
Cc: "lossin@...nel.org" <lossin@...nel.org>,
 "a.hindborg@...nel.org" <a.hindborg@...nel.org>,
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 "simona@...ll.ch" <simona@...ll.ch>, "tmgross@...ch.edu"
 <tmgross@...ch.edu>, "alex.gaynor@...il.com" <alex.gaynor@...il.com>,
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 Alexandre Courbot <acourbot@...dia.com>, "gary@...yguo.net"
 <gary@...yguo.net>, Alistair Popple <apopple@...dia.com>
Subject: Re: [PATCH v3 2/2] gpu: nova-core: add boot42 support for next-gen
 GPUs

On 10/29/25 6:44 PM, Timur Tabi wrote:
> On Wed, 2025-10-29 at 18:07 -0700, John Hubbard wrote:
>> Yes, but someone can still plug in a pre-Turing GPU and try to
>> boot up with nova-core.ko on the system.
>>
>> So it's important to avoid getting into trouble in that case.
> 
> Sure, but I think we don't want any real code that looks at boot0.  Nova should really just look
> at boot42 to determine any architecture.  So what we really want is to avoid accidentally

Oh I really understand your sentiment here. I'm all about, "use the new
hardware and never look back". :)

However, I don't want anyone to have to risk reading boot42 on some
ancient GPU (earlier than Fermi, even), with uncertain results.

And our HW team has promised to leave behind arch0==0, arch1==1 in
in boot0, more or less forever, specifically to help us out here.

With that in mind, I *do* want to read boot0 for the forseeable future,
as a guide to whether to look at boot42. I really think that is the
way to thread the needle here.


thanks,
-- 
John Hubbard