Nouveau - Oct 2025 - [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

On Wed, 2025-10-29 at 22:30 -0700, John Hubbard wrote:
> 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.
Sure, and this is exactly what is_ancient_gpu() does.  It tells you whether to
use boot42
instead of boot0.  It is the only function that looks at boot0.