Re: [PATCH] gpu: nova-core: make pramin/buddy optional

[John Hubbard <jhubbard@nvidia.com>]

On 10/29/26 8:51 PM, Alexandre Courbot wrote:
> On Mon Oct 26, 2026 at 1:24 PM JST, Dave Airlie via B4 Relay wrote:
>> From: Dave Airlie <airlied@redhat.com>
...
>>  pub(crate) struct GpuMm<'gpu> {
>> -    buddy: GpuBuddy,
>> -    pramin: pramin::Pramin<'gpu>,
>> +    buddy: Option<GpuBuddy>,
>> +    pramin: Option<pramin::Pramin<'gpu>>,
>>      tlb: Pin<KBox<Tlb<'gpu>>>,
>>  }
>>  
>> @@ -85,28 +85,28 @@ impl<'gpu> GpuMm<'gpu> {
>>      pub(crate) fn new(
>>          bar: Bar0<'gpu>,
>>          chipset: Chipset,
>> -        buddy_params: GpuBuddyParams,
>> -        total_fb_end: VramAddress,
>> +        buddy_params: Option<GpuBuddyParams>,
>> +        total_fb_end: Option<VramAddress>,
> 
> This is related to the comment made by Sashiko, but in which cases are
> we expecting `total_fb_end` to be `None` here? Is this the same set of
> systems for which `buddy_params` will be `None`? If so both arguments
> should be merged into a new type to remove the ability to represent
> invalid state where one is `Some` and the other is `None`.

Neither, because the decision has to happen before GSP boot: on a
zero-FB chip the kernel-side RM sends GSP-RM a system-memory heap in the
boot arguments. The static info comes back after that.

Open RM makes it a per-chip HAL constant. See "bGpuArchIsZeroFb".


thanks,
-- 
John Hubbard