Re: [PATCH v11 02/20] gpu: nova-core: gsp: Extract usable FB region from GSP

[John Hubbard <jhubbard@nvidia.com>]

On 4/15/26 2:05 PM, Joel Fernandes wrote:
...
> +    /// Extracts the first usable FB region from GSP firmware data.
> +    ///
> +    /// Returns the first region suitable for driver memory allocation as a [`Range<u64>`].
> +    /// Usable regions are those that satisfy all the following properties:
> +    /// - Are not reserved for firmware internal use.
> +    /// - Are not protected (hardware-enforced access restrictions).
> +    /// - Support compression (can use GPU memory compression for bandwidth).
> +    /// - Support ISO (isochronous memory for display requiring guaranteed bandwidth).
> +    ///
> +    /// TODO: Multiple discontinuous usable regions of RAM are possible in
> +    /// special cases. We need to support it (to also match Nouveau's behavior).

Please let's not (ever) mention Nouveau in in-code comments. So far we
have held the line on that.

I think the TODO itself (again, without referring to Nouveau) could go into

    Documentation/gpu/nova/core/todo.rst

instead of here. But if you really must have it here, then OK.

> +    pub(crate) fn first_usable_fb_region(&self) -> Option<Range<u64>> {
> +        self.fb_regions().find_map(|reg| {
> +            // Filter: not reserved, not protected, supports compression and ISO.
> +            if reg.reserved == 0
> +                && reg.bProtected == 0
> +                && reg.supportCompressed != 0
> +                && reg.supportISO != 0
> +            {
> +                reg.limit.checked_add(1).map(|end| reg.base..end)
> +            } else {
> +                None
> +            }
> +        })
> +    }
>  }
>  
>  // SAFETY: Padding is explicit and will not contain uninitialized data.

With "Nouveau" references removed,

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard