Re: [PATCH] gpu: nova-core: require little endian

[Danilo Krummrich]

On Mon Apr 6, 2026 at 8:52 AM CEST, Eliot Courtney wrote:
> The driver already assumes little endian in a lot of locations. For
> example, all the code that reads RPCs out of the command queue just
> directly interprets the bytes.
>
> Make this explicit in Kconfig.
>
> Signed-off-by: Eliot Courtney <ecourtney@xxxxxxxxxx>
> ---
> The current code assumes little endian in a bunch of places. I think we
> should either explicitly decide to be generic on endianness or explicitly
> decide not to - having some handling sprinkled around in various
> locations seems confusing to me.
>
> I believe that currently e.g. `RUST` transitively depends on
> !CPU_BIG_ENDIAN, so this is more about making the decision explicit for
> nova-core rather than fixing any kind of hole.
> ---
>  drivers/gpu/nova-core/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/nova-core/Kconfig b/drivers/gpu/nova-core/Kconfig
> index a4f2380654e2..d8456f8eaa05 100644
> --- a/drivers/gpu/nova-core/Kconfig
> +++ b/drivers/gpu/nova-core/Kconfig
> @@ -3,6 +3,7 @@ config NOVA_CORE
>  	depends on 64BIT
>  	depends on PCI
>  	depends on RUST
> +	depends on !CPU_BIG_ENDIAN

Since we have DRM_NOVA select NOVA_CORE, this has to be added to DRM_NOVA as
well, otherwise you could forcefully select NOVA_CORE through DRM_NOVA without
considering !CPU_BIG_ENDIAN.

Note DRM_NOVA intentionally has select NOVA_CORE (instead of depends on), since
otherwise a user would need to enable NOVA_CORE in order to see DRM_NOVA in the
menuconfig in the first place.

>  	select AUXILIARY_BUS
>  	select RUST_FW_LOADER_ABSTRACTIONS
>  	default n
>
> ---
> base-commit: a7a080bb4236ebe577b6776d940d1717912ff6dd
> change-id: 20260406-fix-kconfig-3a059f622697
>
> Best regards,
> --  
> Eliot Courtney <ecourtney@xxxxxxxxxx>