Nouveau - Oct 2025 - [PATCH v6 0/5] Introduce bitfield and move register macro to rust/kernel/

On Wed Oct 8, 2025 at 1:37 AM CEST, Joel Fernandes
wrote:
> The Nvidia GPU architecture is little-endian (including MMU structures in
VRAM).
Yes, I'm aware (and I'd assume that there is no reason to ever change
that).

Just for the complete picture, there's also some endianness switch in the
NV_PMC_BOOT_1 register I think?
> All the CPU architectures our drivers support are expected to be
little-endian.
Technically, all Rust supported architectures are indeed little-endian.

However, the only constraint for the Nova project as by now is 64-bit only.

On Wed, Oct 08, 2025 at 12:23:40PM +0200, Danilo Krummrich
wrote:
> On Wed Oct 8, 2025 at 1:37 AM CEST, Joel Fernandes wrote:
> > The Nvidia GPU architecture is little-endian (including MMU structures
in VRAM).
> 
> Yes, I'm aware (and I'd assume that there is no reason to ever
change that).
> 
> Just for the complete picture, there's also some endianness switch in
the
> NV_PMC_BOOT_1 register I think?
> 
> > All the CPU architectures our drivers support are expected to be
little-endian.
> 
> Technically, all Rust supported architectures are indeed little-endian.
s390x is supported by rust as a tier2 output:
	https://doc.rust-lang.org/beta/rustc/platform-support/s390x-unknown-linux-gnu.html

so there really shouldn't be any reason why that platform couldn't add
rust support today, right?

thanks,

greg k-h

On Wed Oct 8, 2025 at 12:47 PM CEST, Greg KH wrote:
> On Wed, Oct 08, 2025 at 12:23:40PM +0200, Danilo Krummrich wrote:
>> On Wed Oct 8, 2025 at 1:37 AM CEST, Joel Fernandes wrote:
>> > The Nvidia GPU architecture is little-endian (including MMU
structures in VRAM).
>> 
>> Yes, I'm aware (and I'd assume that there is no reason to ever
change that).
>> 
>> Just for the complete picture, there's also some endianness switch
in the
>> NV_PMC_BOOT_1 register I think?
>> 
>> > All the CPU architectures our drivers support are expected to be
little-endian.
>> 
>> Technically, all Rust supported architectures are indeed little-endian.
>
> s390x is supported by rust as a tier2 output:
> 
https://doc.rust-lang.org/beta/rustc/platform-support/s390x-unknown-linux-gnu.html
>
> so there really shouldn't be any reason why that platform couldn't
add
> rust support today, right?
That's the one I also had in mind. :)

On 10/8/2025 6:23 AM, Danilo Krummrich wrote:
> On Wed Oct 8, 2025 at 1:37 AM CEST, Joel Fernandes wrote:
>> The Nvidia GPU architecture is little-endian (including MMU structures
in VRAM).
> 
> Yes, I'm aware (and I'd assume that there is no reason to ever
change that).
> 
> Just for the complete picture, there's also some endianness switch in
the
> NV_PMC_BOOT_1 register I think?
You are referring to old GPUs. NV_PMC_BOOT_1 does not have endianness switch for
Turing and later.
>> All the CPU architectures our drivers support are expected to be
little-endian.
> 
> Technically, all Rust supported architectures are indeed little-endian.
> 
Ok.
> However, the only constraint for the Nova project as by now is 64-bit only.
Ok.

Modern Nvidia GPUs only boot on x86 and ARM CPUs. There is BIOS/UEFI support
also that is needed for specific CPU architectures.

If we want to add a Kconfig patch enabling Nova only on x86/ARM, that'll be
Ok
with me.

hope this helps, thanks,

 - Joel