Nouveau - Nov 2025 - [PATCH v6 3/4] gpu: nova-core: make Architecture behave as a u8 type

On Sat Nov 8, 2025 at 2:08 PM JST, John Hubbard wrote:
> On 11/7/25 9:03 PM, Timur Tabi wrote:
>> On Fri, 2025-11-07 at 20:39 -0800, John Hubbard wrote:
>>> ?/// Enum representation of the GPU generation.
>>> -#[derive(fmt::Debug)]
>>> +#[derive(fmt::Debug, Default, Copy, Clone)]
>>> +#[repr(u8)]
>>> ?pub(crate) enum Architecture {
>>> +??? #[default]
>>> ???? Turing = 0x16,
>>> ???? Ampere = 0x17,
>>> ???? Ada = 0x19,
>>> @@ -142,6 +144,13 @@ fn try_from(value: u8) ->
Result<Self> {
>>> ???? }
>>> ?}
>> 
>> Does it make sense to designate a default Architecture?  Turing is not
a fallback for Ampere --
>
> Definitely not! However, we do want to use Architecture in places
> (register! and bitfield! macros) that expect u8 or u32, and that also
> expect to use integer defaults.
>
> So that's why we have to supply it. 
To be precise, we need to supply this because of a shortcoming in the
`register`` macro: it doesn't support read-only registers yet, and write
support requires a `Default` implementation for its fields. This is
subject to be fixed in the future but for now we need this little
workaround.

On Sat, 2025-11-08 at 20:45 +0900, Alexandre Courbot
wrote:
> To be precise, we need to supply this because of a shortcoming in the
> `register`` macro: it doesn't support read-only registers yet, and
write
> support requires a `Default` implementation for its fields. This is
> subject to be fixed in the future but for now we need this little
> workaround.
This definitely feels like something that needs a TODO comment.