Re: [PATCH 5/7] gpu: nova-core: add extra conversion functions and traits

["Alexandre Courbot" <acourbot@nvidia.com>]

On Mon Oct 27, 2025 at 12:40 AM JST, Danilo Krummrich wrote:
> On 10/26/25 3:39 PM, Alexandre Courbot wrote:
>> +#[cfg(CONFIG_32BIT)]
>> +/// Infallibly converts a `usize` to `u32` on 32-bit platforms.
>> +///
>> +/// This conversion is always lossless on 32-bit platforms, where a `usize` is the same size as a
>> +/// `u32`.
>> +///
>> +/// Prefer this over the `as` keyword to ensure no lossy conversions are performed.
>> +///
>> +/// This is for use from a `const` context. For non `const` use, prefer the [`FromAs`] and
>> +/// [`IntoAs`] traits.
>> +pub(crate) const fn usize_as_u32(value: usize) -> u32 {
>> +    kernel::static_assert!(size_of::<u32>() >= size_of::<usize>());
>> +
>> +    value as u32
>> +}
>
> Given that nova-core depends on CONFIG_64BIT, I assume you added this predicting
> that we'll move this to the kernel crate.

That's correct.

>
> For core code (and maybe other drivers) I think we also want the same thing for
> signed types, but I think it's also fine to add them when moving things into the
> kernel crate.

We'll definitely want this. Nova-core does not use require signed types,
which is why I omitted them for now - and also so save some labor as we
are still discussing the fitness of this design.