Re: [PATCH v4 6/7] gpu: nova-core: add NVKV typed decoding

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

On Fri Oct 16, 2026 at 10:53 AM JST, Eliot Courtney wrote:
> Similar to the typed encoding layer, add some decoding type machinery.
> Add a simple macro `nvkv_decode!` which implements `Schema` for a struct
> by composing visit calls to each member. Add some common `Schema` kinds,
> such as `Array` which collects an array value into a fixed maximum size
> array, and `Required` which fails a decode if the value is not sent.
>
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>

A few (hopefully final) nits below.

<...>
> +impl<T: Default, const KEY_ID: KeyId, As> Schema for Key<T, KEY_ID, As> {
> +    type Target = T;
> +
> +    fn init() -> impl Init<Self> {
> +        Self::default()
> +    }
> +
> +    fn finish(&mut self) -> impl Init<Self::Target, Error> + '_ {
> +        const_assert!(
> +            size_of::<T>() <= 32,

Let's use a constant here again instead of a hardcoded value. We could
share that constant with `Encodable::encode`.

<...>
> +/// A schema field for an array value under the NVKV key `KEY_ID` that keeps at most `N` elements.
> +///
> +/// Unlike [`Array`], a longer value is truncated to its first `N` elements instead of failing the
> +/// decode.
> +pub(crate) struct TruncatingArray<T, const N: usize, const KEY_ID: KeyId> {
> +    vec: ArrayVec<T, N>,
> +}

This is basically a copy/paste of `Array`, with one line changing in
`visit`. Is it possible to just wrap `Array`, proxy the methods that are
identical, and only duplicate `visit`? (or better, have a private
function in `Array` that is called by both `visit` implementations to
reduce code duplication even more)