Re: [PATCH v3 4/8] gpu: nova-core: add NVKV encoder

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

On Wed Oct 7, 2026 at 12:43 PM JST, Alexandre Courbot wrote:
> On Mon Sep 28, 2026 at 5:42 PM JST, Eliot Courtney wrote:
> <...>
>> +impl EncodedStream {
>> +    /// Creates an empty stream.
>> +    fn new() -> Self {
>> +        // INVARIANT: An empty stream's byte length is 0, a multiple of `size_of::<u64>()`.
>> +        Self(Vec::new())
>> +    }
>> +
>> +    /// Appends a single `u64` to the stream.
>> +    fn push_u64(&mut self, value: u64) -> Result {
>> +        // INVARIANT: Appending `size_of::<u64>()` bytes keeps the byte length a multiple of
>> +        // `size_of::<u64>()`.
>> +        Ok(self.0.extend_from_slice(&value.to_ne_bytes(), GFP_KERNEL)?)
>> +    }
>> +
>> +    /// Appends `data` as bytes to the stream, zero-padded to a `u64` boundary.
>> +    fn extend_with_padding<T: IntoBytes + Immutable + ?Sized>(&mut self, data: &T) -> Result {
>> +        let bytes = data.as_bytes();
>> +        let padded = bytes.len().next_multiple_of(size_of::<u64>());
>> +        // Reserve so that a failed allocation can't leave the invariant violated.
>> +        self.0.reserve(padded, GFP_KERNEL)?;
>> +        self.0.extend_from_slice(bytes, GFP_KERNEL)?;
>> +        // INVARIANT: The padding ensures the total length remains a multiple of
>> +        // `size_of::<u64>()`.
>> +        Ok(self.0.extend_with(padded - bytes.len(), 0u8, GFP_KERNEL)?)
>> +    }
>> +}
>> +
>> +// The Deref to `&[u64]` relies on this alignment guarantee.
>
> nit: `Deref`
>
> ... and that's all I could find on this patch. I particularly like how
> the examples have turned out!

... although maybe the Sashiko comments are worth considering too. Nova
does depend on little-endian, but it probably wouldn't cost us much to
e.g. call `to_le_bytes` instead of `to_ne_bytes` to make the code more
portable.