Re: [PATCH v2 2/5] gpu: nova-core: add FbRange.len() and use it in boot.rs

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

On Thu Nov 27, 2025 at 9:53 AM JST, John Hubbard wrote:
> On 11/26/25 3:43 PM, Lyude Paul wrote:
>> I'm not sure this is necessary - for one, we could just use the .len() method
>> on the Range. As well - if we just implement Deref for FbRange (which I think
>> would be fine here) we could just use .len() through that.
>
> Hi Lyude!
>
> Good idea about the deref coercion. It has a minor type mismatch as-is,
> though: Range<u64>::len() returns usize, but FbRange::len() returns u64,
> which matches the callers that we have so far.

It's even worse than that, `Range<u64>::len()` simply doesn't exist. :)

`len()` is implemented through `ExactSizeIterator`, which specifies the
return type as `usize`. This obviously cannot provide a reliable result
when the range is u64, so the implementation was simply not done. See
[1] for evidence.

But having our own range type lets us slip our own `fn len(&self) ->
u64` implementation.

[1] https://doc.rust-lang.org/std/ops/struct.Range.html