Re: [PATCH v5 5/5] gpu: nova-core: add ChannelIdPool

[Yury Norov <ynorov@nvidia.com>]

On Fri, Aug 14, 2026 at 05:08:43AM -0400, Yury Norov wrote:
> On Fri, Aug 14, 2026 at 01:54:24PM +0900, Eliot Courtney wrote:
> > > 1. Provide a nz! macro to create constant non-zero things. Provide some
> > >    constants for common alignments
> > >
> > > Potentially, we could use build_assert! for cases it is provably
> > > non-zero but not a literal (although tbh not sure this is a good idea -
> > > at least not do this initially). 
> > >
> > > So either: nz!: const { NonZero::new(value).unwrap() }, or, nz!: some
> > > build assert gated construction of NonZero. A general nz! macro could
> > > also help ergonomics for other use cases too.
> > >
> > > That looks like this:
> > >
> > > pool.alloc_area(nz!(8), Alignment::AL_8)?;
> > 
> > Actually found that if we implement SizeConstants for Alignment then we
> > can get Alignment::SZ_4K etc almost for free.
> 
> Then maybe pass SZ_4K directly, and allow the alloc_area() to
> calculate the alignment:
> 
>         pool.alloc_area(nz!(8), SZ_4K)?;

Even worse, you can advertise the function like: allocate a contiguous
set of channel IDs enough to represent XXX bytes of memory with YYY
alignment. And that way, you'll be able to do:

          pool.alloc_area(SZ_8K, SZ_4K)?;

If my understanding of the function is right, it would be a clear
improvement, because the user now doesn't think about ID channels pool
as a set of bits, but an abstraction over the memory access technique,
which it really is.