Re: [PATCH bpf-next v4 10/10] bpf, docs: Update instruction-set.rst for load-acquire and store-release instructions

Peilin Ye
2025-03-03T21:31:09Z

On Mon, Mar 03, 2025 at 11:14:47AM -0800, Alexei Starovoitov wrote:
> > Update documentation for the new load-acquire and store-release
> > instructions. Rename existing atomic operations as "atomic
> > read-modify-write (RMW) operations".
>
> rmw renaming looks like a churn. I don't think it adds clarity.
>
> > Following RFC 9669, section 7.3. "Adding Instructions", create new
> > conformance groups "atomic32v2" and "atomic64v2", where:
> >
> > * atomic32v2: includes all instructions in "atomic32", plus the new
> > 8-bit, 16-bit and 32-bit atomic load-acquire and
> > store-release instructions
> >
> > * atomic64v2: includes all instructions in "atomic64" and
> > "atomic32v2", plus the new 64-bit atomic load-acquire
> > and store-release instructions
>
> I think it's better for new groups to include only newly added insns.
> Also we probably should add barriers to kernel/llvm and only
> then update the doc with all insns together.
> Otherwise we very quickly get to atomicv3 and v4 groups.
> Naming wise I would call these two insns plus all barriers as
> barrier32 and barrier64 groups.
> cmpwait insn should probably be there as well.

Got it, I'll drop this patch from the series for now.

Thanks,
Peilin Ye