Re: [PATCH v12 13/22] gpu: nova-core: Hopper/Blackwell: add FMC signature extraction

[Timur Tabi]

On Tue, 2026-06-02 at 20:53 -0700, John Hubbard wrote:
> I recall repeatedly hitting cases on one of the GPU architectures that
> used a shorter length, but I should go back and verify that it wasn't
> just a bringup "conclusion" that doesn't hold up after the dust settled.

So the lengths can actually vary by quite a bit:

gh100 len(ucode_hash)=48 len(ucode_sig)=384 len(ucode_pkey)=384
gb100 len(ucode_hash)=48 len(ucode_sig)=96 len(ucode_pkey)=97
gb10b len(ucode_hash)=48 len(ucode_sig)=384 len(ucode_pkey)=384
gb202 len(ucode_hash)=48 len(ucode_sig)=96 len(ucode_pkey)=97
gr100 len(ucode_hash)=48 len(ucode_sig)=96 len(ucode_pkey)=97

I'll ask around internally, but I think it's safe to say:

1) The hash must be 48 bytes
2) The signature could be 96 or 384 bytes
3) The pkey could be 97 (?????) or 384 bytes