RE: [Bpf] IETF BPF working group draft charter

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Jose E. Marchesi wrote: 
> > I'm really lost in this discussion.  All aspects of the ABI are a
> > required part of interoperability.  And one of the promises of this
> > IETF eBPF project is to provide for this interoperability.
> >
> > This is a very different situation from the binary ABI for Linux or
> > Windows, which has traditionally never been interoperable between
> > vendors, odd examples like iBCS2 [1] notwithstanding.
> 
> The situation is not that different from the perspective of the producers of the
> programs.  Even within the context of a single system the different vendors of
> compilers, assemblers, linkers, libc, and other tools need to coordinate and
> agree on conventions so they all produce compatible programs which are able
> to interoperate and run on the system.
> 
> The psABI is what provides for this interoperability, and it works just fine.
> 
> None of these psABI are maintained as standards in the strong and strict sense
> (ISO, ANSI, IETF, whatever) and I am just wondering about the convenience of
> doing so for the BPF ABI, given the nature of these.

The RISC-V calling convention is indeed maintained as a standard.
https://riscv.org/wp-content/uploads/2015/01/riscv-calling.pdf is the relevant
document by RISC-V International which per https://riscv.org/about/ is a standards
organization.  (I haven't participated in it, via the Confidential Computing Consortium I have interacted with some people who have.)

The eBPF Foundation could publish the equivalent of the riscv-calling.pdf document
above, but we (the IETF and BPF communities) decided the IETF was the best place
to publish such documents.  As such, I envision an IETF RFC for the BPF calling
convention that is very similar to the RISC-V standard one above.

Given the precedent, and the need in BPF, I don't see a problem.

> I reckon the perspective from the system side may be different.
> No more binary program solipsism :)
> 
> Example:
> 
> If I understood correctly from the thread, an IETF standard document is not
> supposed to be updated regularly.  Instead, it is expected to be carefully
> designed to rely on "codepoints" so all additions are optional and are released
> in their own document or supplement.
> 
> As someone who uses ABIs on the toolchain side, and who contributes to some
> of them, I am personally skeptical that schema can actually accomodate the
> reality of an alive and evolving ABI, especially one as young as BPF.  The
> resulting "authoritative" documents risk to be outdated more often than not,
> and end being a curiosity that nobody actually uses.
> 
> I would be happy to be proved wrong, and of course the WG is free to not share
> my concerns, but I have to voice them.

See the RISC-V document above.

Dave





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