> how about if we pull ABI but leave ELF? The ELF architecture-specific configuration and extensions are traditionally part of the psABI. Chapter 4 Object Files. > > On Tue, May 23, 2023 at 12:08 PM David Vernet <void@xxxxxxxxxxxxx> wrote: >> >> On Tue, May 23, 2023 at 12:15:35PM -0500, David Vernet wrote: >> > On Tue, May 23, 2023 at 04:50:42PM +0000, Dave Thaler wrote: >> > > > -----Original Message----- >> > > > From: David Vernet <void@xxxxxxxxxxxxx> >> > > > Sent: Tuesday, May 23, 2023 9:32 AM >> > > > To: Dave Thaler <dthaler@xxxxxxxxxxxxx> >> > > > Cc: Jose E. Marchesi <jemarch@xxxxxxx>; bpf@xxxxxxxx; bpf >> > > > <bpf@xxxxxxxxxxxxxxx>; Erik Kline <ek.ietf@xxxxxxxxx>; Suresh Krishnan >> > > > (sureshk) <sureshk@xxxxxxxxx>; Christoph Hellwig <hch@xxxxxxxxxxxxx>; >> > > > Alexei Starovoitov <ast@xxxxxxxxxx> >> > > > Subject: Re: [Bpf] IETF BPF working group draft charter >> > > > >> > > > On Thu, May 18, 2023 at 07:42:11PM +0000, Dave Thaler wrote: >> > > > > Jose E. Marchesi <jemarch@xxxxxxx> wrote: >> > > > > > I would think that the way the x86_64, aarch64, risc-v, sparc, mips, >> > > > > > powerpc architectures, along with their variants, handle their ELF >> > > > > > extensions and psABI, ensures interoperability good enough for the >> > > > problem at hand, but ok. >> > > > > > I'm definitely not an expert in these matters. >> > > > > >> > > > > I am not familiar enough with those to make any comment about that. >> > > > >> > > > Hi Dave, >> > > > >> > > > Taking a step back here, perhaps we need to think about all of this more >> > > > generically as "ABI", rather than ELF "extensions", "bindings", etc. In my >> > > > opinion this would include, at a minimum, the following items from the current >> > > > proposed WG charter: >> > > > >> > > > * the eBPF bindings for the ELF executable file format, >> > > > >> > > > * the platform support ABI, including calling convention, linker >> > > > requirements, and relocations, >> > > > >> > > > As far as I know (please correct me if I'm wrong), there isn't really a precedence >> > > > for standardizing ABIs like this. For example, x86 calling conventions are not >> > > > standardized. Solaris, Linux, FreeBSD, macOS, etc all follow the System V >> > > > AMD64 ABI, but Microsoft of course does not. As Jose pointed out, such >> > > > standards extensions do not exist for psABI ELF extensions for various >> > > > architectures either. >> > > > >> > > > While it may be that we do end up needing to standardize these ABIs for BPF, >> > > > I'm beginning to think that we should just remove them from the current WG >> > > > charter, and consider standardizing them at a later time if it's clear that it's >> > > > actually necessary. I think this is especially true given that we don't seem to be >> > > > getting any closer to having consensus, and that we're very short on time given >> > > > that Erik is going to be proposing the charter to the rest of the ADs in just two >> > > > days on 5/25. >> > > > >> > > > Thanks, >> > > > David >> > > >> > > I can tell you it's very important to those who work on the >> > > ebpf-for-windows project that the ELF format is common between >> > > Linux and Windows so that tools like >> > > llvm-objdump and bpftool and other BPF-specific ELF parsing tools work for both >> > > Linux and Windows. We don't want Windows to diverge. >> > >> > Be that as it may, as I said before, to my knowledge there's no >> > precedence at all for standardizing ABI like this. Is there a reason >> > that you think Windows would diverge if we didn't standardize the ABI? >> > >> > I realize that I'm essentially saying, "Hey, pretend there's a standard >> > and don't diverge", but if that's what the entire rest of the industry >> > has done up until this point with all other psABIs, then it seems like a >> > reasonable expectation. >> > >> > > As such, I feel strongly that it is a requirement to be standardized right away. >> > >> > I have to respectfully disagree. I think there are much bigger fish to >> > fry, such as standardizing the ISA. Unless we really have a good reason >> > for diverging from industry norms, standardizing on ABI now feels to me >> > like we're putting the cart before the horse. >> >> Hi Dave et al, >> >> FYI, I just sent out a GitHub PR to remove these lines from the proposed >> WG charter: https://github.com/ekline/bpf/pull/5/files. I thought it was >> prudent to go ahead and open the PR now given how close we are to the >> 5/25 meeting, and that we don't seem to be any closer to getting >> consensus here. >> >> We can (and should) continue the discussion here, but my two cents is >> that unless there's a strong reason to keep ABI standardization within >> scope of the WG, that it makes sense to remove these bullets. >> >> That said, if the discussion dies down and/or doesn't continue, IMHO it >> would be prudent to merge the PR. I don't think our default position >> should be to deviate from well-established industry-wide precedence, >> with the onus being on those advocating for following industry norms to >> prove that we don't need to discuss it. Again, I may be missing some >> important context here, so apologies if that's the case. >> >> Thanks, >> David >> >> > Just to be very clear: I could be totally wrong here, and it could be >> > very important to deviate from industry norms and standardize ABI as >> > part of the initial WG charter. However, IMHO, a positive claim like >> > that needs to come with clear substantiation. The reality is that >> > deviating from industry norms and standardizing on ABI will have its own >> > costs and consequences. >> > >> > > Hence I would not want this removed from the charter unless there's an effort >> > > to do it somewhere else right away, which would seem to increase the coordination >> > > burden.
