On Tue, Jan 30, 2024 at 7:51 AM <dthaler1968@xxxxxxxxxxxxxx> wrote: > > Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > [...] > > > Although the Linux verifier doesn't support them, the fact that gcc > > > does support them tells me that it's probably safest to list the DW > > > and LDX variants as deprecated as well, which is what the draft > > > already did in the appendix so that's good (nothing to change there, I > > > think). > > > > DW never existed in classic bpf, so abs/ind never had DW flavor. > > If some assembler/compiler decided to "support" them it's on them. > > The standard must not list such things as deprecated. They never existed. So > > nothing is deprecated. > > Ack, I will remove the ABS/IND + DW lines from the appendix. > > > Same with MSH. BPF_LDX | BPF_MSH | BPF_B is the only insn ever existed. > > It's a legacy insn. Just like abs/ind. > > Should it be listed in the legacy conformance group then? > > Currently it's not mentioned in instruction-set.rst at all, so the opcode > is available to use by any new instruction. If we do list it in instruction-set.rst > then, like abs/ind, it will be avoided by anyone proposing new instructions. Yeah. The standard needs to mention it as legacy insn. It's such a weird ultra specialized insn introduced for one specific purpose parsing IP header. tcpdump only. Effectively.
