> -----Original Message----- > From: Yonghong Song <yonghong.song@xxxxxxxxx> > Sent: Monday, February 12, 2024 1:49 PM > To: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx>; Dave Thaler > <dthaler1968=40googlemail.com@xxxxxxxxxxxxxx> > Cc: bpf@xxxxxxxxxxxxxxx; bpf@xxxxxxxx; Dave Thaler > <dthaler1968@xxxxxxxxx> > Subject: Re: [Bpf] [PATCH bpf-next v2] bpf, docs: Add callx instructions in new > conformance group > > > On 2/12/24 1:28 PM, Jose E. Marchesi wrote: > >> +BPF_CALL 0x8 0x1 call PC += reg_val(imm) BPF_JMP | BPF_X > only, see `Program-local functions`_ > > If the instruction requires a register operand, why not using one of > > the register fields? Is there any reason for not doing that? > > Talked to Alexei and we think using dst_reg for the register for callx insn is > better. I will craft a llvm patch for this today. Thanks! Why dst_reg instead of src_reg? BPF_X is supposed to mean use src_reg. But this thread is about reserving/documenting the existing practice, since anyone trying to use it would run into interop issues because of existing clang. Should we document both and list one as deprecated? Dave
