On Tue, Dec 19, 2023 at 07:28:10PM -0800, Alexei Starovoitov wrote: > Right, but bringing the verifier into the "compliance picture" > makes the ISA standard incomplete. > Same can be said about nfp compliance. It's compliant with an ISA, > but the verifier will reject things it doesn't support. Yes, that's a good point. Especially for anything call related I think it's fine to say they are a mandatory part of the basic some coarse group, but a given program type might not support it, but that is enforced by the verifier as the compiler should not have to known about the program type. > All ld_imm64 and call insns look the same. The compiler emits > them the same way. > The src_reg encoding is what libbpf does based on compiler relocations. > > Then the verifier checks them differently and later JIT sees > _all_ ld_imm64 as one type of instruction. > Same with call insn. To x86/arm64/riscv JITs there is only one BPF CALL insn. Yup. Another case for ISA supported vs program type supported (and enforced by the verifier).
