On Thu, 30 Jan 2020 at 11:38, Palmer Dabbelt <palmerdabb...@google.com> wrote: > * The semihosting comment doesn't define the semihosting call numbers, just > the > sequence to get to a call. That said, we haven't written down the Linux ABI > either -- though there's a much larger breadth of software out there that > implements it and won't break ABI compatibility, so maybe that's considered > sufficient in Linux land where it's not for semihosting.
I think the difference with Linux is that there's a clear single authoritative source for what the ABI is -- Linus's 'mainline' kernel (so for instance random out-of-tree forks, syscall patch proposals, etc that have not yet hit mainline don't count as being fixed-in-stone ABI). Semihosting doesn't have the same single clear "owning project", at least on the Arm side of things. I don't think a semihosting specification for RISC-V needs necessarily to be a very heavyweight thing -- it is, after all, a debug API at heart -- but I do agree that you should have one. thanks -- PMM
