Em Tue, Apr 27, 2021 at 01:38:51PM -0700, Andrii Nakryiko escreveu: > On Tue, Apr 27, 2021 at 5:34 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote: > > And tools that expect to trace a function can get that information from > > the BTF info instead of getting some failure when trying to trace those > > functions, right? > I don't think it belongs in BTF, though. My thinking was that since BTF is used when tracing, one would be interested in knowing if some functions can't be used for that. > Plus there are additional limitations enforced by BPF verifier that > will prevent some functions to be attached. So just because the > function is in BTF doesn't mean it's 100% attachable. Well, at least we would avoid some that can't for sure be used for tracing. But, a bit in there is precious, so probably geting a NACK from the kernel should be a good enough capability query. :-) Tools should just silently prune things in wildcards provided by the user that aren't traceable, silently, and provide an error message when the user explicitely asks for tracing a verbotten function. - Arnaldo
