On Thursday 12 May 2016 01:06 AM, Peter Zijlstra wrote: > On Mon, May 09, 2016 at 10:53:43PM +0530, Vineet Gupta wrote: > >> > Right thats what I feared. But hold on, I don't think we need to change the ABI to >> > achieve what we want. Gosh why did I even take that path. >> > >> > Currently the errno switch case in perf_evsel__open_strerror() in doesn't handle >> > ENOTSUPP. So how about we add that - augmented with the same sample_period !0 >> > check to barf for lack of sampling support. >> > >> > Do you see anything wrong with that ? > > Should work I think. Tried that and doesn't even compile. Reconfirms what Vince said, ENOTSUPP is not exposed to userspace (being in include/linux and not include/uapi/linux)