Re: [RFC 2/2] perf/core: change errno for sampling event not supported in hardware

From: Vineet Gupta
Date: Thu May 12 2016 - 02:29:07 EST

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In reply to: Peter Zijlstra: "Re: [RFC 2/2] perf/core: change errno for sampling event not supported in hardware"
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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)