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

[Peter Zijlstra]

On Thu, May 12, 2016 at 12:24:25PM +0530, Vineet Gupta wrote:
> On Thursday 12 May 2016 12:12 PM, Peter Zijlstra wrote:
> >> 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)
> > Durr, so what does userspace see?
> 
> It sees the "value" of ENOTSUPP, i.e. 524 but there is no symbolic reference to it :-)

Ah.. which might be a hint that nobody is actually explicitly testing
for this and we might just get away with changing the ABI.

Vince, what say you; shall we try and get away with it? ;-)