Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting

[Ingo Molnar <mingo@kernel.org>]

* Ingo Molnar <mingo@kernel.org> wrote:

> ... but back then I didn't feel like complicating an error recovery ABI for the 
> needs of the 1%, robust error handling is all about simplicity: if it's not 
> simple, tools won't use it.

And note that it needs to be 'simple' in two places for usage to grow naturally: 

  - the usage site in the kernel
  - the tooling side that recovers the information.

That's why I think that such a form:

	return err_str(-EINVAL, "x86/perf: CPU does not support precise sampling");

is obviously simple on the kernel side as it returns -EINVAL, and is very simple 
on the tooling side as well, if we are allowed to extend prctl().

Thanks,

	Ingo