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

From: Ingo Molnar
Date: Wed Aug 26 2015 - 03:27:06 EST

* Ingo Molnar <mingo@xxxxxxxxxx> 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().


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