Re: perf hw in kexeced kernel broken in tip

Peter Zijlstra
2010-12-08T19:06:56Z

On Wed, 2010-12-08 at 10:43 -0800, Yinghai Lu wrote:
> can you add sth force_... in command line to take over ownership of
> perf from BIOS or previous kernel ?

The problem is, you cannot steal the thing from the BIOS, you'll trample
on its settings and the next time it runs it will simply re-instate it.

And aside from probing the EN bit on boot there is no way of determining
this.

So forcing the state might get you an ill-functioning system.

> then still can use perf etc after we kexec from RHEL or SLES kernel to
> later kernel ( from 2.6.37)

I'm not sure why people would do that, but yeah I guess we can do
something like that.