Re: [PATCH] i386 add Intel PEBS and BTS cpufeature bits and detection

Stephane Eranian
2006-11-17T12:29:48Z

On Fri, Nov 17, 2006 at 10:22:20AM +0100, Andi Kleen wrote:
> > The former
> > stores from/to information into MSRs and is very small (4 branches).
>
> P4 since Prescott has 16
>
Yes. I was talking about Core 2

> > On recent processors LBR and BTS can be constrained by priv level.
>
> Doesn't help for kernel debugging.
>
Well, if you set if for kernel level only, you do not capture user level
branches. This may happen if you crash soon after you've entered the kernel
and you have a small buffer.

--
-Stephane