Re: [RFC PATCH 3/9] perf: Add ability to dump part of the user stack

Frederic Weisbecker
2010-10-13T15:01:26Z

On Wed, Oct 13, 2010 at 09:22:17AM +0200, Peter Zijlstra wrote:
> On Wed, 2010-10-13 at 07:06 +0200, Frederic Weisbecker wrote:
> > +++ b/include/linux/perf_event.h
> > @@ -227,6 +227,12 @@ struct perf_event_attr {
> > __u32 bp_type;
> > __u64 bp_addr;
> > __u64 bp_len;
> > +
> > + __u64 __reserved_2;
> > + __u64 __reserved_3;
> > +
> > + __u32 ustack_dump_size;
> > + __u32 __reserved_4;
> > };
>
> Why add those two __u64 fields?

Because I suspect one day the breakpoint fields will need to be
extended. Some archs have quite fancy features for breakpoints
that include value comparison for example. So a field could be
used for the comparison operator and the other for the value
to be compared against.