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

[Frederic Weisbecker]

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.

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