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Subject: Re: [PATCH v2 1/4] perf-events: Add support for supplementary
 event registers
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Stephane Eranian <eranian@google.com>
Cc: Lin Ming <ming.m.lin@intel.com>, Ingo Molnar <mingo@elte.hu>,
        Andi Kleen <andi@firstfloor.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Date: Wed, 02 Mar 2011 11:34:01 +0100
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On Wed, 2011-03-02 at 08:48 +0100, Stephane Eranian wrote:
> >> >        __u32                   bp_type;
> >> > -       __u64                   bp_addr;
> >> > -       __u64                   bp_len;
> >> > +       union {
> >> > +               __u64           bp_addr;
> >> > +               __u64           config1; /* extension of config0 */
> >> > +       };
> >> > +       union {
> >> > +               __u64           bp_len;
> >> > +               __u64           config2; /* extension of config1 */
> >> > +       };
> >> >  };
> >> >
> >> I don't see where those config0 or config1 are coming from.
> >
> > config0 means perf_event_attr::config.
> >
> yes.
> 
> > Peter suggested to extend the attr config space.
> > http://marc.info/?l=linux-kernel&m=129838808907525&w=2
> >
> Ok, I get it, it is cascading. that's fine. 

I initially put config and config0 in a union, but that made compilation
fail and fixing that up vs the benefit of actually having a config0,
which seemed near 0, led me to drop that part. Forgot to update the
comment though ;-)