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Date: Wed, 20 Jan 2010 16:15:41 +0530
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>, Pekka Enberg <penberg@cs.helsinki.fi>,
       Peter Zijlstra <peterz@infradead.org>, ananth@in.ibm.com,
       Ingo Molnar <mingo@elte.hu>,
       Arnaldo Carvalho de Melo <acme@infradead.org>,
       utrace-devel <utrace-devel@redhat.com>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Masami Hiramatsu <mhiramat@redhat.com>,
       Maneesh Soni <maneesh@in.ibm.com>, Mark Wielaard <mjw@redhat.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP)
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Reply-To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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> >
> >What does the code in the jumped-to vma do?
> 
> 1. Write a trace entry into shared memory, trap into the kernel on overflow.
> 2. Trap if a condition is satisfied (fast watchpoint implementation).
> 
> >Is the instrumentation code
> >that corresponds to the uprobe handlers encoded in an ad hoc .so?
> 
> Looks like a good idea, but it doesn't matter much to me.
> 

That looks to be a nice idea. We should certainly look into this
possibility. However can we look at this option probably a little later?

Our plan was to do one step at a time i.e have the basic uprobes in
first and target the booster (i.e jump to the next instruction without
the need for single-stepping next). 

We could look at this option of using jump instead of int3 after we are
done with the booster.  Hope that's okay.

--
Thanks and Regards
Srikar