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Date: Mon, 2 Mar 2009 10:55:00 -0800
From: Arjan van de Ven <arjan@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Masami Hiramatsu <mhiramat@redhat.com>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
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       Rusty Russell <rusty@rustcorp.com.au>, "H. Peter Anvin" <hpa@zytor.com>,
       Steven Rostedt <srostedt@redhat.com>
Subject: Re: [RFC][PATCH] x86: make text_poke() atomic
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On Mon, 2 Mar 2009 13:36:17 -0500
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> * Arjan van de Ven (arjan@infradead.org) wrote:
> > > 
> > > Use map_vm_area() instead of vmap() in text_poke() for avoiding
> > > page allocation and delayed unmapping, and call
> > > vunmap_page_range() and local_flush_tlb() directly because this
> > > mapping is temporary and local.
> > > 
> > > At the result of above change, text_poke() becomes atomic and can
> > > be called from stop_machine() etc.
> > 
> > .... but text_poke() realistically needs to call stop_machine()
> > since you can't poke live code.... so that makes me wonder how
> > useful this is...
> 
> Hi Arjan,
> 
> Stop machine is not required when inserting a breakpoint. 

that is your assumption; when I spoke with CPU architects they
cringed ;(



-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org