Date: Tue, 26 Jan 2010 15:37:49 -0800 (PST)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tom Tromey <tromey@redhat.com>
cc: Kyle Moffett <kyle@moffetthome.net>, "Frank Ch. Eigler" <fche@redhat.com>,
       Oleg Nesterov <oleg@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Stephen Rothwell <sfr@canb.auug.org.au>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Peter Zijlstra <peterz@infradead.org>,
       Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Steven Rostedt <rostedt@goodmis.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>, linux-next@vger.kernel.org,
       "H. Peter Anvin" <hpa@zytor.com>, utrace-devel@redhat.com,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: linux-next: add utrace tree
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On Tue, 26 Jan 2010, Tom Tromey wrote:
> 
> In non-stop mode (where you can stop one thread but leave the others
> running), gdb wants to have the breakpoints always inserted.  So,
> something must emulate the displaced instruction.

I'm almost totally uninterested in breakpoints that actually re-write 
instructions. It's impossible to do that efficiently and well, especially 
in threaded environments.

So if you do instruction rewriting, I can only say "that's your problem".

But using the hardware breakpoints should automatically DTRT, both wrt 
threads _and_ wrt restarting. Sure, there's onyl a limited number of them, 
so if somebody wants more than that they are kind of screwed, but that's 
just how life is.

		Linus
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