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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] no start on amd64 (was "Nothing happens")
Date: Sun, 31 Jul 2005 14:22:56 +0100
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To: qemu-devel@nongnu.org
Cc: Rudi Lippert <Rudi@lyrikpage.de>

On Sunday 31 July 2005 13:47, Rudi Lippert wrote:
> Should a qemu backtrace be 411 lines long?
> Actually, when I start qemu 0.7.1 (kqemu enabled, but makes no difference),
> it doesn't do anything. I hit CTRL-C to get a backtrace of the situation.
> Qemu has never worked on this setup, and the problem has always been the
> same.
> Any ideas?

Unless you overrode the default, qemu is compiled with optimization. In this 
case gcc and gdb will do their best, but it's normal for the debug 
information to be inaccurate. In particular there's no requirement that the 
compiler create a full stack frame, so you're relying on being able to track 
where the compiler happens to put things. Different toolchain versions are 
able to do this with different levels of accuracy.

If you're backtracing through dynamically generated code that will almost 
certainly confuse the debugger.

Once you hit a frame that gdb doesn't know about [???] all bets are off, and 
the rest of the backtrace is most likely random garbage.

Please read the 5th Q here:
http://www.geocities.com/nixling_gone/faq.html

Paul