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Date: Fri, 30 Nov 2001 19:37:23 +0100
From: Martin Dalecki <dalecki@evision-ventures.com>
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To: Davide Libenzi <davidel@xmailserver.org>
CC: Brian Gerst <bgerst@didntduck.org>, Simon Turvey <turveysp@ntlworld.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: Generating a function call trace
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Davide Libenzi wrote:
> 
> On Fri, 30 Nov 2001, Brian Gerst wrote:
> 
> > Davide Libenzi wrote:
> > >
> > > On Fri, 30 Nov 2001, Simon Turvey wrote:
> > >
> > > > Is it possible to arbitrarily generate (in a module say) a function call
> > > > trace?
> > >
> > > gcc has builtin macros to trace back or ( on x86 ) you can simply chain
> > > through %esp/%ebp
> >
> > That only works if you compile with frame pointers, which the kernel
> > turns off for performance reasons (due to register pressure on the x86).
> 
> I thought it was a general question not a kernel code one.
> Sure -fomit-frame-pointer is on inside the kernel.

With the , well exception, of the scheduler, which does the task
switching by
overwriting his own return address on the stack by the address of the
next jump point in a process, and needs the frame
pointer therefore ;-).
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