Subject: Re: [PATCH 3/3] tracing: Tracers that use CALLER_ADDR macros should select FRAME_POINTER

From: Anton Vorontsov <[email-masked]>
Date: Wed, 4 Feb 2009 18:36:43 +0300

On Wed, Feb 04, 2009 at 04:26:15PM +0100, Frédéric Weisbecker wrote:
[...]
> > @@ -136,6 +138,7 @@ config SCHED_TRACER
> >        select TRACING
> >        select CONTEXT_SWITCH_TRACER
> >        select TRACER_MAX_TRACE
> > +       select FRAME_POINTER
> >        help
> >          This tracer tracks the latency of the highest priority task
> >          to be scheduled in, starting from the point it has woken up.
> > --
> 
> 
> Looks right.
> 
> BTW, how behaves builtin_return_address in case of !FRAME_POINTERS ?
> I guess it would only work with the first caller builtin_return_address(0)

It depends on the architecture. On PowerPC we always have frame pointers,
thus __builtin_return_address(1..) will always work. On x86 it won't work
that way.

Thanks,

-- 
Anton Vorontsov
email: [email-masked]
irc://irc.freenode.net/bd2