[PATCH 2/2] arm: make return_address available for ARM_UNWIND

[Russell King - ARM Linux]

On Thu, Jan 03, 2013 at 11:03:58AM -0500, Steven Rostedt wrote:
> On Thu, 2013-01-03 at 14:13 +0000, Russell King - ARM Linux wrote:
> > In summary, from what I can see in the patch, the reason why the ifdefs
> > are the way they are, and the reason the warning is there has not been
> > addressed; these patches just seem to be aimed just at removing a #warning
> > statement to make the warning go away.
> 
> You're correct that this patch does not solve any of theses issues. Now,
> I'm thinking that ftrace has matured where these issues don't exist, and
> where they do, it will only cause noise in the trace than anything
> serious. But, this needs to be looked deeper to make sure.

Looking back in the archives, it seems that we had a problem with ftrace
and the unwinder polluting the trace information:

http://lists.arm.linux.org.uk/lurker/message/20090604.201745.1c41ee6c.en.html

There's quite a bit of discussion in that thread about this which details
why we came up with what we have today.