Re: RFC: How to handle function tracing, frame pointers and -mfentry?

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 2012-04-27 at 13:31 -0700, H. Peter Anvin wrote:
> On 04/27/2012 01:27 PM, Sam Ravnborg wrote:
> >>
> >> My question is, how do I remove the dependency in kconfig based on the
> >> compiler?
> > 
> > Allow the user to select one of:
> > 1) function tracer
> > 2) frame pointer
> > 3) none of the above
> > 
> > This should be trivial to do in Kconfig language.
> > 
> > If "function tracer" is selected then use -mfentry if supported,
> > with a fallback to frame pointers.
> > 
> > This looks simple IMO and should be easy to implement too.
> > 
> 
> Except it is the wrong thing.  This is not the only user of frame
> pointer.  What I think you mean is remove the dependency in Kconfig, but
> force the frame pointer enabled if -mfentry is not supported.

You mean option 3?

3) Add frame pointers silently if gcc fails to build with gcc -pg.

Which I should have added, relies on the same thing as option 2:

2) Remove the select entirely.


-- Steve