Re: ftrace breaks sparc64 build

Steven Rostedt
2009-01-06T02:07:46Z

On Tue, 6 Jan 2009, Heiko Carstens wrote:

> On Mon, Jan 05, 2009 at 05:14:22PM -0500, Steven Rostedt wrote:
> >
> > On Mon, 5 Jan 2009, Sam Ravnborg wrote:
> >
> > > > Is this all sparc cross compiler? I'm trying to reproduce it on x86 with
> > > > no avail :-(
> > > >
> > > > I would like to test other ways to change the macro, but to do so, I need
> > > > to get a compiler that will produce the warnings that you see. What
> > > > version of gcc are you using?
> > >
> > > I used crosstool to build a 3.4.5 gcc:
> >
> > Hmm, that's a pretty old compiler. I wonder if it wouldn't just help
> > if we just make the branch tracer dependent on the compiler used. That is.
> >
> > #if defined(CONFIG_PROFILE_ALL_BRANCHES) && (__GNUC__ >= 4)
> > #define if(cond) ...
> >
> > Or something :-/
>
> FWIW, on s390 with gcc 4.3.2 and an allyesconfig I get these:
>
> CC arch/s390/mm/extmem.o
> arch/s390/mm/extmem.c: In function 'segment_modify_shared':
> arch/s390/mm/extmem.c:572: warning: 'end_addr' may be used uninitialized in this function
> arch/s390/mm/extmem.c:572: warning: 'start_addr' may be used uninitialized in this function
> arch/s390/mm/extmem.c: In function 'query_segment_type':
> arch/s390/mm/extmem.c:259: warning: 'vmrc' may be used uninitialized in this function
>
> Switching off PROFILE_ALL_BRANCHES makes the warnings go away again.

Now that is really interesting. Because end_addr and start_addr are
initialized via functions:

if (x)
init_me(a, &y);
else
init_me(b, &y);

Which actually does not make sense why turning off PROFILE_ALL_BRANCHES
would affect this :-/

-- Steve