Subject: Re: linux-next: tip tree build warnings

From: Heiko Carstens <[email-masked]>
Date: Thu, 3 Sep 2009 14:13:26 +0200

On Thu, Sep 03, 2009 at 10:38:44AM +0200, Ingo Molnar wrote:
> * Stephen Rothwell <[email-masked]> wrote:
> > Today's linux-next build (powerpc ppc64_defconfig) produced these warning:
> > 
> > In file included from include/trace/ftrace.h:285,
> >                  from include/trace/define_trace.h:61,
> >                  from include/trace/events/timer.h:342,
> >                  from kernel/timer.c:50:
> > include/trace/events/timer.h: In function 'ftrace_raw_output_itimer_state':
> > include/trace/events/timer.h:280: warning: format '%lu' expects type 'long unsigned int', but argument 4 has type 'cputime_t'
> > include/trace/events/timer.h: In function 'ftrace_raw_output_itimer_expire':
> > include/trace/events/timer.h:317: warning: format '%lu' expects type 'long unsigned int', but argument 5 has type 'cputime_t'
> 
> Should be harmless with no runtime effects - the fix would be to 
> harmonize the cputime_t types across architectures.
> 
> > Introduced by commit 3f0a525ebf4b8ef041a332bbe4a73aee94bb064b ("timers: Add tracepoints for itimer") from the tip tree.
> > 
> > cputime_t is variously "u64", "unsigned long long" and "unsigned 
> > long" on different architectures.
> 
> Should be unsigned long i think. Most architectures use it as 
> unsigned long via include/asm-generic/cputime.h, except these three:
> 
>  arch/ia64/include/asm/cputime.h:typedef u64 cputime_t;
>  arch/powerpc/include/asm/cputime.h:typedef u64 cputime_t;
>  arch/s390/include/asm/cputime.h:typedef unsigned long long cputime_t;
> 
> Or we could eliminate the type altogether as well and standardize on 
> u64. Thomas?

s390 uses 64 bit cputime_t because we want the high resolution also in
32 bit kernels. So standardizing on u64 would be the preferred solution
for us.