Re: linux-next: tip tree build warnings

From: Martin Schwidefsky
Date: Mon Sep 07 2009 - 04:59:44 EST

On Thu, 3 Sep 2009 14:13:26 +0200
Heiko Carstens <heiko.carstens@xxxxxxxxxx> wrote:

> On Thu, Sep 03, 2009 at 10:38:44AM +0200, Ingo Molnar wrote:
> > * Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> > > 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.

The cputime_t type serves/served two purposes: 1) make it clear that
this is NOT a jiffie value, it is an architecture defined type with
architecture dependent semantic, 2) by redefining cputime_t to a
structure with a single embedded unsigned long I have been able to
identify all places in the kernel that do not use the proper cputime
functions. I'm not sure if we need 2) anymore.

blue skies,

"Reality continues to ruin my life." - Calvin.

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