* Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> [100902 10:00]:
> On Thu, Sep 02, 2010 at 09:18:47AM -0700, Tony Lindgren wrote:
>
> > --- a/arch/arm/include/asm/smp_plat.h
> > +++ b/arch/arm/include/asm/smp_plat.h
> > @@ -39,4 +39,20 @@ static inline int cache_ops_need_broadcast(void)
> > #define UP(instr...) _str(instr)
> > #endif
> >
> > +static inline int smp_on_up(void)
> > +{
> > +#ifdef CONFIG_SMP_ON_UP
> > + int smp_on_up;
> > +
> > + asm( \
> > + SMP(mov %0, #0) \
> > + UP(mov %0, #1) \
> > + : "=r" (smp_on_up));
> > +
> > + return smp_on_up;
> > +#else
> > + return 0;
> > +#endif
>
> I think this is the wrong approach - rather than a function which tells us
> just if we are a SMP kernel running on UP, why not something which returns
> whether we're running on SMP and use that to eliminate some of these ifdefs?
Sure. Will has something like this in his patches:
static inline int cpu_is_part_of_mp_system(void)
{
u32 mpidr;
asm volatile("mrc p15, 0, %0, c0, c0, 5" : "=r" (mpidr));
return (mpidr >> 31) ? !(mpidr >> 30) : 0;
}
BTW, so far looks like we should only need this during init to set up things.
Regards,
Tony
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