From mboxrd@z Thu Jan  1 00:00:00 1970
From: msalter@redhat.com (Mark Salter)
Date: Mon, 03 Oct 2011 09:47:52 -0400
Subject: nr_cpus cmdline parameter not working
In-Reply-To: <20111001162357.GH11710@n2100.arm.linux.org.uk>
References: <1317224117.2580.84.camel@deneb.redhat.com>
	<20111001162357.GH11710@n2100.arm.linux.org.uk>
Message-ID: <1317649673.2703.0.camel@deneb.redhat.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Sat, 2011-10-01 at 17:23 +0100, Russell King - ARM Linux wrote:
> On Wed, Sep 28, 2011 at 11:35:16AM -0400, Mark Salter wrote:
> > I noticed that nr_cpus=1 doesn't appear to have any effect on a
> > pandaboard (and probably others from the looks of things). This
> > changes seems to be needed, but I'm not really sure if this is
> > the right thing or not.
> > 
> > diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
> > index ce65e93..a1198ac 100644
> > --- a/arch/arm/mach-omap2/omap-smp.c
> > +++ b/arch/arm/mach-omap2/omap-smp.c
> > @@ -117,6 +117,9 @@ void __init smp_init_cpus(void)
> >  		ncores = NR_CPUS;
> >  	}
> >  
> > +	if (ncores > nr_cpu_ids)
> > +		ncores = nr_cpu_ids;
> > +
> 
> This potentially affects all SMP platforms, so the patch needs to be
> bigger than this.
> 
> Also, I think the test above should be modified to use nr_cpu_ids
> rather than NR_CPUS, to be inline with what x86 does:
> 
>         /* nr_cpu_ids could be reduced via nr_cpus= */
>         if (possible > nr_cpu_ids) {
>                 printk(KERN_WARNING
>                         "%d Processors exceeds NR_CPUS limit of %d\n",
>                         possible, nr_cpu_ids);
>                 possible = nr_cpu_ids;
>         }
> 
> (This is essentially the same check that we're doing.)
> 
> Could you have a look at this and cook up another patch covering the
> other SMP platforms please?

Ok, I'll do that.