[PATCH] arm: fix handling of nr_cpus
Mark Salter
msalter at redhat.com
Thu Oct 13 08:17:47 EDT 2011
On Wed, 2011-10-12 at 18:26 +0100, Russell King - ARM Linux wrote:
> On Tue, Oct 11, 2011 at 09:31:04AM -0400, Mark Salter wrote:
> > The current code duplicates the setup of the cpu_possible bitmap in the
> > platform smp_init_cpus() function. Unfortunately, all of those places
> > have the same bug where the nr_cpus kernel parameter is ignored. This patch
> > consolidates the duplicated code in one place and fixes it to honor the
> > nr_cpus parameter. This is accomplished by having smp_init_cpus() return
> > the platform specific number of cores so that the caller (setup_arch) can
> > set up the cpu_possible bitmap correctly for all platforms.
>
> Who says every platform we're going to see will always have CPUs 0..N ?
> It's entirely possible that someone might want to have CPUs 0, 2, 3 as
> possible CPUs but omit CPU1 for platform reasons.
Good point. We could do that by not setting the cpu_present bit for the
CPU we want to omit. Or we could leave the current platform cpu_possible
setup as-is and add something like:
for (i = nr_cpu_ids; i < NR_CPUS; i++)
set_cpu_possible(i, false);
to setup_arch after the call to smp_init_cpus.
--Mark
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