Re: 2.6.16rc5 'found' an extra CPU.

[Dave Jones <davej@redhat.com>]

On Sat, Mar 04, 2006 at 04:42:38PM -0800, Andrew Morton wrote:
 > Dave Jones <davej@redhat.com> wrote:
 > >
 > > On Wed, Mar 01, 2006 at 07:55:25PM -0500, Chuck Ebbert wrote:
 > >  > In-Reply-To: <20060301230317.GF1440@redhat.com>
 > >  > 
 > >  > On Wed, 1 Mar 2006 18:03:17, Dave Jones wrote:
 > >  > 
 > >  > > (17:59:38:davej@nemesis:~)$ cat /sys/devices/system/cpu/cpu0/topology/core_siblings
 > >  > > 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
 > >  > > (17:59:47:davej@nemesis:~)$ cat /sys/devices/system/cpu/cpu1/topology/core_siblings
 > >  > > 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000002
 > >  > > 
 > >  > > Neither of these CPUs are HT / dual-core, so shouldn't these be the same ?
 > >  > 
 > >  > Those are bitmaps. 1 => only bit 0 is set => CPU 0 is all alone.
 > >  > 
 > >  > Did you really build a 256-CPU SMP kernel or is ACPI ignoring CONFIG_NR_CPUS
 > >  > or something?
 > > 
 > > Yes, it's =256.
 > > 
 > 
 > Is that the only way in which to trigger the bug?
 > 
 > If so, I'd be inclined to hold the fix back for 2.6.17.

not had chance to test Ashok's change yet (and probably won't until
at least Monday), but Andi's one-liner to limit x86-64's NR_CPUs
to 255 instead of 256 did the trick, and is a lot less invasive
for 2.6.16

		Dave