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SubjectRe: CPU boot problem on 2.6.0-test3-bk8
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On Thu, 2003-08-21 at 08:56, Andrew Theurer wrote:
> On Thursday 21 August 2003 09:58, Dave Hansen wrote:
> > On Thu, 2003-08-21 at 07:10, Andrew Theurer wrote:
> > > So we only loop for the actual number processors found in mpparse.c?
> > > This seems to work for me.
> >
> > I think there's a reason it was done that way. I think your patch
> > breaks the visws subarch, too.
> >
> > Could you mark up that loop a bit and printk a bit, so we can see which
> > continue you're missing?
> >
> > <pasting patch lazily in email because I can't be bothered to actually copy
> > it from the machine I"m working on> diff -urp
> > linux-2.6.0-test3-clean/arch/i386/kernel/smpboot.c
> > linux-2.6.0-test3-work/arch/i386/kernel/smpboot.c ---
> > linux-2.6.0-test3-clean/arch/i386/kernel/smpboot.c Wed Aug 20 19:54:29
> > 2003 +++ linux-2.6.0-test3-work/arch/i386/kernel/smpboot.c Wed Aug 20
> > 20:19:41 2003 @@ -1020,24 +1020,30 @@ static void __init
> > smp_boot_cpus(unsigne
> > Dprintk("CPU present map: %lx\n",
> > physids_coerce(phys_cpu_present_map));
> >
> > kicked = 1;
> > - for (bit = 0; kicked < NR_CPUS && bit < MAX_APICS; bit++) {
> > + for (bit = 0; kicked < NR_CPUS && bit < MAX_APICS; bit++, kicked++)
>
> This patch (plus your first one) seems to work. Perhaps the addition of
> kicked++ above helped? Attached is the boot log.

I missed that. But, it's incorrect. You're doubly incrementing kicked
in the case of CPUs that are booted correctly and getting to kicked >=
NR_CPUS a lot quicker. That's why you're booting correctly.

Secondly, we can actually boot up to NR_CPUS cpus, and we can *fail* to
boot a lot more than that. At least that's what the code is trying to
do. Whether it is "the right thing" is debatable.

--
Dave Hansen
haveblue@us.ibm.com

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