Re: [BUG] 2.5.63: ESR killed my box!

[Linus Torvalds]

On Wed, 26 Feb 2003, Ion Badulescu wrote:
> > diff -urpN -X /home/fletch/.diff.exclude virgin/arch/i386/kernel/smpboot.c
> > nonzero_apicid/arch/i386/kernel/smpboot.c
> > --- virgin/arch/i386/kernel/smpboot.c	Sat Feb 15 16:11:40 2003
> > +++ nonzero_apicid/arch/i386/kernel/smpboot.c	Wed Feb 26 13:02:10 2003
> > @@ -951,6 +951,7 @@ static void __init smp_boot_cpus(unsigne
> >  	print_cpu_info(&cpu_data[0]);
> >  
> >  	boot_cpu_logical_apicid = logical_smp_processor_id();
> > +	boot_cpu_physical_apicid = hard_smp_processor_id();
> >  
> >  	current_thread_info()->cpu = 0;
> >  	smp_tune_scheduling();
> 
> But this patch is for smpboot.c, which is not even compiled in for a UP 
> kernel...
> 
> Both Rusty and I had problems with a UP+APIC kernel running on an SMP box.

What about detect_init_APIC()?

That one currently does an unconditional

	boot_cpu_physical_apicid = 0;

and as far as I can see, this is the path taken by the UP case (because it 
doesn't even _try_ to find the SMP config tables).

What happens if you just remove that line (which means that the code 
further on will do

         */
        if (boot_cpu_physical_apicid == -1U)
                boot_cpu_physical_apicid = GET_APIC_ID(apic_read(APIC_ID));
                
which might be correct.

		Linus