Re: fix dom0 crash on large machines

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Nov 23, 2009 at 10:42:08PM +0100, Christoph Egger wrote:
> 
> Hi!
> 
> On large machines, the phycpu_info array is limited
> to 32 and the array is used as apic index.
> 
> There are systems where the apic index of the first CPU
> starts with 16 and ends beyond of 32.
> 
> On such machines the Dom0 boot fails with a panic:
> 
>     cpu12 at mainbus0 apid 32panic: cpu at apic id 32 already attached?
> 
> (See PR port-xen/41755)
> 
> 
> This patch eliminates the limitation by removing
> X86_MAXPROCS.
> As a side effect, the patch also reduces the diff
> to sys/arch/x86/x86/cpu.c
> 
> http://www.netbsd.org/~cegger/xen_phycpu.diff

Looks good. But dom0 doesn't manage the LAPIC itself at this time;
if you're confident that the LAPIC will always be managed
by the hypervisor; you could remove completely the code in
#if NLAPIC > 0/#endif.

> 
> 
> I test it on a 48 CPU machine where the apic index
> goes from 16 to 75:

wow. Where can I get one of these ? :)

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--