Re: [Xen-devel] [PATCH]Check the values of MAX_VIRT_CPUS and NR_CPUSfor SMP

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Vendredi 21 Avril 2006 09:28, Tian, Kevin a écrit :
> From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
>
> >Sent: 2006年4月21日 15:26
> >
> >> >See how we solve this on x86 near the top of do_boot_cpu() in
> >> >arch/x86/smpboot.c. Essentially we allocate extra idle domains on
> >> >demand to give us enough idle vcpus for one per physical cpu.
> >> >
> >> >  -- Keir
> >>
> >> Yes, that's the same story on ia64 where we also allocate idle
> >> vcpu at do_boot_cpu(). That's why I'm not sure the real cause
> >> for Atsushi's issue.
> >
> >No, we don't create extra domains.  Therefore it there are more CPUs
> >than
> >VCPUs, something goes wrong...
>
> Yes, there's only one idle domain now. However I'm not sure
> why something will go wrong when NR_CPUS > MAX_VIRT_CPUS.
bvt has per VCPU data.  if #VCPU > #MAX_VIRT_CPUS, bvt reads/writes beyond the 
bounds!

Tristan.



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