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Re: [Xen-devel] PV kernel boot parameter maxcpus has no effect?

from [Jan Beulich]

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Subject:	Re: [Xen-devel] PV kernel boot parameter maxcpus has no effect?
From:	"Jan Beulich" <jbeulich@xxxxxxxxxx>
Date:	Wed, 28 Apr 2010 08:22:28 +0100
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>>> Pasi Kärkkäinen 04/28/10 8:33 AM >>>
>On Wed, Apr 28, 2010 at 11:07:36AM +0800, Yuyang Du wrote:
>> Hi all,
>> 
>> I have a two-socket (each socket processor has 4 cores) machine, but only 
>> want to use one socket processor. I give pv
dom0 boot parameter maxcpus=4, but in fact there is no effect, other cpus 4-7 
are still used. Is this a bug or
something?
>> 
>
>You need to give _Xen_ (xen.gz) option dom0_max_vcpus=X

Yes and no - the other scenario also has its use case (i.e. have Dom0 initially 
just bring up a subset of the vCPU-s it
has been given).

However, given that the bringing up of secondary CPUs happens from common (even 
arch-independent) code, the whole issue
seems a little suspicious - namely what indication he uses to see that there 
are more than 4 vCPU-s in use by Dom0.

Jan

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