Re: [Xen-devel] Xen hypervisor dom0_vcpus option broken in Xen 3.4 ?

[Andrew Lyon <andrew.lyon@xxxxxxxxx>]

On Wed, Jan 13, 2010 at 9:38 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
> On Wed, Jan 13, 2010 at 8:36 PM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
>> Hello,
>>
>> while discussing things on xen-users we noticed this:
>>
>> (XEN) Xen version 3.4.2 (root@(none)) (gcc version 4.4.2 20091027 (RedHat 
>> 4.4.2-7) (GCC) ) Mon Dec 14 06:53:18 EET 2009
>> (XEN) Latest ChangeSet: unavailable
>> (XEN) Command line: dom0_mem=1G loglvl=all guest_loglvl=all com1=38400,8n1 
>> console=com1 dom0_vcpus=1
>> ..
>> (XEN) Dom0 has maximum 4 VCPUs
>> ..
>>
>> Has dom0_vcpus option name changed, or is it just broken?
>>
>> -- Pasi
>>
>>
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>> http://lists.xensource.com/xen-devel
>>
>
> Looks like it is called dom0_max_vcpus in 3.4.2:
>
> cat xen-3.4.2.gz |gzip -d | strings | grep cpus | grep dom0
> dom0_vcpus_pin
> dom0_max_vcpus
>
> Andy
>

Also see this thread
http://article.gmane.org/gmane.comp.emulators.xen.devel/69017, which
seems to suggest that  dom0_max_vcpus is parameter for the Xen
hypervisor (xen.gz) itself, while dom0_vcpus is for the dom0 kernel
and causes it to hot-unplug the "extra" cpu's so that they can be
(re)added later.

I believe the xen 2.6.18 kernel also supports booting pv domUs with
more max-cpus than active at startup, again so that they can be added
later.

I guess dom0_vcpus only works with Xen 2.6.18, I can find no trace of
it in the openSUSE Xen kernel source.

Andy

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