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

[Andrew Lyon <andrew.lyon@xxxxxxxxx>]

On Wed, Jan 13, 2010 at 9:52 PM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
> On Wed, Jan 13, 2010 at 09:47:38PM +0000, Andrew Lyon wrote:
>> 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
>> >>
>> >>
>> >> _______________________________________________
>> >> Xen-devel mailing list
>> >> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> >> 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.
>>
>
> I've been using dom0_vcpus for Xen *hypervisor* with RHEL5/CentOS5 (which 
> includes Xen 3.1.2.)
>
> I think you mixed that up with xend-config.sxp dom0-cpus option, which
> is totally different thing, like Keir explains in that thread.

If you google dom0-cpus there are examples of other users passing the
argument to Xen or dom0, but yeh, good chance they are confused too
:-)

Andy

>
> But yeah, maybe now I remember it's called dom0_max_vcpus nowadays.
> Thanks.
>
> -- Pasi
>
>

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