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

[Pasi Kärkkäinen <pasik@xxxxxx>]

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.

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

-- Pasi


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