Re: [Xen-devel] [PATCH 0/4] CPU hotplug port from qemu-traditionnal to qemu-xen for 4.3.

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On 31/05/13 17:33, Anthony PERARD wrote:
> Hi all,
> 
> This series ports few patches from qemu-xen-traditionnal to qemu-xen
> (upstream). There is as little modification as possible on those patches so
> they *can not* be upstream as is. So this is only for 4.3. A proper series 
> will
> be done for 4.4.
> 
> There make possible to have CPU hotplug on qemu-xen.
> 
> A patch for libxl will follow, which make use of the old command line
> -vcpu_avail with qemu-xen. This command line will probably not be upstream.
> 
> BUG: There is an issue with SeaBIOS (used with qemu-xen). At SMP
> initialisation, SeaBIOS will count the number of CPU running, and the number 
> is
> always equal to maxvcpu when SeaBIOS expect less. This happen when we have
> something like:
> vcpus = 2
> maxvcpus = 8
> in the VM config file. Linux is fine with this and will use only $vcpus.  So
> the probleme is: an infinit loop in SeaBIOS.

To let you know, I just realize that QEMU 1.5 (we are using 1.3, I
think) already have everything needed for CPU hotplug. It will just be a
matter of plumbing libxl to use the cpu-add QMP command. But cpu-remove
QMP command seams to be missing from QEMU.

Regards,

-- 
Anthony PERARD

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