[vbox-dev] cpu hotplug support
Alexander.Eichner at Sun.COM
Thu Apr 22 02:29:17 PDT 2010
any recent Linux kernel should support it. I used Ubuntu 9.10. Windows
is also supported but Windows Server 2008 R2 x64 Datacenter edition
implements CPU hot-add only.
The following commands configure the VM for CPU hotplugging:
VBoxManage modifyvm name --cpuhotplug on -- switches CPu hot-plugging on
VBoxManage modifyvm name --cpus <nr> -- sets the maximum number of
CPus the VM can have
VBoxManage modifyvm name --plugcpu <id> -- Adds the CPU with <id> to
the VM while it is off
VBoxManage modifyvm name --unplugcpu <id> -- Removes the CPU with <id>
from the VM while it is off, CPU 0 can't be removed.
Initiating hot-add/hot-remove events:
VBoxManage controlvm name plugcpu <id> -- Adds CPU <id> while the VM
VBoxManage controlvm name unplugcpu <id> -- Removes CPU <id> while the
VM is running.
Linux doesn't make use of new CPUs by default. You either need to
update the guest additions which includes a service handling the events.
If you don't want to update the guest additions you can also execute
the following command as root:
echo 1 > /sys/devices/cpus/cpu<id>/online
To eject a CPU without installed guest additions you have to do the
following before actually ejecting the CPU:
echo 1 > /sys/devices/LNXSYSTEM:00/device:00/ACPI0004:<i>/LNXCPU:<i2>/
The <i> and <i2> numbers don't need to be equal and they do not match
the <id> value used to enable a CPU. So you have to search for the
right CPU object unfortunately.
The reason behind is to prevent ejection of CPUs while the guest may
still use them. The above command will tell the kernel to disable the
Alexey Eremenko wrote:
> OK, since I have compiled a brand new VirtualBox, I would like to take
> a look at this feature too...
> 1. What are the commands for doing that ? (on host and on guest)
> 2. Which guest Linux kernels supported ?
> -Alexey Eromenko "Technologov"
> vbox-dev mailing list
> vbox-dev at virtualbox.org
Sitz der Gesellschaft:
Sun Microsystems GmbH, Sonnenallee 1, D-85551 Kirchheim-Heimstetten
Amtsgericht München: HRB 161028
Geschäftsführer: Thomas Schröder, Wolfgang Engels, Dr. Roland Bömer
Vorsitzender des Aufsichstrates: Martin Häring
More information about the vbox-dev