CPU Hotplug

[yeung]

Hey all,

I am using VirtualBox 4.1.18. My OS is MacOSX ver 10.7.4, processor is 2.7G Hz Intel Core i7, 4GB memory.

I used the ubuntu-12.04-server-i386.iso to install an Ubuntu VM. After my installation, I would like to test the 'CPU Hotplug' function. Initially my VM has 1 CPU. When I try to enter:

MacBook-Pro:Ubuntu1204 yeung$ vboxmanage controlvm Ubuntu1204 plugcpu 2

It did not work, and showed the following:

VBoxManage: error: CPU hotplug is not enabled
VBoxManage: error: Details: code NS_ERROR_INVALID_ARG (0x80070057), component SessionMachine, interface IMachine, callee nsISupports
Context: "HotPlugCPU(n)" at line 150 of file VBoxManageControlVM.cpp

I am new to VirtualBox, could somebody give me some hint to solve this? Many thanks!

[Perryg]

You need to enable it before it will work.
http://www.virtualbox.org/manual/ch09.html#cpuhotplug

[yeung]

Thanks a lot!

Now I am able to execute the plug/unplug command, however, still some issues:

When I tried to unplugcpu some CPU, VBox said that the CPU may still be used by the guest... as follows:

MacBook-Pro:Ubuntu1204 yeung$ VBoxManage controlvm Ubuntu1204 unplugcpu 3
VBoxManage: error: Hot-Remove was aborted because the CPU may still be used by the guest
VBoxManage: error: Details: code VBOX_E_VM_ERROR (0x80bb0003), component Console, interface IConsole, callee nsISupports
Context: "HotUnplugCPU(n)" at line 137 of file VBoxManageControlVM.cpp

Another issue is that if I use CPU hotplug to add a new CPU, it cannot be seen through 'x86info' in ubuntu immediately, after i reboot the ubuntu system, the new CPUs can be seen

Thanks again for helping me for these!

[Perryg]

Another issue is that if I use CPU hotplug to add a new CPU, it cannot be seen through 'x86info' in ubuntu immediately, after i reboot the ubuntu system, the new CPUs can be seen

The section from the users guide I sent you tells you what to do in this situation.
Hint: the last command in the section.