Re: upgrade kvm with running vm

[Michael Tokarev <mjt@tls.msk.ru>]

08.10.2010 08:07, Teck Choon Giam wrote:
> On Thu, Oct 7, 2010 at 11:43 PM,  <sofa5000@lavabit.com> wrote:
>> hi everybody,
>>
>> is it a problem to update kvm (the kvm package (qemu-kvm on debian) with
>> the package manager) while some vms are turned on? or should i shutdown
>> all vms first?

If you update kvm userspace while some VMs are running, these
VMs will not "pick" the new userspace, they will continue
running by old userspace, until you restart them.  It's just
the same as if you upgrade, say, your shell while it's running -
new sessions will use new shell, alrady running will continue
running using old shell.

> From personal experience (install from source), there shouldn't be a
> problem to perform upgrade/update of qemu-kvm without shutting down
> those running VMs.  However, in order to use the updated version of
> the qemu-kvm, you will need to unload those loaded kvm-intel or
> kvm-amd and kvm kernel modules.  Such unloading of modules will need
> to shutdown all running VMs in order to successfully unload (rmmod)
> those kernel modules.  After unloading, you can reload the updated
> version by using modprobe or insmod after you have done depmod.

Do Not Mess With Kernel Modules (tm).  There's no need to.

/mjt