Re: [Qemu-devel] Enabling Hyperthreading for Guest

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 2011-09-21 at 15:02 +0200, erik.rull@rdsoftware.de wrote:
> Hi all,
> 
> I'm searching for a switch to enable hyperthreading for my Windows XP
> Guest. Currently I only get 2 cores available in the taskmanager but listed
> 4 or 8 (depending on the smp-switch).
> 
> After having read that XP supports only up to 2 cores but also with HT this
> should show me 4 cores.
> What must I do to get 4 cores visible in the Windows taskmanager?
> Is there a QEMU-BIOS option to enable?

See the extended -smp options:

-smp n[,maxcpus=cpus][,cores=cores][,threads=threads][,sockets=sockets]
                set the number of CPUs to 'n' [default=1]
                maxcpus= maximum number of total cpus, including
                offline CPUs for hotplug, etc
                cores= number of CPU cores on one socket
                threads= number of threads on one CPU core
                sockets= number of discrete sockets in the system

Try something like:

-smp 4,cores=2,threads=2,sockets=1

Alex