(VM)Win Server 2008 R2 is only showing one CPU but has 4 allocated

Question

Xen Server 5.6 Sp2 The VM is Windows Server 2008 R2 Standard 4 vCPUs have been allocated

The machine has been rebooted and has correct version of xen tools installed.

In the device manager I see 4 cpus but in the task manager I only see one. In the performance monitor for xen I only see one cpu being utilized.

I have read that this issue could be attributed to single vs multi processor mode in windows but that seems to only be the case for 2003?

Solution

I got it worked out, I guess it was in single processor mode

msconfig -> boot options -> advanced -> select rescan for HAL

Reboot and then when I logged backed in it saw the rest of the cores and then I had to reboot one more time.

I did change the vcpu from 4 to 2 when it was shutdown but this step might not be needed.