Hi, this is patch to add maxvcpus support to xen xm command. It's using vcpu_avail bitmask and sets the number of vcpus to maxvcpus if present. If it's not present, old behavior is preserved. In domain config file you can define it as follows: maxvcpus = 4 vcpus = 2 this automatically sets vcpus to 4 and corresponding bitmask to present 2 vcpus in the guest with option to increase it up to 4 vcpus. If maxvcpus is not present, the old behavior for vcpus is preserved, ie. you can set vcpus to some number of vcpus to be used and the vcpu_avail is set appropriately to use all of them. Only when you use maxvcpus and vcpus new vcpu_avail value is calculated to show PV guest the desired number of vcpus only. It's been tested using RHEL-5 32-bit PV guest with maxvcpus = 4 and vcpus = 2 and also the previous setup of vcpus = 2 only... In both cases I was able to use 'xm vcpu-set {domainId} {numberOfVCPUs}' to increase move vcpu count from 0 to maxvcpus/vcpus so it was working as designed. Michal Signed-off-By: Michal Novotny