Hm, interesting. So using a 64bit PV Lucid guest, I could use "xm vcpu- set 1" to change the vcpus from 2 to 1. This produced some worrying lines in dmesg though:
[ 48.208923] CPU0 attaching NULL sched-domain. [ 48.208940] CPU1 attaching NULL sched-domain. [ 48.270196] CPU0 attaching NULL sched-domain. [ 48.271423] Cannot set affinity for irq 6 [ 48.271433] Broke affinity for irq 7 [ 48.271439] Broke affinity for irq 8 [ 48.271444] Broke affinity for irq 9 [ 48.271450] Broke affinity for irq 10 [ 48.271455] Broke affinity for irq 11 [ 48.370172] SMP alternatives: switching to UP code But at least the guest kept running. Now a "xm vcpu-set 2" would have no visible effect on the guest. The vpcu number remained 1 but it did not hang either. But I was able to online the second cpu from within the guest. The kernel used was 2.6.32-41-server. That said, the recommended non-ec2 kernel flavours for running in PV guests would be server for 64bit and generic-pae for 32bit (mostly because those had drivers for virtual environments built-in instead of them being modules). @Frediano, would using the server flavour make a difference for you? And when would the hang occur, when adding or when removing a vcpu? And when running tail -f on the syslog, does that show any other hints? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1007002 Title: Xen VCPUs hotplug does not work To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1007002/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
