On Tue, Jul 19, 2011 at 07:40:55PM +0200, Vasilis Liaskovitis wrote: > Hello, > > I have encountered a problem trying to hotplug a CPU in my x86_64 guest setup. > You do everything right. It's qemu who is buggy. Since qemu need a patch for cpu hotplug to not crash it nobody tests it, so code bit rots. > host os: x86_64 debian-squeeze (2.6.32-5-amd64 kernel) > qemu-kvm: 0.14.1 or latest, both with the following (not-accepted) > patch to allow hotplug on the main_system_bus applied: > http://lists.gnu.org/archive/html/qemu-devel/2010-08/msg00850.html > guest os: x86_64 debian-testing with 2.6.39-2-amd64 kernel or debian > stable-squeeze with 2.6.32-5-amd64. > > example qemu-kvm command line (others have also been tried, this is > the simplest): > /opt/qemu-kvm/bin/qemu-system-x86_64 -enable-kvm -M pc -smp > 1,maxcpus=2 -drive file=/opt/images/wheezy.qcow2 -monitor stdio > > My first issue is regarding the acpi event delivery: I am running > "udevadm monitor" in my guest OS. > When I issue the cpu-hotplug on my qemu-monitor: > > qemu_monitor: cpu_set 1 online > > No udev-acpi event appears in the udevadm monitor of the guest. > > if i issue a pci-device hotplug command afterwards e.g. adding a NIC: > > qemu_monitor: pci_add auto nic > > then the cpu-hotplug acpi/udev events appear in the udev monitor: > > KERNEL[1311086666.114132] add > /devices/LNXSYSTM:00/device:00/LNXCPU:01 (acpi) > KERNEL[1311086666.119475] add /devices/system/cpu/cpu1 (cpu) > KERNEL[1311086666.120699] add > /devices/virtual/thermal/cooling_device1 (thermal) > UDEV [1311086666.158445] add /devices/system/cpu/cpu1 (cpu) > UDEV [1311086666.159925] add > /devices/virtual/thermal/cooling_device1 (thermal) > UDEV [1311086666.174848] add > /devices/LNXSYSTM:00/device:00/LNXCPU:01 (acpi) > > So only then is the./sys/devices/system/cpu/cpu1/ directory created. > > Is the acpi event supposed to be delivered to the guest OS immediately > after the cpu_set command? Or is what I > described expected behaviour? I am probably missing something, as > issuing a pci_add device command seems > irrelevant for the purpose of a CPU-hotplug acpi event. > > My second issue: after the successful creation of the cpu1 directory I > try to online the cpu: > > echo 1 > /sys/devices/system/cpu/cpu1/online > bash: echo: write error: Input/output error > > in the guest, dmesg reports: > > [ 2325.376355] Booting Node 0 Processor 1 APIC 0x1 > [ 2325.376357] smpboot cpu 1: start_ip = 9a000 > [ 2330.821306] CPU1: Not responding. > > and subsequent writes to /sys/devices/system/cpu/cpu1/online return > invalid argument. > Is there an obvious problem with the setup I have described? > > The same problem was observed with other -smp,maxcpus options as well > e.g. -smp 2,macpus=4 and trying to online cpu3. > I have also tried to specify "-cpu phenom" in the qemu command line, > with no effect. > > qemu-0.14.1 has seabios-0.6.1 or 0.6.2 I believe, both of which > include cpu hotplug support. I have also tried the newest > seabios (from repository) to be on the safe side with the same result, > so this doesn't seem to be a bios problem. > > thanks for any help, > > - Vasilis > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
