On 2011-07-27 18:35, Vasilis Liaskovitis wrote: > Hi, > > On Mon, Jul 25, 2011 at 3:18 PM, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote: >> >> OK, hacks below plus the following three patches make CPU hotplug work >> again - with some exceptions. Here are the patches: >> >> 1. http://thread.gmane.org/gmane.comp.emulators.kvm.devel/76484 >> 2. http://thread.gmane.org/gmane.comp.emulators.qemu/110272 >> 3. http://thread.gmane.org/gmane.comp.emulators.qemu/110426 >> >> And here are the hacks (well, the first hunk is clearly a fix, the last >> one clearly a hack, /me still undecided about the rest): > > thanks for these. Testing a bit late here... > Applying these 3 patches + hacks/fix on master doesn't solve the > initial "CPU: not responding" dmesg hotplug issue on my setup. > The ACPI event is delivered correctly, but "echo 1 > > /sys/devices/system/cpu/cpuX/online" still fails. > e.g. tested with "-smp 1,maxcpus=2" > > Could you share your qemu-kvm command line? Nothing special: qemu-system-x86_64 /my/image -m 1G -snapshot -smp 2,maxcpus=3 \ -cpu host,-kvmclock > I have been trying 2.6.39 > guest kernel (as opposed to 3.0.2) but > I doubt that's the issue. > Can someone else confirm whether this solves the issue for their setup or not? > >> I see two remaining problems: >> - kvmclock is somehow broken, either in my guest kernel (OpenSUSE HEAD >> 3.0.0-2) or the host, -cpu host,-kvmclock works around sporadic >> guest lockups on echo 1 > /sys... > > could you explain this a bit further? specifying "-cpu host,-kvmclock" > avoids the lockups? I have tried Yes - apparently. I haven't checked if kvmclock is actually the problem or just changing the boundary conditions so that the issue no longer shows up here. > adding this to my command line but didn't help (but then again my > problem is not guest lockups: the onlining fails) > >> - Seabios tends to lock up once every few system_reset after some >> CPU has been hot-added - also in TCG mode. It seems to dislike any >> setup of #CPUs > smp_cpus (whatever that implies in details). > > I always get a lockedup seabios when rebooting after a hotplug attempt > with these patches (or with my initial vcpu_dirty workaround FWIW) Yes, this problem is most likely independent of the above. I even got those lockups when creating smp_cpus+1 vcpus in pc_cpus_init. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
