Messages in this thread | | | Date | Thu, 03 Mar 2011 15:47:25 -0500 | From | Zachary Amsden <> | Subject | Re: regression - 2.6.36 -> 2.6.37 - kvm - 32bit SMP guests don't boot |
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On 03/03/2011 02:06 AM, Nikola Ciprich wrote: >> No worries. What mess? >> > twice sending the same mail, nevermind :) > > >> I have two things you can try: >> >> first is running a single VCPU guest, if you have not done so already. >> > yup, UP guest is fine, just SMP doesn't work. > > >> Second is adding the bootparameter "clocksource=acpi_pm" to your guest >> kernel. >> > yes, this makes SMP work too! I just realized when You were asking about current > clocksource, I told You only host source, not the guest. So I checked now, > and (at least for UP, I guess for SMP it's the same), the clocksource is > kvm-clock! So seems like it got broken with the TSC changes? >
What is the exact kernel version you are using in the guest.
It appears that some earlier 32-bit versions of kvm-clock enabled kernels are still missing the required atomic check for backwards-time protection which would be needed on SMP. This explains why 64-bit is fine, 32-bit is not.
Why this change triggers that problem still is a slight mystery, logically it should only affect the system if you have an unstable TSC.
Zach
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