Re: Problem with KVM-84 and more than 4 processors

Avi Kivity
2009-03-09T10:01:43Z

> Hi!
>
> I have a system with 2 processors and 4 cores each, which sums
> up to 8 processors in total. I installed the system with Gentoo.2008
> and KVM-84.
>
> Linux asok04 2.6.27-gentoo-r8 #1 SMP Tue Mar 3 11:34:26 CET 2009
> x86_64 Intel(R) Xeon(R) CPU X5355 @ 2.66GHz GenuineIntel GNU/Linux
>
> Everything is running fine as long as I do not change the default
> setting of CONFIG_NR_CPUS=4 in the kernel config:
>

That's the host kernel, right?

> asok04 ~ # lsmod
> Module Size Used by
> kvm_intel 39176 1
> kvm 137072 1 kvm_intel
> scsi_wait_scan 1664 0
> asok04 ~ #
>
> All KVM modules are loaded and I'm perfectly able to start and use
> virtual guests.
>
> However, if I increase CONFIG_NR_CPUS to any number higher than 4, the
> additional processors of my system are listed in /proc/cpuinfo, but
> this is the output of lsmod:
>
> asok04 ~ # lsmod
> Module Size Used by
> kvm 137072 283728377
> scsi_wait_scan 1664 0
> asok04 ~ #
>
> Manually loading the kvm_intel module fails with an "Cannot allocate
> memory" error. Also starting VMs fails since he is unable to find
> /dev/kvm.

Looks like a memory corruption issue. Please post your .config.

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