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This combination of AMDprocessors is not suitable for SMP?

DISCUSSION Michael Tokarev 2 participants 2 messages Jul 23, 2009 KVM

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(yes there's no typo in $subject, it's an old formatting bug in printk).

When booting kvm guest on an AMD CPU, guest kernel prints this warning:

WARNING: This combination of AMDprocessors is not suitable for SMP.

be it SMP or UP guest. What's wrong with this "combination", and can it be fixed?

Thanks!

/mjt

#1 lore raw
Quoted 10 lines · Michael Tokarev

(yes there's no typo in $subject, it's an old formatting bug in printk).

When booting kvm guest on an AMD CPU, guest kernel prints this warning:

WARNING: This combination of AMDprocessors is not suitable for SMP.

be it SMP or UP guest. What's wrong with this "combination", and can it be fixed?

The qemu64 CPU model KVM injects into the guest lets it see an AMD K7 with 64bit extension. Only some AMD K7 (Athlon-MP) were certified for SMP support, so this code warns the user about an unsupported hardware. When running KVM you can ignore this warning, as it only applies to non-KVM capable processors and has no meaning for virtual SMP anyway.

If you like this warning to disappear, you can use "-cpu host" (and probably loose migration capability) or wait for the new safe64 CPU type, which will use family 15 instead of 6.

Regards,
Andre.

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Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448 3567 12
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