linux-kernel - Re: This combination of AMDprocessors is not suitable for SMP?

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Message-ID: <4A683CC0.90509@amd.com>
Date:	Thu, 23 Jul 2009 12:34:40 +0200
From:	Andre Przywara <andre.przywara@....com>
To:	Michael Tokarev <mjt@....msk.ru>
CC:	Linux-kernel <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: This combination of AMDprocessors is not suitable for SMP?

Michael Tokarev wrote:
> (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.

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