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From: | Avi Kivity |
Subject: | Re: [Qemu-devel] cpuid problem in upstream qemu with kvm |
Date: | Wed, 23 Dec 2009 12:32:26 +0200 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 |
On 12/22/2009 06:12 PM, Anthony Liguori wrote:
I think the only two Fully Correct approachs are to support a very specific CPU (e.g. Xeon-X5270) or provide the ability to individually tweak cpu flags.
Yes. By a curious coincidence these are what the hardware vendors define (unlike compat classes etc.).
The notion of compatibility classes should probably be left to management tools. We can make it a lot easier for them though by supporting turning point CPU models.
Agreed.
For instance, Xeon-X5570 should be a least common denominator for Nehalem processors. It's probably better for users too. It's easier for them to answer "do I have anything older than a Xeon-X5570" than to ask "do I have any Woodcrest class processors".I encounter this confusion a lot. I usually ask people whether they have a Nehalem processor when debugging something and their response is always, I have a Xeon-XYZ, is that Nehalem?
This is complicated by the fact that processors don't have straight-line development, and that marketing names don't correspond to anything. For example Xeon can be any of the Pentium 4, Core, Core 2, and Nehalem (and perhaps other) microachitectures. A newer Xeon is often introduced with an older core (usually for larger machines) than previously existing Xeons.
-- error compiling committee.c: too many arguments to function
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