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Re: [Qemu-devel] [PATCH 2/2] qemu-kvm: Add svm cpuid features

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH 2/2] qemu-kvm: Add svm cpuid features
Date: Sun, 12 Sep 2010 10:01:28 +0200
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20100806 Fedora/3.1.2-1.fc13 Lightning/1.0b2pre Thunderbird/3.1.2

 On 09/12/2010 09:16 AM, Alexander Graf wrote:

Depends on which Phenom you have. A Phenom II has NRIPSAVE but the old
Phenoms don't have it. For the SVM features it is not that important
what the host hardware supports but what KVM can emulate. VMCBCLEAN can
be emulated without supporting it in the host for example.
Well, let's have a phenom2 type for those new features (and any other features 
the phenom 2 has).  What's the point of using the name of existing hardware if 
it doesn't match that hardware?
Isn't that what cpu=host is there for? I don't want to see cpu type cluttering 
like we have it on ppc. I added the core2duo type for Mac OS X guests for which 
those are basically the oldest supported CPUs.

-cpu host is to all supported features into your guest.
-cpu phenom is to pretend you are running on a phenom cpu. This is useful for a migration farm for which the greatest common denominator is a phenom.

Those are separate use cases.

For the Phenom type, I honestly don't remember why, but there was also a good 
reason to add it. In fact, I use it today to have nested virt without -cpu host 
on hardware that's too new for my guests.

Curious, what guests balk at modern hardware but are fine with phenom?

Either way, I don't think we need a phenom2 type. The features additional are 
minor enough to not really matter and all use cases I can come up with require 
either -cpu host (local virt) or -cpu phenom (migration).

I'm fine with this (or with adding phenom2). But don't make phenom contain flags that real phenoms don't have.

error compiling committee.c: too many arguments to function

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