Red Hat Bugzilla – Bug 804224
libvirt incorrectly identifies supported CPU types
Last modified: 2014-09-07 18:54:53 EDT
Tested in rawhide/f17alpha but seems present in f16
virsh capabilities shows Westmere
qemu-kvm -cpu shows valid cpu types
qemu-kvm -cpu ?
Creating a VM with cpu type westmere with following xml (snippit)
<cpu mode='custom' match='exact'>
Produces the following qemu-kvm command line
Changing xml to forbid fallback produces following message
error: unsupported configuration: CPU model Westmere is not supported by hypervisor
Created attachment 570719 [details]
virsh capabilities output
Created attachment 570720 [details]
libvirt xml snippet + kvm cpu commandline
Created attachment 570725 [details]
libvirt xml snippit with no fallback and resulting error
*** Bug 708927 has been marked as a duplicate of this bug. ***
may I ask what exactly is supposed to be the bug? I see that QEMU doesn't support Westmere, so libvirt uses '-cpu core2duo,<flags>...' to specify the CPU with correct features etc.
The host model you can see in virsh capabilities is reflecting just the host CPU capability and has nothing to do with any hypervisor.
Could you run that machine with "Nehalem" specified as cpu and check what will be specified in qemu's command line?
Sorry, I think I mixed xmls.
On a host that qemu-kvm -cpu ? says supports Nehalem and that shows Nehalem in virsh capabilities, setting libvirt xml to Nahlem drops down to
This is a result of our usage of -nodefconfig qemu option, which makes qemu ignore /etc/qemu/target-x86_64.conf where all the modern CPU models are defined. Try running qemu-kvm -cpu ? -nodefconfig, you will only see models in . Cooperation with qemu upstream (which has already been started, btw) is needed to fix this issue.
*** Bug 723739 has been marked as a duplicate of this bug. ***
any update on this?
Hello, we are still waiting for qemu to implement one feature that will make libvirt able to run it without -nodefconfig option.
Eduardo posted the patches upstream, but these are not in the code, yet.
We have also patches for the implementation in libvirt sent by Jiri, however these must wait for qemu to implement their functionality.
QEMU patches were pushed yesterday and are part of qemu-1.1-rc2. Corresponding libvirt change went in today as
Author: Jiri Denemark <email@example.com>
Date: Thu Apr 26 12:11:49 2012 +0200
qemu: Add support for -no-user-config
Thanks to this new option we are now able to use modern CPU models (such
as Westmere) defined in external configuration file.
Since this requires a qemu 1.1 command line arg, this isn't a very good backport candidate. qemu 1.1 and a new libvirt release will be in rawhide within a month, so just closing as UPSTREAM