[virt-tools-list] [virt-tool-list][PATCH]virt-manager: use host CPU configuration when creating new VM

Cole Robinson crobinso at redhat.com
Tue Nov 19 13:23:06 UTC 2013

On 11/19/2013 07:52 AM, Giuseppe Scrivano wrote:
> Chen Hanxiao <chenhanxiao at cn.fujitsu.com> writes:
>> From: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
>> This patch will use host CPU configuration automatically
>> when creating new VM.
> on what version of virt-manager is your patch based?  I tried to apply
> it to the current git master branch[1] but I get a conflict.
> In addition, I am not sure what is the impact of such a change, what are
> for example the downsides for a migration if we default to a more
> restrictive CPU configuration.

Indeed, just doing this unconditionally is not an option.

I will be working on this within the next few weeks. My plan is to add an
option 'Default CPU for New VMs' to the Preferences dialog. There will be 3

1) hypervisor default (no <cpu> block)
2) copy just the detected CPU model (so pentium3, Opteron_G4, etc)
3) full <cpu> copy (so either what this patch suggests, or use host-model

My plan is for the new virt-manager default to be option 2. Since libvirt's
host <cpu> detection has known issues with generating CPU configurations that
don't match reality, #3 isn't safe yet. But this still gives the user a chance
to make it the default if they aren't affected by the issues. When libvirt and
qemu straighten it all out and host-model is a safe option, we can change the
default in virt-manager.

- Cole

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