On 11/19/2013 10:39 PM, Chen Hanxiao wrote: > > >> -----Original Message----- >> From: Giuseppe Scrivano [mailto:gscrivan@xxxxxxxxxx] >> Sent: Tuesday, November 19, 2013 8:52 PM >> To: Chen Hanxiao >> Cc: virt-tools-list@xxxxxxxxxx >> Subject: Re: [virt-tool-list][PATCH]virt-manager: use > host CPU >> configuration when creating new VM >> >> Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx> writes: >> >>> From: Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx> >>> >>> 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. >> > My virt-manager git is a little old. I'll try to update it to the latest > >> 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. >> > libvirt may refuse to start the VM with a poorer CPU. > Though libvirt will never refuse to start with the host CPU model that it detects in <capabilities> XML. > And I think user will not be too surprise when they meet this scenario. > Just clear the old config, and press the existed button 'Copy host CPU > configuration' > will give them better performance and more feature. > We can doc this for users. > If migration fails because a user used 'copy host CPU', I agree that it's not a big issue and we can use libvirt's CPU APIs and <capabilities> reporting to predict when this will fail, and give a warning message about it in the migration dialog. However, users will most definitely be surprised if virt-manager defaults to 'Copy host CPU' and their guest crashes on startup: https://bugzilla.redhat.com/show_bug.cgi?id=870071 So right now turning it on by default is not an option. When I add the UI bit, users can make a one time config change to make 'copy host cpu' their default, until libvirt and qemu straighten this stuff out. - Cole _______________________________________________ virt-tools-list mailing list virt-tools-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/virt-tools-list
