Re: [libvirt] [PATCH 0/8] logically memory hotplug via guest agent

On 2015/6/10 17:31, Daniel P. Berrange wrote: > On Wed, Jun 10, 2015 at 10:28:08AM +0100, Daniel P. Berrange wrote: >> On Wed, Jun 10, 2015 at 05:24:50PM +0800, zhang bo wrote: >>> On 2015/6/10 16:39, Vasiliy Tolstov wrote: >>> >>>> 2015-06-10 11:37 GMT+03:00 Daniel P. Berrange <berrange(a)redhat.com&gt;: >>>>> The udev rules are really something the OS vendor should setup, so >>>>> that it "just works" >>>> >>>> >>>> I think so, also for vcpu hotplug this also covered by udev. May be we >>>> need something to hot remove memory and cpu, because in guest we need >>>> offline firstly. >>>> >>> >>> >>> In fact ,we also have --guest option for 'virsh sevvcpus' command, which also >>> uses qga commands to do the logical hotplug/unplug jobs, although udev rules seems >>> to cover the vcpu logical hotplug issue. >>> >>> virsh # help setvcpus >>> ......................... >>> --guest modify cpu state in the guest >>> >>> >>> BTW: we didn't see OSes with udev rules for memory-hotplug-event setted by vendors, >>> and adding such rules means that we have to *interfere within the guest*, It seems >>> not a good option. >> >> I was suggesting that an RFE be filed with any vendor who doesn't do it >> to add this capability, not that we add udev rules ourselves. > > Or actually, it probably is sufficient to just send a patch to the upstream > systemd project to add the desired rule to udev. That way all Linux distros > will inherit the feature when they update to new udev. > Then, here comes the question: how to deal with the guests that are already in use? I think it's better to operate them at the host side without getting into the guest. That's the advantage of qemu-guest-agent, why not take advantage of it?