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

On Tue, Jun 09, 2015 at 02:12:39PM +0200, Peter Krempa wrote: > On Tue, Jun 09, 2015 at 13:05:35 +0100, Daniel Berrange wrote: >> On Tue, Jun 09, 2015 at 02:03:13PM +0200, Peter Krempa wrote: >>> On Tue, Jun 09, 2015 at 12:46:27 +0100, Daniel Berrange wrote: >>>> On Tue, Jun 09, 2015 at 01:22:49PM +0200, Peter Krempa wrote: >>>>> On Tue, Jun 09, 2015 at 11:05:16 +0100, Daniel Berrange wrote: >>>>>> On Tue, Jun 09, 2015 at 05:33:24PM +0800, Zhang Bo wrote: >>>>> > > ... > >>>>> 2) The guest OS sometimes needs to enable the memory region after ACPI >>>>> memory hotplug. The GA would be able to online such memory. For this >>>>> option we don't need to go through a different API though since it can >>>>> be compounded using a flag. >>>> >>>> So, are you saying that we should not be adding this to the >>>> virDomainSetMemory API as done in this series, and we should >>>> instead be able to request automatic enabling/disabling of the >>>> regions when we do the original DIMM hotplug ? >>> >>> Well, that's the only place where using the memory region GA apis would >>> make sense for libvirt. >>> >>> Whether we should do it is not that clear. Windows does online the >>> regions automatically and I was told that some linux distros do it via >>> udev rules. >> >> What do we do in the case of hotunplug currently ? Are we expectig the >> guest admin to have manually offlined the regions before doing hotunplug >> on the host ? > > You don't need to offline them prior to unplug. The guest OS handles > that automatically when it receives the request. Hmm, so if the guest can offline and online DIMMS automatically on hotplug/unplug, then I'm puzzelled what value this patch series really adds. Regards, Daniel