On Thu, 10 Nov 2016 15:40:07 +0100 Joerg Roedel <joro@xxxxxxxxxx> wrote: > On Wed, Nov 09, 2016 at 01:01:14PM -0700, Alex Williamson wrote: > > Well, it's not like QEMU or libvirt stumbling through sysfs to figure > > out where holes could be in order to instantiate a VM with matching > > holes, just in case someone might decide to hot-add a device into the > > VM, at some point, and hopefully they don't migrate the VM to another > > host with a different layout first, is all that much less disgusting or > > foolproof. It's just that in order to dynamically remove a page as a > > possible DMA target we require a paravirt channel, such as a balloon > > driver that's able to pluck a specific page. In some ways it's > > actually less disgusting, but it puts some prerequisites on > > enlightening the guest OS. Thanks, > > I think it is much simpler if libvirt/qemu just go through all > potentially assignable devices on a system and pre-exclude any addresses > from guest RAM beforehand, rather than doing something like this with > paravirt/ballooning when a device is hot-added. There is no guarantee > that you can take a page away from a linux-guest. Right, I'm not advocating a paravirt ballooning approach, just pointing out that they're both terrible, just in different ways. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
