On Wed, Apr 29, 2020 at 07:43:04AM +0000, Ani Sinha wrote: > > > > On Apr 29, 2020, at 1:08 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > > > > On Wed, Apr 29, 2020 at 07:02:56AM +0000, Ani Sinha wrote: > >> > >> > >>> On Apr 29, 2020, at 12:27 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > >>> > >>> On Wed, Apr 29, 2020 at 06:54:52AM +0000, Ani Sinha wrote: > >>>> > >>>> > >>>>> On Apr 29, 2020, at 12:22 PM, Michael S. Tsirkin <m...@redhat.com> > >>>>> wrote: > >>>>> > >>>>> On Wed, Apr 29, 2020 at 06:11:20AM +0000, Ani Sinha wrote: > >>>>>> > >>>>>> > >>>>>>> On Apr 29, 2020, at 10:58 AM, Michael S. Tsirkin <m...@redhat.com> > >>>>>>> wrote: > >>>>>>> > >>>>>>> o if there's a need to disable > >>>>>>> just one of these, commit log needs to do a better job documenting the > >>>>>>> usecase. > >>>>>> > >>>>>> The use case is simple. With this feature admins will be able to do > >>>>>> what they were forced to do from Windows driver level but now at the > >>>>>> bus level. Hence, > >>>>>> (a) They need not have access to the guest VM to change or update > >>>>>> windows driver registry settings. They can enable the same setting > >>>>>> from admin management console without any access to VM. > >>>>>> (b) It is more robust. No need to mess with driver settings. Incorrect > >>>>>> settings can brick guest OS. Also no guest specific knowhow required. > >>>>>> (c) It is more scalable since a single cluster wide setting can be > >>>>>> used for all VM power ons and the management plane can take care of > >>>>>> the rest automatically. No need to access individual VMs to enforce > >>>>>> this. > >>>>>> (d) I am told that the driver level solution does not persist across a > >>>>>> reboot. > >>>>>> > >>>>>> Ani > >>>>> > >>>>> Looks like disabling both plug and unplug would also address these > >>>>> needs. > >>>> > >>>> No the driver level solution does not prevent hot plugging of devices > >>>> but blocks just hot unplugging. The solution I am proposing tries to do > >>>> the same but from the bus/hypervisor level. > >>> > >>> Why does the driver level solution need to prevent just hot unplugging? > >> > >> Because it not fair to prevent end users from hot plugging new devices > >> when it is the (accidental?) hot unplugging of existing devices which > >> causes issues. > > > > Accidental? So maybe what you need is actually something else then - > > avoid *removing* the device when it's powered down. > > You don’t get it. It is not hypervisor admins who are unplugging it. It is > the end users. Even RedHat customers want this feature. See following > resources: > https://www.redhat.com/archives/libvir-list/2020-February/msg00110.html > https://bugzilla.redhat.com/show_bug.cgi?id=1802592 > https://bugzilla.redhat.com/show_bug.cgi?id=1790899
That doesn't seem to require that hotplug keeps working. > My approach is much more fine grained than just disable everything approach > that we have for q35. For i440fx we can do better than that. > > > > > >>> > >>> > >>>> > >>>>> -- > >>>>> MST >
