Hi On Thu, Apr 13, 2017 at 12:25 AM Ben Warren <b...@skyportsystems.com> wrote:
> On Apr 12, 2017, at 1:22 PM, Marc-André Lureau <marcandre.lur...@gmail.com> > wrote: > > Hi > > On Thu, Apr 13, 2017 at 12:17 AM Ben Warren <b...@skyportsystems.com> > wrote: > > On Apr 12, 2017, at 1:06 PM, Marc-André Lureau <marcandre.lur...@gmail.com> > wrote: > > +Device Usage: > +------------- > + > +The device has one property, which may be only be set using the command > line: > + > + guid - sets the value of the GUID. A special value "auto" instructs > + QEMU to generate a new random GUID. > + > +For example: > + > + QEMU -device vmgenid,guid="324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87" > + QEMU -device vmgenid,guid=auto > > > The default will keep uuid to null, should it be documented? Wouldn't it > make sense to default to auto? > > There is no default - you have to supply a value. It’s up to whatever > software is managing VM lifecycle to decide what value to pass in. Always > setting to ‘auto’ will cause a lot of churn within Windows that may or may > not be acceptable to your use case. > > > Why would you have a vmgenid device if it's always null? Does that please > some windows use-cases as well? > > > I don’t get what you mean by this. What device is always null? Either > the device is instantiated or it isn’t. If not there, Windows will not > find a device and I don’t know how derived objects (Invocation ID, etc.) > are handled. > If you start a VM without specifying guid argument, you'll always have a genid null uuid, event after a migration (this could have been handled by qemu without requiring management layer, no?). I don't understand why auto would create more churn than what the management layer would do by setting new uuid for each VM started. Could you explain? > > > +The property may be queried via QMP/HMP: > + > + (QEMU) query-vm-generation-id > + {"return": {"guid": "324e6eaf-d1d1-4bf6-bf41-b9bb6c91fb87"}} > + > +Setting of this parameter is intentionally left out from the QMP/HMP > +interfaces. There are no known use cases for changing the GUID once QEMU > is > +running, and adding this capability would greatly increase the complexity. > > > Is this supposed to be not permitted? > > { "execute": "qom-set", "arguments": { "path": > "/machine/peripheral-anon/device[1]", "property": "guid", "value": "auto" } > } > > Is there any linux kernel support being worked on? > > This isn’t really relevant to the Linux kernel, at least in any way I can > think of. What did you have in mind? > > > Testing, but apparently we do have RFE for RHEL as Laszlo pointed out. > > OK, so you mean a guest driver. I do have one that needs work to go > upstream, but has been helpful to me in testing. > https://github.com/ben-skyportsystems/vmgenid-test > Thanks, that's exactly what I was looking for :) -- Marc-André Lureau