On Thu, Jul 05, 2018 at 08:10:15PM +0300, Michael S. Tsirkin wrote: > On Thu, Jul 05, 2018 at 05:43:43PM +0100, Richard W.M. Jones wrote: > > On Thu, Jul 05, 2018 at 04:20:33PM +0200, Laszlo Ersek wrote: > > > QEMU does the right thing. If other hypervisors don't do this -- while > > > still taking and displaying the value in UUID / GUID textual format --, > > > they are wrong. The VMGENID spec from Microsoft > > > <http://go.microsoft.com/fwlink/?LinkId=260709> specifically mentions > > > "GUID". > > > > The MSFT spec does mention GUID, but it seems to me that it's only > > using GUID as an incidental example -- ie. that you might use the VM > > Generation ID to generate a GUID. Outside that example it > > consistently refers to the VM Gen ID as a 128-bit integer. It also > > says that it could be used as a "high entropy random data source", > > which is not in fact true if it's a UUID. > > > > It has to be said that after reading the spec again [the MSFT spec, > > not qemu's spec] and what other hypervisors are doing, I'm not sure > > qemu is doing the right thing here. > > > > Rich. > > So right now we have a "GUID" property. > We could always add an alternative property for people who want > to treat the ID as an integer. Would that address the issue?
TBH I'm fairly relaxed about this and I don't want to put in any effort to change anything. As Dan says later in the thread, no data is ever lost in the transformation. I have now written a "128 bit int" -> "GUID" mangler for virt-v2v's VM Generation ID handling code, so I'm happy enough. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/
