Re: [Qemu-devel] Byte ordering of VM Generation ID in Windows VMs

[Michael S. Tsirkin]

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?

> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
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