[PATCH] vmx: Parse vm.genid

[Daniel P. Berrangé]

On Mon, Aug 02, 2021 at 12:04:49PM +0100, Richard W.M. Jones wrote:
> On Mon, Aug 02, 2021 at 01:00:15PM +0200, Michal Prívozník wrote:
> > On 7/30/21 2:02 PM, Richard W.M. Jones wrote:
> > > On Thu, Jul 29, 2021 at 10:30:30AM +0200, Michal Privoznik wrote:
> > >> The VMware metadata file contains genid but we are not parsing
> > >> and thus reporting it in domain XML. However, it's not as
> > >> straightforward as one might think. The UUID reported by VMware
> > >> is not in its usual string form, but split into two signed long
> > >> longs. That means, we have to do a bit of trickery when parsing.
> > >> But looking around it's the same magic that libguestfs does:
> > >>
> > >> https://github.com/libguestfs/virt-v2v/blob/master/v2v/input_vmx.ml#L421
> > >>
> > >> It's also explained by Rich on qemu-devel:
> > >>
> > >> https://lists.nongnu.org/archive/html/qemu-devel/2018-07/msg02019.html
> > >>
> > >> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1598348
> > >> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> > >> ---
> > >>
> > >> I've successfully ran vmx2xmltest on an s390x machine which means that
> > >> there shouldn't be any endiandness problem.
> > >>
> > >>  src/vmx/vmx.c                                 | 30 +++++++++++++++++++
> > >>  .../vmx2xml-esx-in-the-wild-10.xml            |  1 +
> > >>  2 files changed, 31 insertions(+)
> > >>
> > 
> > > 
> > > Looked reasonable and seems to match the description here:
> > > 
> > > https://lists.nongnu.org/archive/html/qemu-devel/2018-07/msg02019.html
> > > 
> > > Reviewed-by: Richard W.M. Jones <rjones at redhat.com>
> > 
> > Pushed, thanks.
> > 
> > > 
> > > Out of interest, what is this being consumed by?  I will add this to
> > > virt-v2v when it goes upstream.
> > 
> > I don't recall all the specifics (it was John who implemented it), but
> > IIRC it was needed for Windows guests. Something about identifying them
> > uniquely. John?
> 
> Sure, I understand what it's used for.  I was just wondering if there
> are other consumers who want to pull the genID from VMware VMX files
> using libvirt.  Seems like something quite specific to V2V scenarios.

Could there even be a a case to be made for V2V to *not* preserve the
the genID value. eg If you see a genID in the existing config, then
write a /different/ genID value in the new VM, to indicate that this
new VM is a fork of the original VM ?


Regards,
Daniel
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