[PATCH] vmx: Parse vm.genid

[Richard W.M. Jones]

On Mon, Aug 02, 2021 at 12:12:08PM +0100, Daniel P. Berrangé wrote:
> 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 ?

https://images5.alphacoders.com/405/405572.jpg

Noooo!  Successfully converted VMs are definitely not forks and
shouldn't be used that way.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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