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Re: [libvirt] [PATCH 0/2] smbios fixes



On Thu, Dec 02, 2010 at 09:44:47PM +0200, Gleb Natapov wrote:
> On Thu, Dec 02, 2010 at 10:36:59AM -0700, Eric Blake wrote:
> > On 12/02/2010 05:47 AM, Daniel P. Berrange wrote:
> > > On Wed, Dec 01, 2010 at 05:12:08PM -0700, Eric Blake wrote:
> > >> In testing <smbios mode='host'/>, I noticed a couple of problems.
> > >> First, qemu rejected the command line we gave it (invalid UUID);
> > >> ifixingthat showed that all other arguments were being given literal
> > >> "" which then made the guest smbios differ from the host.  Second,
> > >> the qemu option -smbios type=1,family=string wasn't supported, which
> > >> lead to a spurious difference between host and guest.
> > >>
> > >> Meanwhile, qemu has a bug where '-smbios type=1,uuid=uuid' must parse
> > >> as a valid uuid, but is otherwise ignored.  The current qemu.git code
> > >> base _only_ sets smbios uuid from the '-uuid uuid' argument.  I've
> > >> filed a bug against the qemu folks asking whether this is intended (in
> > >> which case we have to modify libvirt to change the -uuid argument it
> > >> outputs when smbios is specified), or an oversight (hopefully the
> > >> latter, since it's still nice to correlate
> > >> /var/log/libvirt/qemu/....log with the XML uuid even when that differs
> > >> from the smbios uuid presented to the guest.)
> > > 
> > > Hmm, I thought the UUID we were passing in was a host UUID, but
> > > on closer inspection the type=1 table is definitely intended to
> > > carry the guest UUID. As such it doesn't make sense to populate
> > > that with anything other than the '<uuid>' from the guest XML.
> > > A host UUID should live elsewhere in the SMBIOS tables, likely
> > > in the type2 or type3 blocks
> > 
> > What does that mean to our XML?  Should we reject XML files where both
> > domain/uuid and domain/sysinfo/system/entry/uuid exist, but differ?
> > Both elements are optional, so it's feasible to see a guest uuid in
> > either location.  Meanwhile, I'm waiting on resolution to
> > https://bugzilla.redhat.com/show_bug.cgi?id=659122 to see if qemu will
> > be patched to let us stick the host's uuid in block 2 (base board) or
> > block 3 (chassis), in which case, we'll need to expand our XML to
> > support that notion.
> > 
> As I commented on the BZ use OEM strings type 11 smbios table to pass
> anything you want into a guest.
> 
> > I've also discovered that with current qemu, if both '-uuid uuid' and
> > '-smbios type=1,uuid=uuid' are specified, then -uuid takes precedence;
> > but either one of the two in isolation serves to set smbios block 1 with
> > the guest's uuid.
> > 
> I am surprised that libvirt still uses -uuid.

SMBIOS tables are only setup on x86 QEMU binaries, doing fullvirt.
On non-x86, or QEMU used for Xen paravirt, the -uuid arg value
would be used in other ways unrelated to SMBIOS. Thus replacing
-uuid $UUID with -smbiios type=1,uuid=$UUID would be wrong.

Regards,
Daniel


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