Re: [Qemu-devel] [PATCH 1/1] If user doesn't specify a uuid, generate a random one

["Serge E. Hallyn" <serge@hallyn.com>]

Quoting Andreas Färber (afaerber@suse.de):
> Am 26.03.2012 17:13, schrieb Serge E. Hallyn:
> > Currently, if the user doesn't pass a uuid, the system uuid is set to
> > all zeros.  This patch generates a random one instead.
> > 
> > Is there a reason to prefer all zeros?
> 
> Yes, documented somewhere in the archives, we wanted to have
> reproducible defaults in QEMU (cf. MAC address, IP addresses) so that it
> doesn't change for each invocation or depending on host.

Thanks.  Though I don't know of a case offhand, I guess I could imagine
a case where a guest's userspace acts differently (and mis-behaves)
based on the random uuid...

> As a general rule, randomization should be done either explicitly (-uuid
> `uuidgen` or -generate-me-a-uuid) or via frontends such as libvirt.
> 
> If all zeros causes genuine problems then we should change the default,
> taking care of backwards compatibility as usual.

The bug this was in reply to is at http://pad.lv/959308 .  IIUC the main
problem is that our crash database uses the uuid, so users need to set
one to report bugs.  (There was also a suggestion that Microsoft requires
it for Logo Certification.)  My suggestion was also to have callers
specify it, but the crash db issue means we'd have to wrap all calls to
qemu.

So thanks - I understand if this patch doesn't make it upstream.  I'll
just carry a patch in our package in that case.

thanks,
-serge