[Pkg-xen-devel] Bug#413601: Xen domUs vs. udev

[Thomas Schwinge]

Package: udev
Severity: important
X-Debbugs-CC: pkg-xen-devel at lists.alioth.debian.org

Hello!

When installing the udev package in a Xen domU, ``strange'' things
happen.


The following is a bit of guesswork, some hard facts are probably
missing, but I hope that the udev and / or Xen maintainers can make some
sense out of it.  I'm for now happy with having a usable Xen server
again...


The virtual ethernet devices that the Xen dom0 creates for providing net
access to a domU will have (unless overridden) a rather random mac
address.  Now, when having udev installed in a domU (by the way: the
problem seems to not show up with version 0.103-2) this has the effect
that (guesswork follows) udev thinks on each system (re)start that a new
ethernet device is available.  This can be seen in (a) the device no
longer being called `eth0', but `eth1', `eth2' on next restart and so on
and in (b) that the list in a domU's
`/etc/udev/rules.d/z25_persistent-net.rules' is getting longer and
longer:

#v+
[...]

# Xen virtual device (vif)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:07:f2:cb", NAME="eth11"

# Xen virtual device (vif)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:66:be:47", NAME="eth12"

# Xen virtual device (vif)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:16:3e:55:07:c7", NAME="eth13"
#v-


If you have had a simple...

#v+
auto eth0
        iface eth0 inet dhcp
        post-up ethtool -K eth0 tx off
#v-

... in the domU's `/etc/network/interface' that will obviously no longer
work, as the device won't be called `eth0' any longer, thus rendering the
domU's network connection unusable after having installed the udev
package.


A workaround is to either use udev version 0.103-2 in the Xen domUs or
completely remove the udev package from there.


I also think that it was neccessary to downgrade the dom0's version of
udev to 0.103-2 and rebuild the initrds to get things working again, but
I'd have to double-check that, which I'm not going to do right now.
(It's late already...)


Regards,
 Thomas
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