The ifupdown plugin in NM 0.8 doesn't properly handle un-managed devices which use the "mapped" stanza in /etc/network/interfaces.

A user reported this error on Ubuntu 9.04 / Karmic development release.

The version of network-manager in question is: 0.8~a~git.20090812t221559.2e849a0

See original bug report at:

https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/413622

In this case, the default nm-system-settings.conf file was loaded with the contents:

[main]
plugins=ifupdown,keyfile

[ifupdown]
managed=false

I added a mapped stanza for eth0 to /etc/network/interfaces per the original bug report.  If I run NM 0.7.1, I can see the log message from SCPluginIfupdown_get_unmanaged_devices() that shows one entry being returned.  If I run NM 0.8, the corresponding log message always shows a 0 length.

It looks like the entries in /etc/network/interfaces are getting properly added to the well_known_interfaces, however they never get added to well_known_ifaces by the function udev_device_added().

This is due to the check:

 exported = (NMExportedConnection *) g_hash_table_lookup \
            (priv->iface_connections, iface);
 if (!exported) {

It appears that only non-lo "iface" stanza devices get added to iface_connections.  This check was newly added in NM 0.8.