A friend from my local Linux User Group has an old Samsung P28 laptop which he wanted to install Ubuntu on. Due to PAE issues he had to use the mini.iso image to install from rather than the Live or Alternate CDs. Post-install he did
sudo apt-get install ubuntu-desktop^ to add the desktop task, which worked fine to install Unity and all the other standard desktoppy bits.
However booting with the network cable unplugged would hang for ages waiting for the network. It would eventually time out and boot okay to the logon screen, once logged in wired or wifi could be used. Booting with the network cable attached would boot fine as expected.
The issue is that when you install using a wired network using the mini ISO you end up with an “eth0” stanza in /etc/network/interfaces. This is all well and good for that part of the install. When you add ubuntu-desktop^ which pulls in Network Manager is when it goes awry slightly.
Network Manager will ignore any network interface listed in /etc/network/interfaces. So the laptop worked when plugged in, and would boot normally, but when unplugged some service sat waiting for the network (eth0) to come up, which it wouldn’t because eth0 was being ignored by Network Manager. Once it timed out and booted the wireless network worked okay because /etc/network/interfaces had no reference to wlan0, no Network Manager was able to manage it, and get the wifi up.
The solution was to remove the “eth0” stanza from /etc/network/interfaces and reboot to test. All works fine now.
Now, the question is, is that a bug in Network Manager, or something else? I mean, it’s working as designed, but the use case of “installing from mini-iso then adding ubuntu desktop subsequently” is one I expect a few (not huge) number of people to do, so he won’t be alone in experiencing this..