installing laptop-mode-tools lets renaming network interfaces fail -- archlinux

[hrehfeld]

Describe the bug I'm also running into this: https://bbs.archlinux.org/viewtopic.php?id=252364

After installing laptop-mode-tools, udev can't rename the network interface with 'device or resource busy.'.

To Reproduce Steps to reproduce the behavior:

1. Install Archlinux
2. configure network using predictable if names
3. install laptop-mode-tools
4. reboot, observe journalctl -u systemd-udevd or sudo udevadm test /sys/class/net/eth0

Expected behavior nothing. :-)

Important Information:

• Arch
• zen-kernel 5.5.6
• laptop-mode-tools 1.73.1-1
  • see above archlinux forum post for more info.

Workaround Just uninstall laptop-mode-tools.

[rickysarraf]

Yes. I am aware of it. There's a similar bug report on Debian. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=952506 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925944

There's a couple of issues here. Some of it is documented in the bug reports I've mentioned.

• eth0 used to be a generalized name in the past. So we chose to aggressively use it. THat is not the case any more. Especially with uniquely identifiable persistent names. So, the default has been dropped
• Ethernet devices have always had issues. If you go through the bug report on the upstream page as well as the Debian BTS, you'll see the maximum power saving issues with ethernet devices. Infact, ethernet throttling was disabled by default, for Debian for many many years. With the commit mention in the 1st bullet point, this situation too is avoided.
• The last point is about network management tools (NetworkManger etc) failing to act on the device after powersavings are enabled. That is something beyond the scope of laptop-mode-tools. It only does apply power savings, not just to the wired interface but also the wireless interface. If external daemons don't like such change, you can consider disabling the source of the problem (in laptop-mode-tools) or the destination (NM). The latter may be difficult to convince. So, easy route is to disable ethernet module in laptop-mode-tools. Ethernet is uncommon these days and disabling that module (which is what laptop-mode-tools now does by default) is the sensible thing to do today.