Usage

2.6 Kernels

The following examples demonstrate usage for one-time hardware detection.

Recommended usage for InitRD, if you do not have any modules you want to load manually:

---
hotplug2 --no-persistent --coldplug
------

Recommended usage for InitRD, if you have modules you want to load manually:

---
#!/bin/sh

echo "Starting detection"

hotplug2 --persistent --coldplug &
modprobe module1
modprobe module2
modprobe module3
killall -USR1 hotplug2
wait

echo "Detection over"
------

Please note that if you run hotplug2 and udevd simultaneously, both will suffer significant slowdown.

To have hotplug2 running permanently and perform coldplug, run: hotplug2 --persistent --coldplug

(note that hotplug2 will not daemonize itself, you have to use an equivalent to Debian's start-stop-daemon, or otherwise ensure it daemonizes)

The suggested base rules are in /examples.

2.4 Kernels

Since 0.8, hotplug2 provides a trivial binary "hotplug2-dnode" that forwards events taken from the obsolete /proc/sys/kernel/hotplug interface into netlink formatted as uevents, so that hotplug2 (or possibly also udev) can read them and work with them.

The hotplug2-dnode application also creates MODALIAS variable if missing and if it can be created.

You enable the support by: echo /sbin/hotplug2-dnode > /proc/sys/kernel/hotplug

Please note that udevtrigger will not work for 2.4 kernels. For this reason, "hotplug2-coldplug-2.4" application is provided; it handles coldplugging of PCI and USB devices. It works on 2.6 kernels as well, but "udevtrigger" does the job far better.

Therefore, run hotplug2 using this command:

hotplug2 [your usual params] --set-coldplug-cmd /path/to/hotplug2-coldplug-2.4

To simplify loading of modules, using the MODALIAS variable, you have to generate module aliases for your modules out of the busmaps. To do this, the application "generate_alias" has been written.

Usage of generate_alias:

 generate_alias --prefix /lib/modules/`uname -r` \
	--output /lib/modules/`uname -r`/modules.alias

Now, you can use hotplug2 with MODALIAS like on 2.6. See the base rules in the /examples directory.

To revise the steps, shortly:

• After a new installation of a 2.4 kernel, run generate_alias:

   generate_alias --prefix /lib/modules/`uname -r` \
  	--output /lib/modules/`uname -r`/modules.alias
   

• In your init script, run:

   echo /sbin/hotplug2-dnode > /proc/sys/kernel/hotplug
   hotplug2 --persistent --set-coldplug-cmd /sbin/hotplug2-coldplug-2.4
   

  (note that hotplug2 will not daemonize itself, you have to use an equivalent to Debian's start-stop-daemon, or otherwise ensure it daemonizes)
• That's it, you're done!

Please note that 2.4 support has not been thoroughly tested. Report bugs, send patches.