Re: cold plugging

[Kay Sievers <kay.sievers@vrfy.org>]

On Fri, Jan 13, 2006 at 02:15:30PM +0100, Treeve Jelbert wrote:
> I am running kernel-2.6.15 and udev-80 in a build everything from source 
> environment.
> 
> the kernel has lots of modules.
> 
> when the system is fully up, new hardware is detected and processed correctly 
> by udev.
> 
> my problem concerns hardware which is present before udevd starts, eg usb, 
> pcmcia, 1394, ....
> 
> udev does not seem to process any UEVENTS  for these things.  I tried 
> udevstart, but this seems to have no effect.

Don't use udev, udevsend and udevstart anymore, if you don't really need
to. The 2.6.15 kernel and udevd is all you need.

> Which program should be run to detect entries in /sys , trigger a UEVENT and 
> hence the execution of the udev rules, in order to load modules and create 
> device nodes?
> 
> I assume that somebody has a script or program that does this.
> 
> With previous kernels, I used udevsend as a hotplug driver and the relevant 
> modules did get loaded.

No, this never worked with udevsend. At the time udevsend is executed and
the modules too, all early events are already lost unless you have recorded
them in initramfs.

You need to retrigger all events after you have started udevd, just
write "add" to all "uevent" files in /sys and the events will be sent to
the udev daemon, which will create the device nodes and run modprobe and
other tools to setup the devices.

I'm using this:
	list=$(echo /sys/bus/*/devices/*/uevent)
	list="$list $(echo /sys/class/*/*/uevent)"
	list="$list $(echo /sys/block/*/uevent /sys/block/*/*/uevent)"
	for i in $list; do
	    case "$i" in
		*/device/uevent|*\**)
		    continue
		    ;;
		*/class/mem/*|*/class/tty/*)
		    first="$first $i"
		    ;;
		*/block/md*)
		    last="$last $i"
		    ;;
		*/*)
		    default="$default $i"
		    ;;
	    esac
	done

	# trigger the sorted events
	for i in $first $default $last; do
	    echo "add" > "$i"
	done


To wait for the events to finish (if you need to), I do:
	loop00
	while test -d /dev/.udev/queue; do
	    sleep 0.1;
	    test "$loop" -gt 0 || break
	    loop=$(($loop - 1))
	done

Kay


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