core/udev/start_udev

#!/bin/sh

# mount /dev as a devtmpfs or tmpfs, depending on current kernel capability
# mount only, if it's not already mounted (e.g. after handover from initramfs)
# note: some video drivers require exec access in /dev
if ! /bin/mountpoint -q /dev ; then
	if ! /bin/sed -n '/devtmpfs/q1' /proc/filesystems ; then
		UDEVFS=devtmpfs
	else
		UDEVFS=tmpfs
	fi
	
	/bin/mount -n -t $UDEVFS udev /dev -o exec,nosuid,mode=0755,size=8M
fi

# make sure hotplugger is not set
echo > /proc/sys/kernel/hotplug

# since v155, udevd automatically copies /lib/udev/devices
# and creates /proc/{kcore,self/fd/{0,1,2}} symlinks

# launch udev daemon
/sbin/udevd --daemon

# coldplug devices and wait for the queue to be processed
/sbin/udevadm trigger --type=subsystems --action=add
/sbin/udevadm settle
/sbin/udevadm trigger --type=devices --action=add
/sbin/udevadm settle

# retry any failures
/sbin/udevadm trigger --type=failed --action=add
/sbin/udevadm settle