From mboxrd@z Thu Jan  1 00:00:00 1970
From: Piotr Karbowski <piotr.karbowski@gmail.com>
Date: Tue, 17 Jan 2012 19:25:07 +0000
Subject: udev and existing /dev (devtmpfs)
Message-Id: <4F15CB13.1000703@gmail.com>
List-Id: <linux-hotplug.vger.kernel.org>
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To: linux-hotplug@vger.kernel.org

Hi,

After starting udev on the /dev which is devtmpfs the udev does not=20
'take over' already created nodes unless I add in the udev's init script

'udevadm trigger --type=DEvices --action=3Dchange'

    right after

'udevadm trigger --type=DEvices --action=ADd'

If there is no action=3Dchange, the /dev device mapper nodes looks like=20
(all are nodes, different permissions):
brw-rw---- 1 root disk 253,   0 Jan 17 19:51 /dev/dm-0
brw-rw---- 1 root disk 253,   1 Jan 17 19:51 /dev/dm-1
brw-rw---- 1 root disk 253,   2 Jan 17 19:51 /dev/dm-2
brw-rw---- 1 root disk 253,   3 Jan 17 19:51 /dev/dm-3
brw-rw---- 1 root disk 253,   4 Jan 17 19:51 /dev/dm-4
brw-rw---- 1 root disk 253,   5 Jan 17 19:51 /dev/dm-5
crw------- 1 root root  10, 236 Jan 17 19:51 /dev/mapper/control
brw------- 1 root root 253,   0 Jan 17 19:51 /dev/mapper/enc_root
brw------- 1 root root 253,   5 Jan 17 19:51 /dev/mapper/vg-dropzone
brw------- 1 root root 253,   4 Jan 17 19:51 /dev/mapper/vg-home
brw------- 1 root root 253,   3 Jan 17 19:51 /dev/mapper/vg-rootfs
brw------- 1 root root 253,   1 Jan 17 19:51 /dev/mapper/vg-swap
brw------- 1 root root 253,   2 Jan 17 19:51 /dev/mapper/vg-tmp

but after action=3Dchange it does look like:
brw-rw---- 1 root disk 253,   0 Jan 17 19:50 /dev/dm-0
brw-rw---- 1 root disk 253,   1 Jan 17 19:50 /dev/dm-1
brw-rw---- 1 root disk 253,   2 Jan 17 19:50 /dev/dm-2
brw-rw---- 1 root disk 253,   3 Jan 17 19:50 /dev/dm-3
brw-rw---- 1 root disk 253,   4 Jan 17 19:50 /dev/dm-4
brw-rw---- 1 root disk 253,   5 Jan 17 19:50 /dev/dm-5
crw------- 1 root root  10, 236 Jan 17 19:50 /dev/mapper/control
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/enc_root -> ../dm-0
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/vg-dropzone ->=20
../dm-5
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/vg-home -> ../dm-4
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/vg-rootfs ->=20
../dm-3
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/vg-swap -> ../dm-1
lrwxrwxrwx 1 root root        7 Jan 17 19:50 /dev/mapper/vg-tmp -> ../dm-2

The /dev/mapper/* become symlinks to /dev/dm-* (following udev rules).

The question is: in such scenario, where udev use already-created /dev=20
(whatever it is devtmpfs or maybe mdev-created), should we add the=20
action=3Dchange to the init script? If no, then what should we do to=20
udevize /dev?

Distro gentoo, udev-171, I have such issue on every box I use.

-- Piotr.