HOWTO-udev_for_dev

   1 HOWTO use udev to manage /dev
   2
   3   This document describes one way to get udev working on a Fedora-development
   4   machine to manage /dev.  This procedure may be used to get udev to manage
   5   /dev on other distros, if you modify some of the steps.
   6
   7   This will only work if you use a 2.6 based kernel, preferably the most
   8   recent one.  This does not prevent your machine from using a 2.4
   9   kernel, if you boot into one, udev will not run and your old /dev will
  10   be present with no changes needed.
  11
  12
  13 NOTE NOTE NOTE NOTE NOTE NOTE NOTE
  14   This is completely unsupported.  Attempting to do this may cause your
  15   machine to be unable to boot properly.  USE AT YOUR OWN RISK.  Always
  16   have a rescue disk or CD handy to allow you to fix up any errors that
  17   may occur.
  18 NOTE NOTE NOTE NOTE NOTE NOTE NOTE
  19
  20
  21  - Build and install udev as specified in the README that comes with
  22    udev.  I recommend using the following build options to get the
  23    smallest possible binaries:
  24         make USE_KLIBC=true USE_LOG=false DEBUG=false
  25
  26  - disable udev from the boot process by running:
  27         chkconfig udev off
  28    or
  29         chkconfig --del udev
  30    as root.
  31
  32  - place the start_udev script somewhere that is accessible by your
  33    initscripts.  I placed it into /etc/rc.d with the following command:
  34         copy extras/start_udev /etc/rc.d/
  35
  36  - modify the rc.sysinit script to call the start_udev script as one of
  37    the first things that it does, but after /proc and /sys are mounted.
  38    I did this with the latest Fedora startup scripts with the patch at
  39    the end of this file.
  40
  41  - make sure the /etc/udev/udev.conf file lists the udev_root as /dev.
  42    It should contain the following line in order to work properly.
  43         udev_root="/dev/"
  44
  45  - reboot into a 2.6 kernel and watch udev create all of the initial
  46    device nodes in /dev
  47
  48
  49 If anyone has any problems with this, please let me, and the
  50 linux-hotplug-devel@lists.sourceforge.net mailing list know.
  51
  52 A big thanks go out to the Gentoo developers for showing me that this is
  53 possible to do.
  54
  55 Greg Kroah-Hartman
  56 <greg@kroah.com>
  57
  58
  59 ----------------------------------
  60 Patch to modify rc.sysinit to call udev at the beginning of the boot
  61 process:
  62
  63
  64 --- /etc/rc.sysinit.orig        2004-02-17 11:45:17.000000000 -0800
  65 +++ /etc/rc.sysinit     2004-02-17 13:28:33.000000000 -0800
  66 @@ -32,6 +32,9 @@
  67
  68  . /etc/init.d/functions
  69
  70 +# start udev to populate /dev
  71 +/etc/rc.d/start_udev
  72 +
  73  if [ "$HOSTTYPE" != "s390" -a "$HOSTTYPE" != "s390x" ]; then
  74    last=0
  75    for i in `LC_ALL=C grep '^[0-9].*respawn:/sbin/mingetty' /etc/inittab | sed 's/^.* tty\([0-9][0-9]*\).*/\1/g'`; do
  76
  77