udev in initrd

[Thomas Woerner]

There are new FC3 test packages for udev usage in initrd:

http://people.redhat.com/twoerner/UDEV/FC3/

This is a minimal version without udev-persistent support and no busybox. It is using 
the normal nash initrd environment.


U S A G E
=========

- Install initscripts, mkinitrd and udev updates
- To use udev in initrd, set USE_UDEV and UDEV_INITRD in /etc/sysconfig/udev.
   udev will then use the normal /dev directory and will generate devices in there.
- udev can be started in a clean mounted ramfs on /dev by setting UDEV_RAMFS
- To get this ramfs /dev to your system, set UDEV_KEEP_DEV. Setting UDEV_KEEP_DEV
   also sets UDEV_RAMFS. /dev will be bind-mounted to your root directory, then.
   - Unset udev_owner in /etc/udev/udev.conf to get normal persimissions. Newer udev
     packages are not setting device ownerships or permissions, if the device already
     exists. But this is needed if you are keeping your /dev, because udev will
     generate devices with root ownership (there is no other user in initrd) and
     udevstart in rc.sysinit will not set correct permissions, then.
- Setting udev_remove will remove devices if the corresponding hardware device is
   gone e.g. for USB devices.


E X A M P L E   C O N F I G U R A T I O N
=========================================

/etc/sysconfig/udev
-------------------
...
USE_UDEV="yes"
UDEV_INITRD="yes"
UDEV_RAMFS="yes"
UDEV_KEEP_DEV="yes"

/etc/udev/udev.conf
-------------------
...
udev_owner="no"
udev_remove="yes"


W A R N I N G
=============

Do not overwrite your initrd images and make new grub entries, to have a sane 
fallback. Please be careful if you are using LVM or RAID. These are not tested, yet.


Thomas