[PATCH] devfs: Last little devfs cleanups throughout the kernel tree.

--------------------

A driver has been added to allow updating of Intel IA32 microcode,

accessible as both a devfs regular file and as a normal (misc)

character device.  If you are not using devfs you may need to:

accessible as a normal (misc) character device.  If you are not using

udev you may need to:

mkdir /dev/cpu

mknod /dev/cpu/microcode c 10 184

udev

----

udev is a userspace application for populating /dev dynamically with

only entries for devices actually present. udev replaces devfs.

only entries for devices actually present.  udev replaces the basic

functionality of devfs, while allowing persistant device naming for

devices.

FUSE

----

enable it to operate over diverse media layers.  If you use PPP,

upgrade pppd to at least 2.4.0.

If you are not using devfs, you must have the device file /dev/ppp

If you are not using udev, you must have the device file /dev/ppp

which can be made by:

mknod /dev/ppp c 108 0

as root.

If you use devfsd and build ppp support as modules, you will need

the following in your /etc/devfsd.conf file:

LOOKUP	PPP	MODLOAD

Isdn4k-utils

------------

     </sect1>

  </chapter>

  <chapter id="devfs">

     <title>The Device File System</title>

!Efs/devfs/base.c

  </chapter>

  <chapter id="sysfs">

     <title>The Filesystem for Exporting Kernel Objects</title>

!Efs/sysfs/file.c

terms are in use in the Mylex documentation; I have chosen to standardize on

the more generic "Logical Drive" and "Drive Group".

DAC960 RAID disk devices are named in the style of the Device File System

(DEVFS).  The device corresponding to Logical Drive D on Controller C is

referred to as /dev/rd/cCdD, and the partitions are called /dev/rd/cCdDp1

DAC960 RAID disk devices are named in the style of the obsolete Device File

System (DEVFS).  The device corresponding to Logical Drive D on Controller C

is referred to as /dev/rd/cCdD, and the partitions are called /dev/rd/cCdDp1

through /dev/rd/cCdDp7.  For example, partition 3 of Logical Drive 5 on

Controller 2 is referred to as /dev/rd/c2d5p3.  Note that unlike with SCSI

disks the device names will not change in the event of a disk drive failure.

    as the last process has closed it, all data is freed and /dev/initrd

    can't be opened anymore.

  root=/dev/ram0   (without devfs)

  root=/dev/rd/0   (with devfs)

  root=/dev/ram0

    initrd is mounted as root, and the normal boot procedure is followed,

    with the RAM disk still mounted as root.

procedure should create the /initrd directory.

If initrd will not be mounted in some cases, its content is still

accessible if the following device has been created (note that this

does not work if using devfs):

accessible if the following device has been created:

# mknod /dev/initrd b 1 250 

# chmod 400 /dev/initrd

    (if space is critical, you may want to use the Minix FS instead of Ext2)

 3) mount the file system, e.g.

    # mount -t ext2 -o loop initrd /mnt

 4) create the console device (not necessary if using devfs, but it can't

    hurt to do it anyway):

 4) create the console device:

    # mkdir /mnt/dev

    # mknod /mnt/dev/console c 5 1

 5) copy all the files that are needed to properly use the initrd

  root=/dev/ram0 init=/linuxrc rw

if not using devfs, or

  root=/dev/rd/0 init=/linuxrc rw

if using devfs. (rw is only necessary if writing to the initrd file

system.)

(rw is only necessary if writing to the initrd file system.)

With LOADLIN, you simply execute

# exec chroot . what-follows <dev/console >dev/console 2>&1

Where what-follows is a program under the new root, e.g. /sbin/init

If the new root file system will be used with devfs and has no valid

/dev directory, devfs must be mounted before invoking chroot in order to

provide /dev/console.

If the new root file system will be used with udev and has no valid

/dev directory, udev must be initialized before invoking chroot in order

to provide /dev/console.

Note: implementation details of pivot_root may change with time. In order

to ensure compatibility, the following points should be observed:

disk can be freed:

# umount /initrd

# blockdev --flushbufs /dev/ram0    # /dev/rd/0 if using devfs

# blockdev --flushbufs /dev/ram0

It is also possible to use initrd with an NFS-mounted root, see the

pivot_root(8) man page for details.

'c'	00-7F	linux/comstats.h	conflict!

'c'	00-7F	linux/coda.h		conflict!

'd'	00-FF	linux/char/drm/drm/h	conflict!

'd'	00-1F	linux/devfs_fs.h	conflict!

'd'	00-DF	linux/video_decoder.h	conflict!

'd'	F0-FF	linux/digi1.h

'e'	all	linux/digi1.h		conflict!