-
-udev - a userspace implementation of devfs
-
-For more information on the design, and structure of this project, see the
-files in the docs/ directory.
-
-To use:
-
-- You must be running a 2.6 version of the Linux kernel.
-
-- Make sure sysfs is mounted. udev will figure out where sysfs is mounted, but
- the traditional place for it is at /sys. You can mount it by hand by running:
- mount -t sysfs none /sys
-
-- Make sure you have the latest version of the linux-hotplug scripts. They are
- available at linux-hotplug.sf.net or from your local kernel.org mirror at:
- kernel.org/pub/linux/utils/kernel/hotplug/
- They are required in order for udev to work properly.
-
- If for some reason you do not install the hotplug scripts, you must tell the
- kernel to point the hotplug binary at wherever you install udev at. This can
- be done by:
- echo "/sbin/udev" > /proc/sys/kernel/hotplug
-
-- Build the project:
- make
-
-- Install the project:
- make install
-
- This will put the udev binary in /sbin, create the /udev and /etc/udev
- directories, and place the udev configuration files in /etc/udev. You
- will probably want to edit the namedev.* files to create custom naming
- rules. More info on how the config files are set up are contained in
- comments in the files, and is located in the documentation.
-
-- Add and remove devices from the system and marvel as nodes are created
- and removed in /udev/ based on the device types.
-
-- If you later get sick of it, uninstall it:
- make uninstall
-
-
-Things are still quite rough, and it's a bit beyond proof of concept
-code. Help is very much appreciated, see the TODO file for a list of
-things left to be done.
-
-If you want to build using klibc, use the Makefile.klibc file:
- - read the klibc/klibc/README file for how to set up the linux
- symlink properly.
- - make clean
- - make -f Makefile.klibc
-and marvel at the tiny binary you just created :)
-
-Any comment/questions/concerns please let me know.
-
-greg k-h
-greg@kroah.com
-
-
+udev - userspace device management
+
+For more information see the files in the docs/ directory.
+
+Important Note:
+ Integrating udev in the system is a whole lot of work, has complex dependencies
+ and differs a lot from distro to distro. All reasonable distros depend on udev
+ these days and the system will not work without it.
+
+ The upstream udev project does not support or recomend to replace a distro's udev
+ installation with the upstream version. The installation of a unmodified upstream
+ version may render your system unusable! There is no "default" setup or a set
+ of "default" rules provided by the upstream udev version.
+
+Requirements:
+ - 2.6 version of the Linux kernel.
+
+ - The kernel must have sysfs, netlink, and hotplug enabled.
+
+ - The proc filesystem must be mounted on /proc.
+
+ - The sysfs filesystem must be mounted at /sys. No other location
+ is supported.
+
+
+Operation:
+ - Udev creates and removes device nodes in /dev based on events
+ the kernel sends out on device discovery or removal
+
+ - Directly after mounting the root filesystem, the udevd daemon must be
+ started by an init script.
+
+ - From kernel version 2.6.15 on, the hotplug helper /sbin/hotplug should
+ be disabled with an init script before kernel modules are loaded.
+
+ - During bootup, /dev usually gets a tmpfs filesystem mounted which is
+ populated from scratch by udev (created nodes don't survive a reboot,
+ the /lib/udev/devices directory should be used for "static nodes").
+
+ - Udev replaces the hotplug event management invoked from /sbin/hotplug
+ by the udevd daemon, which receives the kernel events over netlink.
+
+ - All kernel events are matched against a set of specified rules which
+ make it possible to hook into the event processing.
+
+ - Copies of the rules files for all major distros are in the etc/udev
+ directory (you may look there how others distros are doing it).
+
+Compile Options:
+ prefix
+ Set this to the default root that you want to use only override
+ this if you really know what you are doing even then, you probably
+ don't do the right thing.
+ DESTDIR
+ Prefix for install target, used for package building.
+ USE_LOG
+ if set to 'true', udev is able to pass errors or debug information
+ to syslog. This is very useful to see what udev is doing or not doing,
+ it is enabled by default.
+ DEBUG
+ If set to 'true', very verbose debugging messages will be compiled
+ into the udev binaries. The actual level of debugging is specified
+ in the udev config file.
+ STRIPCMD
+ If udev is compiled for packaging an empty string can be passed
+ to disable the stripping of the binaries.
+ USE_SELINUX
+ If set to 'true', udev will be built with SELinux support
+ enabled. This is disabled by default.
+ USE_KLIBC
+ If set to 'true', udev is built and linked against klibc.
+ Default value is 'false'. KLCC specifies the klibc compiler
+ wrapper, usually located at /usr/bin/klcc.
+ EXTRAS
+ If set, will build the "extra" helper programs as specified
+ as listed (see below for an example).
+
+If you want to build the udev helper program cdrom_id and scsi_id:
+ make EXTRAS="extras/cdrom_id extras/scsi_id"
+
+Installation:
+ - The install target intall the udev binaries in the default locations,
+ all at boot time reqired binaries will be installed in /sbin.
+
+ - The default location for scripts and binaries that are called from
+ rules is /lib/udev.
+
+ - It is recommended to use the /lib/udev/devices directory to place
+ device nodes and symlinks in, which are copied to /dev at every boot.
+ That way, nodes for broken subsystems or devices which can't be
+ detected automatically by the kernel will always be available.
+
+Please direct any comment/question/concern to the linux-hotplug-devel mailing list at:
+ linux-hotplug-devel@lists.sourceforge.net