1 udev - userspace device management
3 For more information see the files in the docs/ directory.
6 Integrating udev in the system is a whole lot of work, has complex dependencies
7 and differs a lot from distro to distro. All reasonable distros use udev these
8 days, the major ones make it mandatory and the system will not work without it.
10 The upstream udev project does not support or recomend to replace a distro's udev
11 installation with the upstream version. The installation of a unmodified upstream
12 version may render your system unusable! There is no "default" setup or a set
13 of "default" rules provided by the upstream udev version.
16 - 2.6 version of the Linux kernel
18 - the kernel must have sysfs, netlink, and hotplug enabled
20 - proc must be mounted on /proc
22 - sysfs must be mounted at /sys, no other location is supported
24 - udev creates and removes device nodes in /dev based on events
25 the kernel sends out on device discovery or removal
27 - during bootup /dev usually gets a tmpfs mounted which is populated scratch
28 by udev (created nodes don't survive a reboot, it always starts from scratch)
30 - udev replaces the hotplug event management invoked from /sbin/hotplug
31 by the udevd daemon, which receives the kernel events over netlink
33 - all kernel events are matched against a set of specified rules which
34 make it posible to hook into the event processing
36 - there is a copy of the rules files for all major distros in the etc/udev
37 directory (you may look there how others distros are doing it)
39 Setting which are used for building udev:
41 set this to the default root that you want to use
42 Only override this if you really know what you are doing
44 prefix for install target for package building
46 if set to 'true', udev will emit messages to the syslog when
47 it creates or removes device nodes. This is helpful to see
48 what udev is doing. This is enabled by default. Note, if you
49 are building udev against klibc it is recommended that you
50 disable this option (due to klibc's syslog implementation.)
52 if set to 'true', verbose debugging messages will be compiled into
53 the udev binaries. Default value is 'false'.
55 if set to 'true', udev will be built with SELinux support
56 enabled. This is disabled by default.
58 if set to 'true', udev is built and linked against the
59 included version of klibc. Default value is 'false'.
61 If this is not set it will default to /lib/modules/`uname -r`/build
62 This is used if USE_KLIBC=true to find the kernel include
63 directory that klibc needs to build against. This must be set
64 if you are not building udev while running a 2.6 kernel.
66 if set, will build the "extra" helper programs as specified
67 as listed (see below for an example.)
69 if you want to build udev using klibc with debugging messages:
70 make USE_KLIBC=true DEBUG=true
72 if you want to build the udev helper program cdrom_id and scsi_id:
73 make EXTRAS="extras/cdrom_id extras/scsi_id"
75 Please direct any comment/question/concern to the linux-hotplug-devel mailing list at:
76 linux-hotplug-devel@lists.sourceforge.net