-udev - Linux userspace device management
-
-Integrating udev in the system has complex dependencies and may differ from
-distribution to distribution. A system may not be able to boot up or work
-reliably without a properly installed udev version. The upstream udev project
-does not recommend replacing a distro's udev installation with the upstream
-version.
-
-The upstream udev project's set of default rules may require a most recent
-kernel release to work properly. This is currently version 2.6.31.
-
-Tools and rules shipped by udev are not public API and may change at any time.
-Never call any private tool in /lib/udev from any external application; it might
-just go away in the next release. Access to udev information is only offered
-by udevadm and libudev. Tools and rules in /lib/udev and the entire contents of
-the /dev/.udev directory are private to udev and do change whenever needed.
-
-Requirements:
- - Version 2.6.27 of the Linux kernel with sysfs, procfs, signalfd, inotify,
- unix domain sockets, networking and hotplug enabled:
- CONFIG_HOTPLUG=y
- CONFIG_UEVENT_HELPER_PATH=""
- CONFIG_NET=y
- CONFIG_UNIX=y
- CONFIG_SYSFS=y
- CONFIG_SYSFS_DEPRECATED*=n
- CONFIG_PROC_FS=y
- CONFIG_TMPFS=y
- CONFIG_INOTIFY_USER=y
- CONFIG_SIGNALFD=y
- CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
- CONFIG_BLK_DEV_BSG=y (SCSI devices)
-
- - Udev does not work with the CONFIG_SYSFS_DEPRECATED* option.
-
- - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
- but it is not supported.
-
- - The deprecated hotplug helper /sbin/hotplug should be disabled in the
- kernel configuration, it is not needed today, and may render the system
- unusable because the kernel may create too many processes in parallel
- so that the system runs out-of-memory.
-
- - The proc filesystem must be mounted on /proc, and the sysfs filesystem must
- be mounted at /sys. No other locations are supported by a standard
- udev installation.
-
- - The system must have the following group names resolvable at udev startup:
- disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, and kmem.
- Especially in LDAP setups, it is required that getgrnam() be able to resolve
- these group names with only the rootfs mounted and while no network is
- available.
-
- - The 'udev extras' has the following dependencies:
- libacl, libglib2, libusb, usbutils, pciutils, and gperf.
- These dependencies can be disabled with the --disable-extras configure option.
-
-Setup:
- - At bootup, the /dev directory should get the 'devtmpfs' filesystem
- mounted. Udev manages the permissions and ownership of the kernel-created
- device nodes, and udev possibly creates additional symlinks. If needed, udev also
- works on an empty 'tmpfs' filesystem, but some static device nodes like
- /dev/null, /dev/console, /dev/kmsg are needed to be able to start udev itself.
-
- - The udev daemon should be started to handle device events sent by the kernel.
- During bootup, the kernel can be asked to send events for all already existing
- devices so that they too can be configured by udev. This is usually done by:
- /sbin/udevadm trigger --type=subsystems
- /sbin/udevadm trigger --type=devices
-
- - Restarting the daemon never applies any rules to existing devices.
-
- - New/changed rule files are picked up automatically; there is no daemon
- restart or signal needed.
-
-Operation:
- - Udev creates/removes device nodes in /dev, based on events the kernel
- sends out on device creation/removal.
-
- - All kernel events are matched against a set of specified rules, which
- possibly hook into the event processing and load required kernel
- modules to setup devices. For all devices the kernel exports a major/minor
- number; if needed, udev creates a device node with the default kernel
- name. If specified, udev applies permissions/ownership to the device
- node, creates additional symlinks pointing to the node, and executes
- programs to handle the device.
-
- - The events udev handles, and the information udev merges into its device
- database, can be accessed with libudev:
- http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
- http://www.kernel.org/pub/linux/utils/kernel/hotplug/gudev/
-
-For more details about udev and udev rules see the udev(7) man page.
-
-Please direct any comment/question to the linux-hotplug mailing list at:
- linux-hotplug@vger.kernel.org
+systemd System and Service Manager
+
+DETAILS:
+ http://0pointer.de/blog/projects/systemd.html
+
+WEB SITE:
+ http://www.freedesktop.org/wiki/Software/systemd
+
+GIT:
+ git://anongit.freedesktop.org/systemd/systemd
+ ssh://git.freedesktop.org/git/systemd/systemd
+
+GITWEB:
+ http://cgit.freedesktop.org/systemd/systemd
+
+MAILING LIST:
+ http://lists.freedesktop.org/mailman/listinfo/systemd-devel
+ http://lists.freedesktop.org/mailman/listinfo/systemd-commits
+
+IRC:
+ #systemd on irc.freenode.org
+
+BUG REPORTS:
+ https://bugs.freedesktop.org/enter_bug.cgi?product=systemd
+
+AUTHOR:
+ Lennart Poettering
+ Kay Sievers
+ ...and many others
+
+LICENSE:
+ LGPLv2.1+ for all code
+ - except sd-daemon.[ch] and sd-readahead.[ch] which are MIT
+ - except src/udev/ which is GPLv2.0+
+
+REQUIREMENTS:
+ Linux kernel >= 2.6.39
+ with devtmpfs
+ with cgroups (but it's OK to disable all controllers)
+ optional but strongly recommended: autofs4, ipv6
+ dbus >= 1.4.0
+ libcap
+ libblkid >= 2.20 (from util-linux)
+ libkmod >= 5
+ PAM >= 1.1.2 (optional)
+ libcryptsetup (optional)
+ libgcrypt (optional)
+ libaudit (optional)
+ libacl (optional)
+ libattr (optional)
+ libselinux (optional)
+ liblzma (optional)
+ tcpwrappers (optional)
+ libgcrypt (optional)
+ libqrencode (optional)
+ libmicrohttpd (optional)
+
+ When you build from git you need the following additional dependencies:
+
+ docbook-xsl
+ xsltproc
+ automake
+ autoconf
+ libtool
+ intltool
+ gperf
+ gtkdocize (optional)
+ python (optional)
+ make, gcc, and similar tools
+
+ During runtime you need the following dependencies:
+
+ util-linux > v2.18 (requires fsck -l, agetty -s)
+ sulogin (from sysvinit-tools, optional but recommended)
+ dracut (optional)
+
+ When systemd-hostnamed is used it is strongly recommended to
+ install nss-myhostname to ensure that in a world of
+ dynamically changing hostnames the hostname stays resolveable
+ under all circumstances. In fact, systemd-hostnamed will warn
+ if nss-myhostname is not installed. Packagers are encouraged to
+ add a dependency on nss-myhostname to the package that
+ includes systemd-hostnamed.
+
+ Note that D-Bus can link against libsystemd-login.so, which
+ results in a cyclic build dependency. To accommodate for this
+ please build D-Bus without systemd first, then build systemd,
+ then rebuild D-Bus with systemd support.
+
+WARNINGS:
+ systemd will warn you during boot if /etc/mtab is not a
+ symlink to /proc/mounts. Please ensure that /etc/mtab is a
+ proper symlink.
+
+ systemd will warn you during boot if /usr is on a different
+ file system than /. While in systemd itself very little will
+ break if /usr is on a separate partition many of its
+ dependencies very likely will break sooner or later in one
+ form or another. For example udev rules tend to refer to
+ binaries in /usr, binaries that link to libraries in /usr or
+ binaries that refer to data files in /usr. Since these
+ breakages are not always directly visible systemd will warn
+ about this, since this kind of file system setup is not really
+ supported anymore by the basic set of Linux OS components.
+
+ For more information on this issue consult
+ http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
+
+ To run systemd under valgrind, compile with VALGRIND defined
+ (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
+ false positives will be triggered by code which violates
+ some rules but is actually safe.
+
+ENGINEERING AND CONSULTING SERVICES:
+ ProFUSION <http://profusion.mobi> offers professional
+ engineering and consulting services for systemd for embedded
+ and other use. Please contact Gustavo Barbieri
+ <barbieri@profusion.mobi> for more information.
+
+ Disclaimer: This notice is not a recommendation or official
+ endorsement. However, ProFUSION's upstream work has been very
+ beneficial for the systemd project.
~ianmdlvl / elogind.git / blobdiff