X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=00acf97c27e5405b5974a4c373b80f8113e17767;hp=7ac1d4509ccfbed7877e9efb2d3140d76da032d9;hb=41677cf51fb2c14aa512ecf9410e43eb35560408;hpb=cad4697469883b73cdd43e7e83db122951535ee8 diff --git a/README b/README index 7ac1d4509..00acf97c2 100644 --- a/README +++ b/README @@ -3,34 +3,29 @@ 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 major distros depend on udev these - days and the system may not work without a proper installed version. 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. Until now, there is no "default" setup or a set of - "default" rules provided by the upstream udev version. + Integrating udev in the system has complex dependencies and differs from distro + to distro. All major distros depend on udev these days and the system may not + work without a properly installed version. The upstream udev project does not + recommend to replace a distro's udev installation with the upstream version. Requirements: - - 2.6.x version of the Linux kernel. See the RELEASE-NOTES file in the - udev tree and the Documentation/Changes in the kernel source tree for - the actual dependency. + - Version 2.6.18 of the Linux kernel for reliable operation of this release of + udev. The kernel may have a requirement on udev too, see Documentation/Changes + in the kernel source tree for the actual dependency. - - The kernel must have sysfs and unix domain socket enabled. + - The kernel must have sysfs, unix domain sockets and networking enabled. (unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work, - but it is completely silly - don't complain if anything goes wrong.) + but it does not make any sense - don't complain if anything goes wrong.) - - The proc filesystem must be mounted on /proc. - - - The sysfs filesystem must be mounted at /sys. No other location - will be supported by udev. + - The proc filesystem must be mounted on /proc, the sysfs filesystem must + be mounted at /sys. No other locations are supported by udev. Operation: Udev creates and removes device nodes in /dev, based on events the kernel sends out on device discovery or removal. - - Early in the boot process, the /dev directory should get a tmpfs + - Very early in the boot process, the /dev directory should get a 'tmpfs' filesystem mounted, which is populated from scratch by udev. Created nodes or changed permissions will not survive a reboot, which is intentional. @@ -39,18 +34,18 @@ Operation: be copied over to the tmpfs mounted /dev, to provide the required nodes to initialize udev and continue booting. - - The udevd daemon must be started by an init script to receive netlink - uevents from the kernel driver core. + - The old hotplug helper /sbin/hotplug should be disabled on bootup, before + actions like loading kernel modules are taken, which may cause a lot of + events. - - From kernel version 2.6.15 on, the hotplug helper /sbin/hotplug should - be disabled with an init script before actions like loading kernel - modules are taken, which may cause a lot of events. + - The udevd daemon must be started on bootup to receive netlink uevents + from the kernel driver core. - All kernel events are matched against a set of specified rules in /etc/udev/rules.d/ which make it possible to hook into the event processing to load required kernel modules and setup devices. For all devices the kernel exports a major/minor number, udev will create a - device node with the default kernel name or the one specified by a + device node with the default kernel name, or the one specified by a matching udev rule. @@ -69,10 +64,6 @@ Compile Options: 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 list of helper programs in extras/ to build. make EXTRAS="extras/cdrom_id extras/scsi_id extras/volume_id" @@ -80,24 +71,21 @@ Compile Options: Installation: - The install target intalls the udev binaries in the default locations, - All at boot time reqired binaries will be installed in /lib/udev or /sbin. + All binaries will be installed in /lib/udev or /sbin. - The default location for scripts and binaries that are called from - rules is /lib/udev. Other packages who install udev rules, should use + rules is /lib/udev. Other packages who install udev rules, may use that directory too. - - It is recommended to use the /lib/udev/devices directory to place + - 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. - - Copies of the rules files for the major distros are provided as examples - in the etc/udev directory. - - - The persistent device naming links in /dev/disk/ are required by other - software that depends on the data udev has collected from the devices + - Default udev rules and persistent device naming rules are required by other + software that depends on the data udev collects from the devices, and should be installed by default with every udev installation. Please direct any comment/question/concern to the linux-hotplug-devel mailing list at: - linux-hotplug-devel@lists.sourceforge.net + linux-hotplug@vger.kernel.org