X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=a14e5c0fcff04e40b81ab462d236aa12d99fab8e;hp=2cde586ce23ddcc0ec15cc0b653cf6b7fb18d240;hb=9060b066d9e7aaca9795010ac5fff61018947f87;hpb=01618658fd82dbc5e6315b639f00e87c6fee3c54 diff --git a/README b/README index 2cde586ce..a14e5c0fc 100644 --- a/README +++ b/README @@ -9,37 +9,40 @@ Important Note: recommend to replace a distro's udev installation with the upstream version. Requirements: - - 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. + - Version 2.6.25 of the Linux kernel with sysfs, procfs, signalfd, inotify, + unix domain sockets, networking and hotplug 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 does not make any sense - don't complain if anything goes wrong.) + - For reliable operation, the kernel must not use the CONFIG_SYSFS_DEPRECATED* + option. + + - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module is not + supported. - The proc filesystem must be mounted on /proc/, the sysfs filesystem must be mounted at /sys/. No other locations are supported by udev. + - The system must have the following group names resolvable at udev startup: + disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem. + Especially in LDAP setups, it is required, that getgrnam() is able to resolve + these group names with only the rootfs mounted, and while no network is + available. Operation: Udev creates and removes device nodes in /dev/, based on events the kernel sends out on device discovery or removal. - - 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. + - Early in the boot process, the /dev/ directory should get a 'tmpfs' + filesystem mounted, which is maintained by udev. Created nodes or changed + permissions will not survive a reboot, which is intentional. - The content of /lib/udev/devices/ directory which contains the nodes, symlinks and directories, which are always expected to be in /dev, should be copied over to the tmpfs mounted /dev, to provide the required nodes to initialize udev and continue booting. - - 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. - - - The udevd daemon must be started on bootup to receive netlink uevents - from the kernel driver core. + - The old hotplug helper /sbin/hotplug should be disabled in the kernel + configuration, it is not needed, and may render the system unusable + because of a fork-bombing behavior. - All kernel events are matched against a set of specified rules in /lib/udev/rules.d/ which make it possible to hook into the event