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Diffstat (limited to 'src/udev/README')
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diff --git a/src/udev/README b/src/udev/README deleted file mode 100644 index 38459c6b22..0000000000 --- a/src/udev/README +++ /dev/null @@ -1,101 +0,0 @@ -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. - -Tools and rules shipped by udev are not public API and may change at any time. -Never call any private tool in /usr/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 /usr/lib/udev and the entire contents -of the /run/udev directory are private to udev and do change whenever needed. - -Requirements: - - Version 2.6.34 of the Linux kernel with sysfs, procfs, signalfd, inotify, - unix domain sockets, networking and hotplug enabled - - - Some architectures might need a later kernel, that supports accept4(), - or need to backport the accept4() syscall wiring in the kernel. - - - These options are required: - CONFIG_DEVTMPFS=y - CONFIG_HOTPLUG=y - CONFIG_INOTIFY_USER=y - CONFIG_NET=y - CONFIG_PROC_FS=y - CONFIG_SIGNALFD=y - CONFIG_SYSFS=y - CONFIG_SYSFS_DEPRECATED*=n - CONFIG_UEVENT_HELPER_PATH="" - - - These options might be needed: - CONFIG_BLK_DEV_BSG=y (SCSI devices) - CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes) - - - The /dev directory needs the 'devtmpfs' filesystem mounted. - Udev only manages the permissions and ownership of the - kernel-provided device nodes, and possibly creates additional symlinks. - - - Udev requires /run to be writable, which is usually done by mounting a - 'tmpfs' filesystem. - - - This version of udev does not work properly with the CONFIG_SYSFS_DEPRECATED* - option enabled. - - - 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 default rule sset requires 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. - - - Some udev extras have external dependencies like: - libglib2, usbutils, pciutils, and gperf. - All these extras can be disabled with configure options. - -Setup: - - The udev daemon should be started to handle device events sent by the kernel. - During bootup, the events for already existing devices can be replayed, so - that they are configured by udev. The systemd service files contain the - needed commands to start the udev daemon and the coldplug sequence. - - - Restarting the daemon never applies any rules to existing devices. - - - New/changed rule files are picked up automatically; there is usually no - daemon restart or signal needed. - -Operation: - - Based on events the kernel sends out on device creation/removal, udev - creates/removes device nodes and symlinks in the /dev directory. - - - All kernel events are matched against a set of specified rules, which - possibly hook into the event processing and load required kernel - modules to set up devices. For all devices, the kernel exports a major/minor - number; if needed, udev creates a device node with the default kernel - device 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 man pages: - http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev/ - -Please direct any comment/question to the linux-hotplug mailing list at: - linux-hotplug@vger.kernel.org |