X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=0d25b84fad9f2c604ad83271c51572e49b6c7eb2;hp=148217d16a3e1b9f59e2612e5df053aa4669ab85;hb=636c7a44d5143fdca298cb9087a529aa1d71c431;hpb=e3c14a7ff3931e4c09711966e3a82fd8f98e568a diff --git a/README b/README index 148217d16..0d25b84fa 100644 --- a/README +++ b/README @@ -10,10 +10,10 @@ The upstream udev project's set of default rules may require a most recent kernel release to work properly. This is currently version 2.6.32. 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. +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, @@ -59,21 +59,21 @@ Requirements: available. - Some udev extras have external dependencies like: - libacl, libglib2, libusb, usbutils, pciutils, and gperf. + libacl, libglib2, usbutils, pciutils, and gperf. All these extras can be disabled with configure options. 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. + works on an empty 'tmpfs' filesystem, but some device nodes like + /dev/null, /dev/console, /dev/kmsg should be created before udevd is started. - 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 + During bootup, the events for already existing devices can be replayed, so + that they are configured by udev. This is usually done by: + udevadm trigger --action=add --type=subsystems + udevadm trigger --action=add --type=devices - Restarting the daemon never applies any rules to existing devices. @@ -82,13 +82,13 @@ Setup: Operation: - Based on events the kernel sends out on device creation/removal, udev - creates/removes device nodes in the /dev directory. + 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 - name. If specified, udev applies permissions/ownership to the device + 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.