X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=udev%2Fudev.xml;h=678023c373f444aef087447b9cf9619c0ba70cea;hb=e85f5ec15f1c0a820cc81b422c2fa157d9805896;hp=d2277c93d0d60e3b4b84ba3138237968ff9f5826;hpb=3f896a2abd76972eafe636cac4110608b6d3ff2f;p=elogind.git
diff --git a/udev/udev.xml b/udev/udev.xml
index d2277c93d..678023c37 100644
--- a/udev/udev.xml
+++ b/udev/udev.xml
@@ -18,23 +18,28 @@
udev
- dynamic device management
+ Linux dynamic device managementDESCRIPTION
- udev provides a dynamic device directory containing only the files for
- actually present devices. It creates or removes device node files in the
- /dev directory, or it renames network interfaces.
-
- Usually udev runs as udevd
- 8 and receives uevents directly from the
- kernel if a device is added or removed from the system.
-
- If udev receives a device event, it matches its configured rules
- against the available device attributes provided in sysfs to identify the device.
- Rules that match may provide additional device information or specify a device
- node name and multiple symlink names and instruct udev to run additional programs
- as part of the device event handling.
+ udev supplies the system software with device events, manages permissions
+ of device nodes and may create additional symlinks in the /dev
+ directory, or renames network interfaces. The kernel usually just assigns unpredictable
+ device names based on the order of discovery. Meaningful symlinks or network device
+ names provide a way to reliably identify devices based on their properties or
+ current configuration.
+
+ The udev daemon udevd
+ 8 receives device uevents directly from
+ the kernel whenever a device is added or removed from the system, or it changes its
+ state. When udev receives a device event, it matches its configured set of rules
+ against various device attributes to identify the device. Rules that match, may
+ provide additional device information to be stored in the udev database, or information
+ to be used to create meaningful symlink names.
+
+ All device information udev processes, is stored in the udev database and
+ sent out to possible event subscribers. Access to all stored data and the event
+ sources are provided by the library libudev.CONFIGURATION
@@ -84,9 +89,9 @@
If all match keys are matching against its value, the rule gets applied and the
assign keys get the specified value assigned.
- A matching rule may specify the name of the device node, add a symlink
- pointing to the node, or run a specified program as part of the event handling.
- If no matching rule is found, the default device node name is used.
+ A matching rule may rename a network interface, add symlinks
+ pointing to the device node, or run a specified program as part of
+ the event handling.A rule consists of a list of one or more key value pairs separated by
a comma. Each key has a distinct operation, depending on the used operator. Valid
@@ -304,13 +309,17 @@
- The name, a network interface should be renamed to, or the name
- a device node should be named. Usually the kernel provides the defined
- node name, or even creates and removes the node before udev receives
- any event. Changing the node name from the kernel's default may result
- in unexpected behavior and is not supported. Udev is only expected to
- handle device node permissions and to create additional symlinks, which
- do not conflict with the kernel device node names.
+ The name, a network interface should be renamed to. Or as
+ a temporary workaraound, the name a device node should be named.
+ Usually the kernel provides the defined node name, or even creates
+ and removes the node before udev even receives any event. Changing
+ the node name from the kernel's default creates inconsistencies
+ and is not supported. If the kernel and NAME specify different names,
+ an error will be logged. Udev is only expected to handle device node
+ permissions and to create additional symlinks, not to change
+ kernel-provided device node names. Instead of renaming a device node,
+ SYMLINK should be used. Symlink names must never conflict with
+ device node names, it will result in unpredictable behavior.
@@ -318,15 +327,15 @@
The name of a symlink targeting the node. Every matching rule will add
- this value to the list of symlinks to be created along with the device node.
- Multiple symlinks may be specified by separating the names by the space
- character. In case multiple devices claim the same name, the link will
- always point to the device with the highest link_priority. If the current device
- goes away, the links will be re-evaluated and the device with the next highest
- link_priority will own the link. If no link_priority is specified, the order
- of the devices, and which of them will own the link, is undefined. Claiming
- the same name for a node and links may result in unexpected behavior and is
- not supported.
+ this value to the list of symlinks to be created. Multiple symlinks may be
+ specified by separating the names by the space character. In case multiple
+ devices claim the same name, the link will always point to the device with
+ the highest link_priority. If the current device goes away, the links will
+ be re-evaluated and the device with the next highest link_priority will own
+ the link. If no link_priority is specified, the order of the devices, and
+ which one of them will own the link, is undefined. Claiming the same name for
+ a symlink, which is or might be used for a device node, may result in
+ unexpected behavior and is not supported.
@@ -379,18 +388,10 @@
is
specified, and the executed program returns non-zero, the event will be
marked as failed for a possible later handling.
- If no path is given, the program must be in
- /lib/udev, otherwise the full path must be
- specified.
- If the specified string starts with
- , all current event
- values will be passed to the specified socket, as a message in the same
- format the kernel sends an uevent. If the first character of the specified path
- is an @ character, an abstract namespace socket is used, instead of an existing
- socket file.
- Program name and arguments are separated with spaces. To
- include spaces in an argument, use single quotes. Please note
- that this does not run through a shell.
+ If no absolute path is given, the program is expected to live in
+ /lib/udev, otherwise the absolute path must be
+ specified. Program name and arguments are separated by spaces. Single quotes
+ can be used to specify arguments with spaces.