mirror of
https://github.com/systemd/systemd.git
synced 2024-12-25 01:34:28 +03:00
update README and NEWS
This commit is contained in:
parent
26420abf54
commit
eea1fd84f0
1
NEWS
1
NEWS
@ -1,5 +1,6 @@
|
|||||||
udev 151
|
udev 151
|
||||||
========
|
========
|
||||||
|
Bugfixes.
|
||||||
|
|
||||||
udev 150
|
udev 150
|
||||||
========
|
========
|
||||||
|
87
README
87
README
@ -1,9 +1,13 @@
|
|||||||
udev - userspace device management
|
udev - Linux userspace device management
|
||||||
|
|
||||||
Integrating udev in the system has complex dependencies and differs from distro
|
Integrating udev in the system has complex dependencies and may differ from
|
||||||
to distro. All major distros depend on udev these days and the system may not
|
distribution to distribution. A system may not be able to boot up or work
|
||||||
work without a properly installed version. The upstream udev project does not
|
reliably without a properly installed udev version. The upstream udev project
|
||||||
recommend to replace a distro's udev installation with the upstream version.
|
does not recommend to replace 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.
|
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
|
Never call any private tool in /lib/udev from any external application, it might
|
||||||
@ -27,14 +31,19 @@ Requirements:
|
|||||||
CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
|
CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
|
||||||
CONFIG_BLK_DEV_BSG=y (SCSI devices)
|
CONFIG_BLK_DEV_BSG=y (SCSI devices)
|
||||||
|
|
||||||
- For reliable operations, the kernel must not use the CONFIG_SYSFS_DEPRECATED*
|
- Udev will not work with the CONFIG_SYSFS_DEPRECATED* option.
|
||||||
option.
|
|
||||||
|
|
||||||
- Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
|
- Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
|
||||||
but it is not supported.
|
but it is not supported.
|
||||||
|
|
||||||
|
- 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, the sysfs filesystem must
|
- The proc filesystem must be mounted on /proc, the sysfs filesystem must
|
||||||
be mounted at /sys. No other locations are supported by udev.
|
be mounted at /sys. No other locations are supported by a standard
|
||||||
|
udev installation.
|
||||||
|
|
||||||
- The system must have the following group names resolvable at udev startup:
|
- The system must have the following group names resolvable at udev startup:
|
||||||
disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
|
disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
|
||||||
@ -42,35 +51,51 @@ Requirements:
|
|||||||
these group names with only the rootfs mounted, and while no network is
|
these group names with only the rootfs mounted, and while no network is
|
||||||
available.
|
available.
|
||||||
|
|
||||||
- To build all udev extras, libacl, libglib2, libusb, usbutils, pciutils,
|
- To build all 'udev extras', libacl, libglib2, libusb, usbutils, pciutils,
|
||||||
gperf are needed. These dependencies can be disabled with the
|
gperf are needed. These dependencies can be disabled with the
|
||||||
--disable-extras option.
|
--disable-extras configure option.
|
||||||
|
|
||||||
|
Setup:
|
||||||
|
- At bootup, the /dev directory should get the 'devtmpfs' filesystem
|
||||||
|
mounted. Udev will manage permissions and ownership of the kernel-created
|
||||||
|
device nodes, and possibly create 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.
|
||||||
|
|
||||||
|
- The content of /lib/udev/devices directory which contains static content like
|
||||||
|
symlinks and directories, which are always expected to be in /dev, should
|
||||||
|
be copied over to the mounted /dev directory:
|
||||||
|
cp -axT --remove-destination /lib/udev/devices /dev
|
||||||
|
|
||||||
|
- 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, to apply the configuration to these devices. This is usually done by:
|
||||||
|
/sbin/udevadm trigger --type=subsystems
|
||||||
|
/sbin/udevadm trigger --type=devices
|
||||||
|
|
||||||
|
- Restarting the daemon does never apply any rules to existing devices.
|
||||||
|
|
||||||
|
- New/changed rule files are picked up automatically, there is no daemon
|
||||||
|
restart or signal needed.
|
||||||
|
|
||||||
Operation:
|
Operation:
|
||||||
Udev creates and removes device nodes in /dev, based on events the kernel
|
- Udev creates/removes device nodes in /dev, based on events the kernel
|
||||||
sends out on device discovery or removal.
|
sends out on device creation/removal.
|
||||||
|
|
||||||
- Early in the boot process, the /dev directory should get a 'tmpfs'
|
- All kernel events are matched against a set of specified rules, which
|
||||||
filesystem mounted, which is maintained by udev. Created nodes or changed
|
possibly hook into the event processing and load required kernel
|
||||||
permissions will not survive a reboot, which is intentional.
|
modules to setup devices. For all devices the kernel exports a major/minor
|
||||||
|
number, if needed, udev will create a device node with the default kernel
|
||||||
|
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 content of /lib/udev/devices directory which contains the nodes,
|
- The events udev handles, and the information udev merges into its device
|
||||||
symlinks and directories, which are always expected to be in /dev, should
|
database, can be accessed with libudev:
|
||||||
be copied over to the tmpfs mounted /dev, to provide the required nodes
|
http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/
|
||||||
to initialize udev and continue booting.
|
http://www.kernel.org/pub/linux/utils/kernel/hotplug/gudev/
|
||||||
|
|
||||||
- The deprecated hotplug helper /sbin/hotplug should be disabled in the
|
For more details about udev and udev rules see the udev(7) man page.
|
||||||
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.
|
|
||||||
|
|
||||||
- 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
|
|
||||||
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
|
|
||||||
matching udev rule.
|
|
||||||
|
|
||||||
Please direct any comment/question to the linux-hotplug mailing list at:
|
Please direct any comment/question to the linux-hotplug mailing list at:
|
||||||
linux-hotplug@vger.kernel.org
|
linux-hotplug@vger.kernel.org
|
||||||
|
|
||||||
|
Loading…
Reference in New Issue
Block a user