| SUSE LINUX Documentation Chapter 32. The Hotplug System / 32.3. Hotplug Device Configuration | ||||
|---|---|---|---|---|
 | 32.2. Hotplug Events | 32.4. Automatic Module Loading |  | |
| SUSE LINUX Documentation Chapter 32. The Hotplug System / 32.3. Hotplug Device Configuration | ||||
|---|---|---|---|---|
| 32.2. Hotplug Events | 32.4. Automatic Module Loading | | |
Hotplug agents have been deprecated as of SUSE Linux 10.0. All device configuration should now be done via udev rules. udev provides a compability rule to call existing custom agents. However, converting custom agents into udev rules should be considered.
A hotplug agent is an executable program that performs suitable
actions for an event. The agents for device events are located in
/etc/hotplug.d/event name
and /etc/hotplug.d/default. All programs in these
directories that have the suffix .hotplug are executed
in alphabetical order.
To facilitate device configuration it is usually sufficient to load
a kernel module. In some cases, additional commands need
to be called for a proper device configuration.
In SUSE Linux, this is handled generally by udev rules. However, if a
custom device
configuration is required, the device
configuration is done by /sbin/hwup or
/sbin/hwdown. These programs search for a
configuration suitable for the device in the directory
/etc/sysconfig/hardware and apply it. For example, to
prevent a specific device from being initialized, create a
configuration
file with an appropriate name and set the start mode to
manual or off. If
/sbin/hwup does not find any configuration, it
looks for the environment variable MODALIAS. If
it exists, modprobe automatically loads
the corresponding module. The MODALIAS variable
is automatically generated by kernel hotplug events for devices
that require a module to be loaded. For more information, see
Section 32.4, “Automatic Module Loading”.
More information about
/sbin/hwup is available in the file
/usr/share/doc/packages/sysconfig/README and
in the manual page man hwup.
Before interface agents are called, udev usually generates a device node the system can access. udev enables the assignment of persistent names to interfaces. See Chapter 33, Dynamic Device Nodes with udev for details. The interfaces itself are then set up according to the respective udev rules. The procedures for some interfaces are described below.
Network interfaces are initialized with
/sbin/ifup and deactivated with
/sbin/ifdown. Details are provided
in the file /usr/share/doc/packages/sysconfig/README
and in the ifup man page.
If a computer has several network devices with different drivers, the designations of the interface can change if another driver is loaded faster while the system is booting. SUSE Linux tries to keep the numbering persistent—the devices retain the interface name they have been assigned during configuration. This assigment is done via udev rules. To change the assignment later, the udev rules must be changed.
The best solution, however, is to use persistent interface
designations. You can specify the names of the individual interfaces in the
configuration files. Details about this method are available
in the file /usr/share/doc/packages/sysconfig/README.
Since SUSE Linux 9.3, udev also deals with network interfaces,
although these are not
device nodes. This allows use of persistent interface names in a more
standardized manner.
Interfaces to storage devices must be mounted
to be able to access them. This can be fully automated
or preconfigured. Additionally, SUSE Linux distinguishes between
system and user devices. System devices can only be automatically
mounted by creating an entry in /etc/fstab.
User devices are handled via hal by default.
If a different configuration for user devices is required, these
devices can be entered into /etc/fstab.
Alternatively, the handling of this device in hal
can be modified. For more information about hal, refer
to /usr/share/doc/packages/hal/hal-spec.html.
The use of persistent device names is recommended, because traditional device names may change depending on the initialization sequence. Details about persistent device names is available in Chapter 33, Dynamic Device Nodes with udev.
