Configuring HP-UX For Peripherals

Chapter 1 21

Getting Started

Understanding Loadable Device Drivers

As of HP-UX Release 11.0, a new feature known as Dynamically

Loadable Kernel Module (DLKM) provides the means to add a device

driver to a running UNIX system without rebooting the system or

rebuilding the kernel. This feature also makes it possible to dynamically

remove a device driver from the UNIX system when the driver is no

longer needed, thereby freeing system resources for other use.

The DLKM feature not only provides the infrastructure to load drivers

into a running kernel, but it also allows a driver to be statically linked

into the kernel—the way all drivers were included in the kernel prior to

HP-UX 11.0. Simply setting a ﬂag in one of the driver’s conﬁguration

ﬁles determines whether a driver is to be conﬁgured as dynamically

loadable or statically linked.

For HP-UX 11.0, the system must be in a run-time state before dynamic

module loading is available. Thus, drivers required during system boot

must be conﬁgured as statically linked.

DLKM Module Types

The DLKM feature currently supports the following types of drivers:

WSIO class drivers, WSIO interface drivers, and STREAMS drivers. It

also supports STREAMS modules and miscellaneous modules. An

example of a miscellaneous module is a module containing support

functions not required in the statically conﬁgured kernel but shared

among multiple loadable modules.

New Module Packaging

As of HP-UX 11.0, each driver may have its own master and system

ﬁles, whereas prior to HP-UX 11.0, the driver shared master ﬁles and

had access to a single system ﬁle—the HP-UX system ﬁle

(/stand/system by default). (The HP-UX system ﬁle is still supported in

HP-UX 11.0.) This new way of packaging drivers together with the new

way of writing driver source code is what makes the DLKM feature

possible.

NOTE See the master (4) manpage for descriptions of the two kinds of master