provides reference information needed to write
device drivers for Solaris 2.x. It describes the
interfaces provided by the
Device Driver Interface Driver-Kernel Interface (DDI/DKI).
Drivers that conform to this specification are
more likely to work in future releases and may be portable to other
Software is usually considered portable if it can be adapted to run in a different environment more cheaply than it can be rewritten. The new environment may include a different processor, operating system, and even the language in which the program is written, if a language translator is available. Likewise the new environment might include multiple processors. More often, however, software is ported between environments that share an operating system, processor, and source language. The source code is modified to accommodate the differences in compilers or processors or releases of the operating system.
In the past, device drivers did not port easily for one or more of the following reasons:
Operating systems are periodically reissued to customers as a way to improve performance, fix bugs, and add new features. This is probably the most common threat to compatibility encountered by developers responsible for maintaining software. Another common problem is upgrading hardware. As new hardware is developed, customers occasionally decide to upgrade to faster, more capable computers of the same family. Although they may run the same operating system as those being replaced, architecture-specific code may prevent the software from porting.
Although application programs have all of the porting problems mentioned, developers attempting to port device drivers have special challenges. Before describing the DDI/DKI, it is necessary to understand the position of device drivers in operating systems.
Device drivers are kernel modules that control data transferred to and received from peripheral devices but are developed independently from the rest of the kernel. If the goal of achieving complete freedom in modifying the kernel is to be reconciled with the goal of binary compatibility with existing drivers, the interaction between drivers and the kernel must be rigorously regulated. This driver/kernel service interface is the most important of the three distinguishable interfaces for a driver, summarized as follows:
The primary goal of the DDI/DKI is to facilitate both source and binary portability across successive releases of the operating systems on a particular machine. In addition, it promotes source portability across implementations of UNIX on different machines, and applies only to implementations based on System V Release 4. The DDI/DKI consists of several sections:
To achieve the goal of source and binary compatibility, the functions, routines, and structures specified in the DDI/DKI must be used according to these rules.
Section 9 is for software engineers responsible for creating, modifying, or maintaining drivers that run on this operating system and beyond. It assumes that the reader is familiar with system internals and the C Programming Language.
Section 9 is divided into three subsections:
SunSoft's implementation of the DDI/DKI was designed to provide binary compatibility for third-party device drivers across currently supported hardware platforms across minor releases of the operating system.
However, unforeseen technical issues may force changes to the binary interface of the DDI/DKI. We cannot therefore promise or in any way assure that DDI/DKI-compliant device drivers will continue to operate correctly on future releases.
Furthermore, future releases may contain additions to the DDI/DKI to support future platforms. At that time device drivers wishing to operate across the new set of supported platforms may require these additions.
Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97