Background

Background

Before you upgrade a perfectly good device driver that runs on an older version of IRIX, compute the time it will take to rewrite your driver to run under the new operating systems against the actual performance improvement you hope to achieve. In some cases, it may be to your advantage to continue using an older driver by recompiling its source code under the new operating system. For those cases where it is to your advantage to modify an existing driver, the following notes are provided.

IRIX 5.x

IRIX 5.x is a binary-compatible upgrade to IRIX 4.0.x at the user program level. However, due to the extensive internal changes to the IRIX kernel, device drivers and other kernel components, such as STREAMS modules and file systems, must be revised and recompiled for the IRIX 5.x environment. It is possible that changes to IRIX 5.3 will become effective after the publication of this manual.

Most of the changes in the IRIX kernel result from supporting the SVR4 interfaces for both applications programs and for certain kernel internal interfaces. The IRIX 5.x kernel interfaces are:

SVR4 Device Driver Interface/Driver Kernel Interface (SVR4 DDI/DKI) described in the IRIX Device Driver Reference Pages. The IRIX 5.x operating system implementation uses a multiprocessor version of DDI/DKI developed for Silicon Graphics platforms.
SVR4 STREAMS Interface, which is documented in the UNIX® System V Release 4 STREAMS Programming Guide.
IRIX 5.x Data Link Provider Interface (DLPI) (relevant to STREAMS protocol stacks and to network drivers). This standard interface, defined by IEEE Standard 802.3, permits flexible integration protocol stacks and their "peaceful coexistence" with the TCP/IP stack. Protocol stacks register themselves with DLPI, as do the network drivers present in the system. The new protocol stack is thus isolated from the specific network hardware support present in the system.

IRIX 6.0

IRIX 6.0 is the 64-bit operating system for all Silicon Graphics systems that use MIPS R8000 series microprocessors. Because the IRIX 6.0 kernel is itself a 64-bit object, device drivers must be ported to the 64-bit operating system.