Appendix J: Oem Kernel Generation For The Iris Workstation - Silicon Graphics IRIS Workstation User Manual

Appendix J: OEM Kernel Generation for the IRIS
Workstation
J.1 Introduction
The purpose of this document is to describe the method for generating a kernel
which includes OEM device drivers. Towards this goal, some of the
differences between the Silicon Graphics System V and the standard System V
implementations will be discussed. However, this document does not attempt
to teach device driver writing.
J.2 Device Drivers
Changes in the device driver interface occur in several areas: device addressing,
interrupt levels, the physical (raw) I/O interface and the addition of the auto-
configuration process. Only the modifications to the physical I/O interface will
be discussed here. Refer to the document Building 4.2BSD UNIX Systems with
Config for a discussion of the auto-configuration additions.
Device Addressing
All devices are addressed through the Multibus I/O space. The OEM customer
is restricted to the Multibus addresses within the range: 0xF000 to 0xFFFF.
Silicon Graphics has reserved the remainder of the Multibus I/O space for its
own use. The constant MBIOBASE, defined in ../pmII/cpureg.h, is used as the
base address for the Multibus I/O space. The actual device address, in the
kernel virtual space, is the sum of the MBIOBASE constant and the device's
assigned Multibus I/O address.
A second restriction for OEM Multibus devices is that they decode full 16-bit
I/O addresses. Older 8-bit decoding I/O devices will not function correctly.
They may also damage themselves and any other device on the bus. This
damage can also occur when configuring two devices at the same address. It is
strongly recommended that you verify your device addresses to make sure it is
within the allowed address range.
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