Writing Device Drivers

Bus Architectures

This section describes a number of bus-specific topics including device identification, device addressing, and interrupts.

Device Identification

Device identification is the process of determining which devices are present in the system.

Self-Identifying Devices

Some devices are self-identifying--the device itself provides information to the system so that it can identify the device driver that needs to be used. The device usually provides additional information to the system in the form of name-value (name=value) pairs that can be retrieved using the property interfaces. See "Properties" for more information on properties.

SBus and PCI local bus devices are examples of self-identifying devices. On SBus, the information is usually derived from a small Forth program stored in the FCode PROM on the device. PCI devices provide a configuration space containing device configuration information. See sbus(4) and pci(4) for more information.

Non-Self-Identifying Devices

Devices that do not provide information to the system to identify themselves are called non-self-identifying devices. Drivers for these devices must have a probe(9E) routine that determines whether the device is really present. In addition, information about the device must be provided in a hardware configuration file (see driver.conf(4)), so that the system can provide probe(9E) with the information it needs to contact the device. See probe(9E) for more information.

A VMEbus device is an example of a non-self-identifying device. See vme(4) for more information.


The SunOS system supports polling interrupts and vectored interrupts.The Solaris 7 DDI/DKI interrupt model is the same for both. See "Types of Interrupts" for more information about interrupt handling.