Taking Control of Devices

Taking Control of Devices

When your program needs direct control of a device, you have the following choices:

If it is a device for which IRIX or the device manufacturer distributes a device driver, find the device driver reference page in volume 7 to learn the device driver's support for read(), write(), mmap(), and ioctl(). Use these functions to control the device.
If it is a VME device without bus master capability, you can control it directly from your program using programmed I/O or user-initiated DMA. Both options are discussed under "The VME Bus".
If it is a VME device with bus master (on-board DMA) capability, you should receive an IRIX device driver from the OEM. Consult IRIX Admin: System Configuration and Operation to install the device and its driver. Read the OEM reference page to learn the device driver's support for read(), write(), and ioctl().
If it is a SCSI device that does not have built-in IRIX support, you can control it from your own program using the generic SCSI device driver. See "Generic SCSI Device Driver".

In the remaining case, you have a device with no driver. In this case you must create a device driver. This process is documented in the IRIX Device Driver Programmer's Guide, which contains extensive information and sample code (see "Other Useful Books" on page xxiii).