Initialization

Initialization

A central component of the DOS-EISA world is a configuration program that allocates and sets up the resources that the EISA card uses. Once this program runs, the configuration results are downloaded into non-volatile memory for future driver use. Storing the configuration results serves two purposes:

The stored results make it easy for drivers to operate as boot devices because the drivers can initialize in a standalone environment, in which the operating system is not up and able to allocate resources to the driver. But, because the Silicon Graphics EISA environment does not now support booting from EISA devices, saving the resource allocation information in nonvolatile RAM is superfluous.

DOS saves the configuration file to store a set of card register programmatic instructions that initialize various I/O ports. This is useful when writing a generic device driver that must control boards that have different initialization registers but are basically the same, even though they come from different manufacturers.
Note: Although Silicon Graphics does not support this functionality, it should not cause any problems because you can write the driver initialization routine to check the product ID and execute the appropriate initialization code. Be sure to consider the byte order when checking the product ID.

In the DOS environment, the EISA configuration program allocates memory spaces, DMA channels, and interrupt request lines. In IRIX release 5.x, lboot handles the allocation of memory and I/O spaces. lboot passes the allocation results to the driver via the edt_t structure. Memory and I/O spaces are passed via edt, but dynamic resources are not. The driver requests DMA channels and interrupt request lines or queues (IRQs) as dynamic resources as required.