3.4 Option ROM Initialization flow

3.4 Option ROM Initialization Flow

The following outlines the typical steps used to initialize Option ROMs during a Plug and Play system BIOS POST:

Step 1 Initialize the boot device option ROMs.

This includes the Primary Input, Primary Output, and Initial Program Load (IPL) device option ROMs.

Step 2 Initialize ISA option ROMs by performing ISA ROM scan

The ISA ROM scan should be performed from C0000h to EFFFFh on every 2k boundary. Plug and Play option ROMs will not be included in the ROM scan.

Step 3 Initialize option ROMs for ISA devices which have a Plug and Play option ROM.

Typically, these devices will not provide support for dynamic configurability. However, the resources utilized by these devices can be obtained through the Static Resource Information Vector as described in section 3.2.

Step 4 Initialize option ROMs for Plug and Play cards which have a Plug and Play option ROM.

Step 5 Initialize option ROMs which support the Device Driver Initialization Model (DDIM).

Option ROMs which follow this model make the most efficient use of space consumed by option ROMs. Refer to Appendix B for more information on the DDIM.