4.3 Plug and Play BIOS Functions

The following subsections describe the Plug and Play BIOS interface. The function return values are listed in Appendix C. The Plug and Play BIOS functions will preserve all FLAGS and registers except for the AX register, which will contain the return code. The BIOS functions will use the caller's stack and a minimum of 1024 bytes of stack space must be available to these functions. It is important to note that system BIOS function(s) used to set the configuration of a systemboard device will not validate the configuration information passed by the caller and may not return an error code.

Option ROM initialization routines can not depend on any of the Plug and Play runtime functions to be available until after INT19 has been invoked at the end of the POST process.