Plug and Play BIOS Specification

Plug and Play BIOS Specification 1.0A Page 47
4.7.2 Function 0Ah - Get Statically Allocated Resource Information
Synopsis:
int FAR (*entryPoint)(Function, ResourceBlock, BiosSelector);
int Function; /* PnP BIOS Function 0Ah */
unsigned char FAR *ResourceBlock; /* Block of resources statically allocated to devices */
unsigned int BiosSelector; /* PnP BIOS readable/writable selector */
Description:
Optional. This function will return the system resources that are being utilized by the legacy ISA devices
that are installed in the system. These system resources are the resources that have been reported to the
system BIOS through the Set Allocated ISA Resource Info function. The resources allocated to the legacy
ISA devices in the system are reported in the ResourceBlock parameter. It is important to note that the
information returned represents the resource usage rounded up to the nearest granularity range supported
by the system BIOS and not the actual resources used by the legacy ISA devices in the system. It is
recommended that the system software keep track of the system resources used by legacy ISA cards in
order to account for the exact system resources usage of the legacy ISA cards installed in the system. The
format of the data contained in the block follows the format defined in the Plug and Play ISA
Specification under the section labeled Plug and Play Resources. This data is provided as a series of data
structures with each structure having a unique tag or identifier. The ResourceBlock must be a minimum
of 2 Kbytes to ensure that there is adequate space for the system BIOS to return the legacy ISA resource
information.
The BiosSelector parameter enables the system BIOS, if necessary, to update system variables that are
contained in the system BIOS memory space. If this function is called from protected mode the caller
must create a data segment descriptor using the 16-bit Protected Mode data segment base address
specified in the Plug and Play Installation Check data structure, a limit of 64k, and the descriptor must be
read/write capable. If this function is called from real mode, BiosSelector should be set to the Real Mode
16-bit data segment address as specified in the Plug and Play Installation Check structure. Refer to
section 4.4 above for more information on the Plug and Play Installation Check Structure and the
elements that make up the structure.
If this function returns USE_ESCD_SUPPORT, then accessing the information describing the resources
allocated to devices to the system BIOS must be handled through the interface defined by the ESCD
Specification. Refer to the ESCD Specification for a complete description of the interfaces to support the
ESCD as well as the format of the ESCD.
This function is available in real mode and 16-bit protected mode.
Returns:
0 if successful - SUCCESS
!0 if an error (Bit 7 set) or a warning occurred or no pending events - error code (The function return
codes are described in Appendix C)
The FLAGS and registers will be preserved, except for AX which contains the return code.