Intel Extensible Firmware Interface - Manual (Page 458)

Extensible Firmware Interface Specification
12-40 12/01/02 Version 1.10
EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Configuration()
Summary
Retrieves the current resource settings of this PCI root bridge in the form of a set of ACPI 2.0
resource descriptors.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_CONFIGURATION) (
IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL
*This,
OUT VOID **Resources
);
Parameters
This A pointer to the EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL .
Type EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL is defined in
Section 12.2.
Resources A pointer to the ACPI 2.0 resource descriptors that describe the
current configuration of this PCI root bridge. The storage for the
ACPI 2.0 resource descriptors is allocated by this function. The
caller must treat the return buffer as read-only data, and the buffer
must not be freed by the caller. See “Related Definitions” for the
ACPI 2.0 resource descriptors that may be used.
Related Definitions
There are only two resource descriptor types from the ACPI Specification that may be used to
describe the current resources allocated to a PCI root bridge. These are the QWORD Address
Space Descriptor (ACPI 2.0 Section 6.4.3.5.1), and the End Tag (ACPI 2.0 Section 6.4.2.8). The
QWORD Address Space Descriptor can describe memory, I/O, and bus number ranges for dynamic
or fixed resources. The configuration of a PCI root bridge is described with one or more QWORD
Address Space Descriptors followed by an End Tag. Table 12-2 and Table 12-3 contains these two
descriptor types. Please see the ACPI Specification for details on the field values.