Intel Extensible Firmware Interface - Manual (Page 509)

Protocols — PCI Bus Support
Version 1.10 12/01/02 12-91
Description
The GetBarAttributes() function returns in Supports the mask of attributes that the PCI
controller supports setting for the BAR specified by BarIndex . It also returns in Resources a
list of ACPI 2.0 resource descriptors for the BAR specified by BarIndex . Both Supports and
Resources are optional parameters. If both Supports and Resources are NULL , then
EFI_INVALID_PARAMETER is returned. It is the caller’s responsibility to free Resources
with the Boot Service FreePool() when the caller is done with the contents of Resources . If
there are not enough resources to allocate Resources , then EFI_OUT_OF_RESOURCES is
returned.
If a bit is set in Supports , then the PCI controller supports this attribute type for the BAR
specified by BarIndex , and a call can be made to SetBarAttributes() using that
attribute type.
Status Codes Returned
EFI_SUCCESS If Supports is not NULL , then the attributes that the PCI
controller supports are returned in Supports . If Resources
is not NULL , then the ACPI 2.0 resource descriptors that the PCI
controller is currently using are returned in Resources .
EFI_OUT_OF_RESOURCES There are not enough resources available to allocate
Resources .
EFI_UNSUPPORTED BarIndex not valid for this PCI controller.
EFI_INVALID_PARAMETER Both Supports and Attributes are NULL .