7.2.4 Adding Driver Family Override Protocol Feature

The EFI_DRIVER_FAMILY_OVERRIDE_PROTOCOL is optional. It is typically produced by UEFI Drivers associated with a set of similar controllers where multiple versions of a UEFI Driver for the set of similar controllers may be simultaneously present in a platform. This protocol allows each UEFI Driver to advertise a version number such that the UEFI Driver with the highest version is selected to manage all the controllers in the set of similar controllers.

PCI Use Case: If a platform has 3 PCI SCSI adapters from the same manufacturer, and the manufacturer requires the PCI SCSI adapter having the highest version UEFI Driver to manage all 3 PCI SCSI adapters, the Driver Family Override Protocol is required and provides the version value used to make the selection. If the Driver Family Override Protocol is not produced, the Bus Specific Driver Override Protocol for PCI selects the UEFI Driver from the adapter's PCI Option ROM to manage each adapter.

There are no EDK II library functions to help install the Driver Family Override Protocol. Instead, the UEFI Driver requiring this feature must install the Driver Family Override Protocol using the UEFI Boot Service InstallMultipleProtocolInterfaces(). Example 93, below, expands Example 92, above, and adds a Driver Family Override Protocol instance to ImageHandle, the same handle on which the Driver Binding Protocol is installed.

Example 93-Driver Family Override Protocol Feature

#include <Uefi.h>
#include <Protocol/DriverBinding.h>
#include <Protocol/ComponentName2.h>
#include <Protocol/ComponentName.h>
#include <Protocol/DriverFamilyOverride.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Library/DebugLib.h>
#define ABC_VERSION 0x10
EFI_DRIVER_BINDING_PROTOCOL gAbcDriverBinding = {
AbcSupported,
AbcStart,
AbcStop,
ABC_VERSION,
NULL,
NULL
};
GLOBAL_REMOVE_IF_UNREFERENCED
EFI_COMPONENT_NAME_PROTOCOL gAbcComponentName = {
(EFI_COMPONENT_NAME_GET_DRIVER_NAME) AbcGetDriverName,
(EFI_COMPONENT_NAME_GET_CONTROLLER_NAME) AbcGetControllerName,
"eng"
};
GLOBAL_REMOVE_IF_UNREFERENCED
EFI_COMPONENT_NAME2_PROTOCOL gAbcComponentName2 = { AbcGetDriverName,
AbcGetControllerName,
"en"
};
GLOBAL_REMOVE_IF_UNREFERENCED
EFI_DRIVER_FAMILY_OVERRIDE_PROTOCOL gAbcDriverFamilyOverride = {
AbcGetVersion
};
EFI_STATUS
EFIAPI
AbcDriverEntryPoint (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
EFI_STATUS Status;
//
// Install driver model protocol(s) on ImageHandle
//
Status = EfiLibInstallDriverBindingComponentName2 (
ImageHandle, // ImageHandle
SystemTable, // SystemTable
&gAbcDriverBinding, // DriverBinding
ImageHandle, // DriverBindingHandle
&gAbcComponentName, // ComponentName
&gAbcComponentName2 // ComponentName2
);
ASSERT_EFI_ERROR (Status);
//
// Install Driver Family Override Protocol onto ImageHandle
//
Status = gBS->InstallMultipleProtocolInterfaces (
&ImageHandle,
&gEfiDriverFamilyOverrideProtocolGuid,
&gAbcDriverFamilyOverride,
NULL
);
ASSERT_EFI_ERROR (Status);
return Status;
}