i think it works

code/boot/include/protocol/legacyboot.h

@@ -0,0 +1,119 @@
+/*++
+
+Copyright (c) 1999 Intel Corporation
+
+Module Name:
+
+    legacyboot
+
+Abstract:
+
+    EFI support for legacy boot
+
+
+
+Revision History
+
+--*/
+
+#ifndef _LEGACY_BOOT_INCLUDE_
+#define _LEGACY_BOOT_INCLUDE_
+
+#define LEGACY_BOOT_PROTOCOL \
+    { 0x376e5eb2, 0x30e4, 0x11d3, { 0xba, 0xe5, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } }
+
+#pragma pack(1)
+
+//
+// BBS 1.01 (See Appendix A) IPL and BCV Table Entry Data structure.
+//  Seg:Off pointers have been converted to EFI pointers in this data structure
+//  This is the structure that also maps to the EFI device path for the boot selection
+//
+typedef struct {
+    UINT16  DeviceType;
+    UINT16  StatusFlag;
+    UINT32  Reserved;
+    VOID* BootHandler;   // Not an EFI entry point
+    CHAR8* DescString;
+} BBS_TABLE_ENTRY;
+#pragma pack()
+
+typedef
+EFI_STATUS
+(EFIAPI* LEGACY_BOOT_CALL) (
+    IN EFI_DEVICE_PATH* DevicePath
+    );
+
+
+//
+// BBS support functions
+//  PnP Call numbers and BiosSelector hidden in implementation
+//
+
+typedef enum {
+    IplRelative,
+    BcvRelative
+} BBS_TYPE;
+
+INTERFACE_DECL(_LEGACY_BOOT_INTERFACE);
+
+//
+// == PnP Function 0x60 then BbsVersion == 0x0101 if this call fails then BbsVersion == 0x0000
+//
+
+//
+// == PnP Function 0x61
+//
+typedef
+EFI_STATUS
+(EFIAPI* GET_DEVICE_COUNT) (
+    IN  struct _LEGACY_BOOT_INTERFACE* This,
+    IN  BBS_TYPE* TableType,
+    OUT UINTN* DeviceCount,
+    OUT UINTN* MaxCount
+    );
+
+//
+// == PnP Function 0x62
+//
+typedef
+EFI_STATUS
+(EFIAPI* GET_PRIORITY_AND_TABLE) (
+    IN  struct _LEGACY_BOOT_INTERFACE* This,
+    IN  BBS_TYPE* TableType,
+    IN OUT  UINTN* PrioritySize, // MaxCount * sizeof(UINT8)
+    OUT     UINTN* Priority,
+    IN OUT  UINTN* TableSize,    // MaxCount * sizeof(BBS_TABLE_ENTRY)
+    OUT BBS_TABLE_ENTRY* TableEntrySize
+    );
+
+//
+// == PnP Function 0x63
+//
+typedef
+EFI_STATUS
+(EFIAPI* SET_PRIORITY) (
+    IN  struct _LEGACY_BOOT_INTERFACE* This,
+    IN  BBS_TYPE* TableType,
+    IN OUT  UINTN* PrioritySize,
+    OUT     UINTN* Priority
+    );
+
+typedef struct _LEGACY_BOOT_INTERFACE {
+    LEGACY_BOOT_CALL    BootIt;
+
+    //
+    // New functions to allow BBS booting to be configured from EFI
+    //
+    UINTN                   BbsVersion;     // Currently 0x0101
+    GET_DEVICE_COUNT        GetDeviceCount;
+    GET_PRIORITY_AND_TABLE  GetPriorityAndTable;
+    SET_PRIORITY            SetPriority;   
+} LEGACY_BOOT_INTERFACE;
+
+EFI_STATUS
+PlInitializeLegacyBoot (
+    VOID
+    );
+
+#endif