Data Structures
struct	EFI_COMPATIBILITY16_TABLE

struct	EFI_DISPATCH_OPROM_TABLE

struct	EFI_TO_COMPATIBILITY16_INIT_TABLE

struct	DEVICE_PRODUCER_SERIAL

struct	DEVICE_PRODUCER_PARALLEL
	@) More...

struct	DEVICE_PRODUCER_FLOPPY

struct	LEGACY_DEVICE_FLAGS

struct	DEVICE_PRODUCER_DATA_HEADER

struct	ATAPI_IDENTIFY

struct	HDD_INFO

struct	BBS_STATUS_FLAGS

struct	BBS_TABLE

struct	SMM_ATTRIBUTES

struct	SMM_FUNCTION

struct	SMM_ENTRY

struct	SMM_TABLE

struct	UDC_ATTRIBUTES

struct	UD_TABLE

struct	EFI_TO_COMPATIBILITY16_BOOT_TABLE

struct	EFI_LEGACY_INSTALL_PCI_HANDLER

struct	EFI_EFLAGS_REG

struct	EFI_DWORD_REGS

struct	EFI_FLAGS_REG

struct	EFI_WORD_REGS

struct	EFI_BYTE_REGS

union	EFI_IA32_REGISTER_SET

struct	_EFI_LEGACY_BIOS_PROTOCOL

Macros
#define	EFI_COMPATIBILITY16_TABLE_SIGNATURE SIGNATURE_32 ('I', 'F', 'E', '$')

#define	HDD_PRIMARY 0x01

#define	HDD_SECONDARY 0x02

#define	HDD_MASTER_ATAPI_CDROM 0x04

#define	HDD_SLAVE_ATAPI_CDROM 0x08

#define	HDD_MASTER_IDE 0x20

#define	HDD_SLAVE_IDE 0x40

#define	HDD_MASTER_ATAPI_ZIPDISK 0x10

#define	HDD_SLAVE_ATAPI_ZIPDISK 0x80

#define	EFI_TO_LEGACY_MAJOR_VERSION 0x02

#define	EFI_TO_LEGACY_MINOR_VERSION 0x00

#define	MAX_IDE_CONTROLLER 8

#define	EFI_LEGACY_BIOS_PROTOCOL_GUID

#define	NO_ROM 0x00

#define	ROM_FOUND 0x01

#define	VALID_LEGACY_ROM 0x02

#define	ROM_WITH_CONFIG 0x04
	Not defined in the Framework CSM Specification. More...

#define	CARRY_FLAG 0x01

#define	ACCESS_PAGE0_CODE(statements)


#define	DEVICE_SERIAL_MODE_NORMAL 0x00

#define	DEVICE_SERIAL_MODE_IRDA 0x01

#define	DEVICE_SERIAL_MODE_ASK_IR 0x02

#define	DEVICE_SERIAL_MODE_DUPLEX_HALF 0x00

#define	DEVICE_SERIAL_MODE_DUPLEX_FULL 0x10

#define	DEVICE_PARALLEL_MODE_MODE_OUTPUT_ONLY 0x00

#define	DEVICE_PARALLEL_MODE_MODE_BIDIRECTIONAL 0x01

#define	DEVICE_PARALLEL_MODE_MODE_EPP 0x02

#define	DEVICE_PARALLEL_MODE_MODE_ECP 0x03


#define	BBS_FLOPPY 0x01

#define	BBS_HARDDISK 0x02

#define	BBS_CDROM 0x03

#define	BBS_PCMCIA 0x04

#define	BBS_USB 0x05

#define	BBS_EMBED_NETWORK 0x06

#define	BBS_BEV_DEVICE 0x80

#define	BBS_UNKNOWN 0xff


#define	BBS_DO_NOT_BOOT_FROM 0xFFFC

#define	BBS_LOWEST_PRIORITY 0xFFFD

#define	BBS_UNPRIORITIZED_ENTRY 0xFFFE

#define	BBS_IGNORE_ENTRY 0xFFFF


#define	STANDARD_IO 0x00

#define	STANDARD_MEMORY 0x01


#define	PORT_SIZE_8 0x00

#define	PORT_SIZE_16 0x01

#define	PORT_SIZE_32 0x02

#define	PORT_SIZE_64 0x03


#define	DATA_SIZE_8 0x00

#define	DATA_SIZE_16 0x01

#define	DATA_SIZE_32 0x02

#define	DATA_SIZE_64 0x03


#define	INT15_D042 0x0000

#define	GET_USB_BOOT_INFO 0x0001

#define	DMI_PNP_50_57 0x0002


#define	STANDARD_OWNER 0x0

#define	OEM_OWNER 0x1


#define	EFI_SEGMENT(_Adr) (UINT16) ((UINT16) (((UINTN) (_Adr)) >> 4) & 0xf000)

#define	EFI_OFFSET(_Adr) (UINT16) (((UINT16) ((UINTN) (_Adr))) & 0xffff)

Typedefs
typedef UINT8	SERIAL_MODE

typedef UINT8	PARALLEL_MODE

typedef struct _EFI_LEGACY_BIOS_PROTOCOL	EFI_LEGACY_BIOS_PROTOCOL

typedef BOOLEAN(EFIAPI *	EFI_LEGACY_BIOS_INT86 )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN UINT8 BiosInt, IN OUT EFI_IA32_REGISTER_SET Regs)

typedef BOOLEAN(EFIAPI *	EFI_LEGACY_BIOS_FARCALL86 )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN UINT16 Segment, IN UINT16 Offset, IN EFI_IA32_REGISTER_SET Regs, IN VOID *Stack, IN UINTN StackSize)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_CHECK_ROM )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN EFI_HANDLE PciHandle, OUT VOID RomImage, OUT UINTN RomSize, OUT UINTN *Flags)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_INSTALL_ROM )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN EFI_HANDLE PciHandle, IN VOID RomImage, OUT UINTN Flags, OUT UINT8 DiskStart, OUT UINT8 DiskEnd, OUT VOID *RomShadowAddress, OUT UINT32 ShadowedRomSize)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_BOOT )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN BBS_BBS_DEVICE_PATH BootOption, IN UINT32 LoadOptionsSize, IN VOID *LoadOptions)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_UPDATE_KEYBOARD_LED_STATUS )(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINT8 Leds)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_GET_BBS_INFO )(IN EFI_LEGACY_BIOS_PROTOCOL This, OUT UINT16 HddCount, OUT HDD_INFO *HddInfo, OUT UINT16 BbsCount, IN OUT BBS_TABLE **BbsTable)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_PREPARE_TO_BOOT_EFI )(IN EFI_LEGACY_BIOS_PROTOCOL This, OUT UINT16 BbsCount, OUT BBS_TABLE **BbsTable)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_BOOT_UNCONVENTIONAL_DEVICE )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN UDC_ATTRIBUTES Attributes, IN UINTN BbsEntry, IN VOID BeerData, IN VOID *ServiceAreaData)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_SHADOW_ALL_LEGACY_OPROMS )(IN EFI_LEGACY_BIOS_PROTOCOL *This)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_GET_LEGACY_REGION )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN UINTN LegacyMemorySize, IN UINTN Region, IN UINTN Alignment, OUT VOID *LegacyMemoryAddress)

typedef EFI_STATUS(EFIAPI *	EFI_LEGACY_BIOS_COPY_LEGACY_REGION )(IN EFI_LEGACY_BIOS_PROTOCOL This, IN UINTN LegacyMemorySize, IN VOID LegacyMemoryAddress, IN VOID *LegacyMemorySourceAddress)

Enumerations
enum	EFI_COMPATIBILITY_FUNCTIONS { Legacy16InitializeYourself = 0x0000, Legacy16UpdateBbs = 0x0001, Legacy16PrepareToBoot = 0x0002, Legacy16Boot = 0x0003, Legacy16RetrieveLastBootDevice = 0x0004, Legacy16DispatchOprom = 0x0005, Legacy16GetTableAddress = 0x0006, Legacy16SetKeyboardLeds = 0x0007, Legacy16InstallPciHandler = 0x0008 }

Variables
EFI_GUID	gEfiLegacyBiosProtocolGuid

Detailed Description

The EFI Legacy BIOS Protocol is used to abstract legacy Option ROM usage under EFI and Legacy OS boot. This file also includes all the related COMPATIBILITY16 structures and definitions.

Note: The names for EFI_IA32_REGISTER_SET elements were picked to follow well known naming conventions.

Thunk is the code that switches from 32-bit protected environment into the 16-bit real-mode environment. Reverse thunk is the code that does the opposite.

Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Revision Reference:: This protocol is defined in Framework for EFI Compatibility Support Module spec Version 0.98.

Macro Definition Documentation

#define ACCESS_PAGE0_CODE ( statements )

Value:

do {                                                          \
    EFI_STATUS                            Status_;              \
    EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc_;                \
                                                                \
    Desc_.Attributes = 0;                                       \
    Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_);        \
    ASSERT_EFI_ERROR (Status_);                                 \
    if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
      Status_ = gDS->SetMemorySpaceAttributes (                 \
                      0,                                        \
                      EFI_PAGES_TO_SIZE(1),                     \
                      Desc_.Attributes & ~(UINT64)EFI_MEMORY_RP \
                      );                                        \
      ASSERT_EFI_ERROR (Status_);                               \
    }                                                           \
                                                                \
    {                                                           \
      statements;                                               \
    }                                                           \
                                                                \
    if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
      Status_ = gDS->SetMemorySpaceAttributes (                 \
                      0,                                        \
                      EFI_PAGES_TO_SIZE(1),                     \
                      Desc_.Attributes                          \
                      );                                        \
      ASSERT_EFI_ERROR (Status_);                               \
    }                                                           \
  } while (FALSE)

#define BBS_BEV_DEVICE 0x80

BBS device type values

#define BBS_CDROM 0x03

BBS device type values

#define BBS_DO_NOT_BOOT_FROM 0xFFFC

BBS boot priority values

#define BBS_EMBED_NETWORK 0x06

BBS device type values

#define BBS_FLOPPY 0x01

BBS device type values

#define BBS_HARDDISK 0x02

BBS device type values

#define BBS_IGNORE_ENTRY 0xFFFF

BBS boot priority values

#define BBS_LOWEST_PRIORITY 0xFFFD

BBS boot priority values

#define BBS_PCMCIA 0x04

BBS device type values

#define BBS_UNKNOWN 0xff

BBS device type values

#define BBS_UNPRIORITIZED_ENTRY 0xFFFE

BBS boot priority values

#define BBS_USB 0x05

BBS device type values

#define CARRY_FLAG 0x01

#define DATA_SIZE_16 0x01

SMM_ATTRIBUTES data size constants.

#define DATA_SIZE_32 0x02

SMM_ATTRIBUTES data size constants.

#define DATA_SIZE_64 0x03

SMM_ATTRIBUTES data size constants.

#define DATA_SIZE_8 0x00

SMM_ATTRIBUTES data size constants.

#define DEVICE_PARALLEL_MODE_MODE_BIDIRECTIONAL 0x01

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_PARALLEL_MODE_MODE_ECP 0x03

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_PARALLEL_MODE_MODE_EPP 0x02

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_PARALLEL_MODE_MODE_OUTPUT_ONLY 0x00

DEVICE_PRODUCER_PARALLEL's modes.

#define DEVICE_SERIAL_MODE_ASK_IR 0x02

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_SERIAL_MODE_DUPLEX_FULL 0x10

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_SERIAL_MODE_DUPLEX_HALF 0x00

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_SERIAL_MODE_IRDA 0x01

DEVICE_PRODUCER_SERIAL's modes.

#define DEVICE_SERIAL_MODE_NORMAL 0x00

DEVICE_PRODUCER_SERIAL's modes.

#define DMI_PNP_50_57 0x0002

SMM_FUNCTION Function constants.

#define EFI_COMPATIBILITY16_TABLE_SIGNATURE SIGNATURE_32 ('I', 'F', 'E', '$')

#define EFI_LEGACY_BIOS_PROTOCOL_GUID

Value:

{ \
    0xdb9a1e3d, 0x45cb, 0x4abb, {0x85, 0x3b, 0xe5, 0x38, 0x7f, 0xdb, 0x2e, 0x2d } \
  }

#define EFI_OFFSET ( _Adr ) (UINT16) (((UINT16) ((UINTN) (_Adr))) & 0xffff)

The following macros do not appear in the Framework CSM Specification and are kept for backward compatibility only. They convert 32-bit address (_Adr) to Segment:Offset 16-bit form.

#define EFI_SEGMENT ( _Adr ) (UINT16) ((UINT16) (((UINTN) (_Adr)) >> 4) & 0xf000)

The following macros do not appear in the Framework CSM Specification and are kept for backward compatibility only. They convert 32-bit address (_Adr) to Segment:Offset 16-bit form.

#define EFI_TO_LEGACY_MAJOR_VERSION 0x02

#define EFI_TO_LEGACY_MINOR_VERSION 0x00

#define GET_USB_BOOT_INFO 0x0001

SMM_FUNCTION Function constants.

#define HDD_MASTER_ATAPI_CDROM 0x04

#define HDD_MASTER_ATAPI_ZIPDISK 0x10

#define HDD_MASTER_IDE 0x20

#define HDD_PRIMARY 0x01

HDD_INFO status bits

#define HDD_SECONDARY 0x02

#define HDD_SLAVE_ATAPI_CDROM 0x08

#define HDD_SLAVE_ATAPI_ZIPDISK 0x80

#define HDD_SLAVE_IDE 0x40

#define INT15_D042 0x0000

SMM_FUNCTION Function constants.

#define MAX_IDE_CONTROLLER 8

#define NO_ROM 0x00

Flags returned by CheckPciRom().

#define OEM_OWNER 0x1

SMM_FUNCTION Owner constants.

#define PORT_SIZE_16 0x01

SMM_ATTRIBUTES port size constants.

#define PORT_SIZE_32 0x02

SMM_ATTRIBUTES port size constants.

#define PORT_SIZE_64 0x03

SMM_ATTRIBUTES port size constants.

#define PORT_SIZE_8 0x00

SMM_ATTRIBUTES port size constants.

#define ROM_FOUND 0x01

#define ROM_WITH_CONFIG 0x04

Not defined in the Framework CSM Specification.

#define STANDARD_IO 0x00

SMM_ATTRIBUTES type values.

#define STANDARD_MEMORY 0x01

SMM_ATTRIBUTES type values.

#define STANDARD_OWNER 0x0

SMM_FUNCTION Owner constants.

#define VALID_LEGACY_ROM 0x02

Typedef Documentation

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_BOOT)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN BBS_BBS_DEVICE_PATH *BootOption, IN UINT32 LoadOptionsSize, IN VOID *LoadOptions)

This function attempts to traditionally boot the specified BootOption. If the EFI context has been compromised, this function will not return. This procedure is not used for loading an EFI-aware OS off a traditional device. The following actions occur:

Get EFI SMBIOS data structures, convert them to a traditional format, and copy to Compatibility16.
Get a pointer to ACPI data structures and copy the Compatibility16 RSD PTR to F0000 block.
Find the traditional SMI handler from a firmware volume and register the traditional SMI handler with the EFI SMI handler.
Build onboard IDE information and pass this information to the Compatibility16 code.
Make sure all PCI Interrupt Line registers are programmed to match 8259.
Reconfigure SIO devices from EFI mode (polled) into traditional mode (interrupt driven).
Shadow all PCI ROMs.
Set up BDA and EBDA standard areas before the legacy boot.
Construct the Compatibility16 boot memory map and pass it to the Compatibility16 code.
Invoke the Compatibility16 table function Compatibility16PrepareToBoot(). This invocation causes a thunk into the Compatibility16 code, which sets all appropriate internal data structures. The boot device list is a parameter.
Invoke the Compatibility16 Table function Compatibility16Boot(). This invocation causes a thunk into the Compatibility16 code, which does an INT19.
If the Compatibility16Boot() function returns, then the boot failed in a graceful manner–meaning that the EFI code is still valid. An ungraceful boot failure causes a reset because the state of EFI code is unknown.

Parameters

[in]	This	The protocol instance pointer.
[in]	BootOption	The EFI Device Path from BootXXXX variable.
[in]	LoadOptionSize	The size of LoadOption in size.
[in]	LoadOption	LThe oadOption from BootXXXX variable.

Return values

EFI_DEVICE_ERROR Failed to boot from any boot device and memory is uncorrupted. Note: This function normally does not returns. It will either boot the OS or reset the system if memory has been "corrupted" by loading a boot sector and passing control to it.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_BOOT_UNCONVENTIONAL_DEVICE)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UDC_ATTRIBUTES Attributes, IN UINTN BbsEntry, IN VOID *BeerData, IN VOID *ServiceAreaData)

To boot from an unconventional device like parties and/or execute HDD diagnostics.

Parameters

[in]	This	The protocol instance pointer.
[in]	Attributes	How to interpret the other input parameters.
[in]	BbsEntry	The 0-based index into the BbsTable for the parent device.
[in]	BeerData	A pointer to the 128 bytes of ram BEER data.
[in]	ServiceAreaData	A pointer to the 64 bytes of raw Service Area data. The caller must provide a pointer to the specific Service Area and not the start all Service Areas.

Return values

EFI_INVALID_PARAMETER If error. Does NOT return if no error.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_CHECK_ROM)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN EFI_HANDLE PciHandle, OUT VOID **RomImage, OUT UINTN *RomSize, OUT UINTN *Flags)

Test to see if a legacy PCI ROM exists for this device. Optionally return the Legacy ROM instance for this PCI device.

Parameters

[in]	This	The protocol instance pointer.
[in]	PciHandle	The PCI PC-AT OPROM from this devices ROM BAR will be loaded
[out]	RomImage	Return the legacy PCI ROM for this device.
[out]	RomSize	The size of ROM Image.
[out]	Flags	Indicates if ROM found and if PC-AT. Multiple bits can be set as follows: 00 = No ROM. 01 = ROM Found. 02 = ROM is a valid legacy ROM.

Return values

EFI_SUCCESS	The Legacy Option ROM available for this device
EFI_UNSUPPORTED	The Legacy Option ROM is not supported.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_COPY_LEGACY_REGION)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINTN LegacyMemorySize, IN VOID *LegacyMemoryAddress, IN VOID *LegacyMemorySourceAddress)

Get a region from the LegacyBios for Tiano usage. Can only be invoked once.

Parameters

[in]	This	The protocol instance pointer.
[in]	LegacyMemorySize	The size of data to copy.
[in]	LegacyMemoryAddress	The Legacy Region destination address. Note: must be in region assigned by LegacyBiosGetLegacyRegion.
[in]	LegacyMemorySourceAddress	The source of the data to copy.

Return values

EFI_SUCCESS	The Region assigned.
EFI_ACCESS_DENIED	Destination was outside an assigned region.

typedef BOOLEAN(EFIAPI * EFI_LEGACY_BIOS_FARCALL86)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINT16 Segment, IN UINT16 Offset, IN EFI_IA32_REGISTER_SET *Regs, IN VOID *Stack, IN UINTN StackSize)

Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the 16-bit register context on entry and exit. Arguments can be passed on the Stack argument

Parameters

[in]	This	The protocol instance pointer.
[in]	Segment	The segemnt of 16-bit mode call.
[in]	Offset	The offset of 16-bit mdoe call.
[in]	Reg	Register contexted passed into (and returned) from thunk to 16-bit mode.
[in]	Stack	The caller allocated stack used to pass arguments.
[in]	StackSize	The size of Stack in bytes.

Return values

FALSE	Thunk completed with no BIOS errors in the target code. See Regs for status.
TRUE	There was a BIOS error in the target code.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_GET_BBS_INFO)(IN EFI_LEGACY_BIOS_PROTOCOL *This, OUT UINT16 *HddCount, OUT HDD_INFO **HddInfo, OUT UINT16 *BbsCount, IN OUT BBS_TABLE **BbsTable)

Retrieve legacy BBS info and assign boot priority.

Parameters

[in]	This	The protocol instance pointer.
[out]	HddCount	The number of HDD_INFO structures.
[out]	HddInfo	Onboard IDE controller information.
[out]	BbsCount	The number of BBS_TABLE structures.
[in,out]	BbsTable	Points to List of BBS_TABLE.

Return values

EFI_SUCCESS Tables were returned.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_GET_LEGACY_REGION)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINTN LegacyMemorySize, IN UINTN Region, IN UINTN Alignment, OUT VOID **LegacyMemoryAddress)

Get a region from the LegacyBios for S3 usage.

Parameters

[in]	This	The protocol instance pointer.
[in]	LegacyMemorySize	The size of required region.
[in]	Region	The region to use. 00 = Either 0xE0000 or 0xF0000 block. Bit0 = 1 0xF0000 block. Bit1 = 1 0xE0000 block.
[in]	Alignment	Address alignment. Bit mapped. The first non-zero bit from right is alignment.
[out]	LegacyMemoryAddress	The Region Assigned

Return values

EFI_SUCCESS	The Region was assigned.
EFI_ACCESS_DENIED	The function was previously invoked.
Other	The Region was not assigned.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_INSTALL_ROM)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN EFI_HANDLE PciHandle, IN VOID **RomImage, OUT UINTN *Flags, OUT UINT8 *DiskStart, OUT UINT8 *DiskEnd, OUT VOID **RomShadowAddress, OUT UINT32 *ShadowedRomSize)

Load a legacy PC-AT OPROM on the PciHandle device. Return information about how many disks were added by the OPROM and the shadow address and size. DiskStart & DiskEnd are INT 13h drive letters. Thus 0x80 is C:

Parameters

[in]	This	The protocol instance pointer.
[in]	PciHandle	The PCI PC-AT OPROM from this devices ROM BAR will be loaded. This value is NULL if RomImage is non-NULL. This is the normal case.
[in]	RomImage	A PCI PC-AT ROM image. This argument is non-NULL if there is no hardware associated with the ROM and thus no PciHandle, otherwise is must be NULL. Example is PXE base code.
[out]	Flags	The type of ROM discovered. Multiple bits can be set, as follows: 00 = No ROM. 01 = ROM found. 02 = ROM is a valid legacy ROM.
[out]	DiskStart	The disk number of first device hooked by the ROM. If DiskStart is the same as DiskEnd no disked were hooked.
[out]	DiskEnd	disk number of the last device hooked by the ROM.
[out]	RomShadowAddress	Shadow address of PC-AT ROM.
[out]	RomShadowSize	Size of RomShadowAddress in bytes.

Return values

EFI_SUCCESS	Thunk completed, see Regs for status.
EFI_INVALID_PARAMETER	PciHandle not found

typedef BOOLEAN(EFIAPI * EFI_LEGACY_BIOS_INT86)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINT8 BiosInt, IN OUT EFI_IA32_REGISTER_SET *Regs)

Thunk to 16-bit real mode and execute a software interrupt with a vector of BiosInt. Regs will contain the 16-bit register context on entry and exit.

Parameters

[in]	This	The protocol instance pointer.
[in]	BiosInt	The processor interrupt vector to invoke.
[in,out]	Reg	Register contexted passed into (and returned) from thunk to 16-bit mode.

Return values

TRUE	Thunk completed with no BIOS errors in the target code. See Regs for status.
FALSE	There was a BIOS error in the target code.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_PREPARE_TO_BOOT_EFI)(IN EFI_LEGACY_BIOS_PROTOCOL *This, OUT UINT16 *BbsCount, OUT BBS_TABLE **BbsTable)

Assign drive number to legacy HDD drives prior to booting an EFI aware OS so the OS can access drives without an EFI driver.

Parameters

[in]	This	The protocol instance pointer.
[out]	BbsCount	The number of BBS_TABLE structures
[out]	BbsTable	List of BBS entries

Return values

EFI_SUCCESS Drive numbers assigned.

typedef struct _EFI_LEGACY_BIOS_PROTOCOL EFI_LEGACY_BIOS_PROTOCOL

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_SHADOW_ALL_LEGACY_OPROMS)(IN EFI_LEGACY_BIOS_PROTOCOL *This)

Shadow all legacy16 OPROMs that haven't been shadowed. Warning: Use this with caution. This routine disconnects all EFI drivers. If used externally, then the caller must re-connect EFI drivers.

Parameters

[in] This The protocol instance pointer.

Return values

EFI_SUCCESS OPROMs were shadowed.

typedef EFI_STATUS(EFIAPI * EFI_LEGACY_BIOS_UPDATE_KEYBOARD_LED_STATUS)(IN EFI_LEGACY_BIOS_PROTOCOL *This, IN UINT8 Leds)

This function takes the Leds input parameter and sets/resets the BDA accordingly. Leds is also passed to Compatibility16 code, in case any special processing is required. This function is normally called from EFI Setup drivers that handle user-selectable keyboard options such as boot with NUM LOCK on/off. This function does not touch the keyboard or keyboard LEDs but only the BDA.

Parameters

[in]	This	The protocol instance pointer.
[in]	Leds	The status of current Scroll, Num & Cap lock LEDS: Bit 0 is Scroll Lock 0 = Not locked. Bit 1 is Num Lock. Bit 2 is Caps Lock.

Return values

EFI_SUCCESS The BDA was updated successfully.

typedef UINT8 PARALLEL_MODE

typedef UINT8 SERIAL_MODE

Enumeration Type Documentation

enum EFI_COMPATIBILITY_FUNCTIONS

Functions provided by the CSM binary which communicate between the EfiCompatibility and Compatibility16 code.

Inconsistent with the specification here: The member's name started with "Compatibility16" [defined in Intel Framework Compatibility Support Module Specification / 0.97 version] has been changed to "Legacy16" since keeping backward compatible.

Enumerator
Legacy16InitializeYourself	Causes the Compatibility16 code to do any internal initialization required. Input: AX = Compatibility16InitializeYourself ES:BX = Pointer to EFI_TO_COMPATIBILITY16_INIT_TABLE Return: AX = Return Status codes
Legacy16UpdateBbs	Causes the Compatibility16 BIOS to perform any drive number translations to match the boot sequence. Input: AX = Compatibility16UpdateBbs ES:BX = Pointer to EFI_TO_COMPATIBILITY16_BOOT_TABLE Return: AX = Returned status codes
Legacy16PrepareToBoot	Allows the Compatibility16 code to perform any final actions before booting. The Compatibility16 code is read/write. Input: AX = Compatibility16PrepareToBoot ES:BX = Pointer to EFI_TO_COMPATIBILITY16_BOOT_TABLE structure Return: AX = Returned status codes
Legacy16Boot	Causes the Compatibility16 BIOS to boot. The Compatibility16 code is Read/Only. Input: AX = Compatibility16Boot Output: AX = Returned status codes
Legacy16RetrieveLastBootDevice	Allows the Compatibility16 code to get the last device from which a boot was attempted. This is stored in CMOS and is the priority number of the last attempted boot device. Input: AX = Compatibility16RetrieveLastBootDevice Output: AX = Returned status codes BX = Priority number of the boot device.
Legacy16DispatchOprom	Allows the Compatibility16 code rehook INT13, INT18, and/or INT19 after dispatching a legacy OpROM. Input: AX = Compatibility16DispatchOprom ES:BX = Pointer to EFI_DISPATCH_OPROM_TABLE Output: AX = Returned status codes BX = Number of non-BBS-compliant devices found. Equals 0 if BBS compliant.
Legacy16GetTableAddress	Finds a free area in the 0xFxxxx or 0xExxxx region of the specified length and returns the address of that region. Input: AX = Compatibility16GetTableAddress BX = Allocation region 00 = Allocate from either 0xE0000 or 0xF0000 64 KB blocks. Bit 0 = 1 Allocate from 0xF0000 64 KB block Bit 1 = 1 Allocate from 0xE0000 64 KB block CX = Requested length in bytes. DX = Required address alignment. Bit mapped. First non-zero bit from the right is the alignment. Output: AX = Returned status codes DS:BX = Address of the region
Legacy16SetKeyboardLeds	Enables the EfiCompatibility module to do any nonstandard processing of keyboard LEDs or state. Input: AX = Compatibility16SetKeyboardLeds CL = LED status. Bit 0 Scroll Lock 0 = Off Bit 1 NumLock Bit 2 Caps Lock Output: AX = Returned status codes
Legacy16InstallPciHandler	Enables the EfiCompatibility module to install an interrupt handler for PCI mass media devices that do not have an OpROM associated with them. An example is SATA. Input: AX = Compatibility16InstallPciHandler ES:BX = Pointer to EFI_LEGACY_INSTALL_PCI_HANDLER structure Output: AX = Returned status codes

Variable Documentation

EFI_GUID gEfiLegacyBiosProtocolGuid

Data Structures

Macros

Typedefs

Enumerations

Variables

Detailed Description

Macro Definition Documentation

Typedef Documentation

Enumeration Type Documentation

Variable Documentation