MmAccess.h File Reference

Data Structures
struct	_EFI_MM_ACCESS_PROTOCOL

Macros
#define	EFI_MM_ACCESS_PROTOCOL_GUID

Typedefs
typedef struct _EFI_MM_ACCESS_PROTOCOL	EFI_MM_ACCESS_PROTOCOL
typedef EFI_STATUS(EFIAPI *	EFI_MM_OPEN )(IN EFI_MM_ACCESS_PROTOCOL *This)
typedef EFI_STATUS(EFIAPI *	EFI_MM_CLOSE )(IN EFI_MM_ACCESS_PROTOCOL *This)
typedef EFI_STATUS(EFIAPI *	EFI_MM_LOCK )(IN EFI_MM_ACCESS_PROTOCOL *This)
typedef EFI_STATUS(EFIAPI *	EFI_MM_CAPABILITIES )(IN CONST EFI_MM_ACCESS_PROTOCOL *This, IN OUT UINTN *MmramMapSize, IN OUT EFI_MMRAM_DESCRIPTOR *MmramMap)

Variables
EFI_GUID	gEfiMmAccessProtocolGuid

Detailed Description

EFI MM Access Protocol as defined in the PI 1.5 specification.

This protocol is used to control the visibility of the MMRAM on the platform. It abstracts the location and characteristics of MMRAM. The expectation is that the north bridge or memory controller would publish this protocol.

The principal functionality found in the memory controller includes the following:

• Exposing the MMRAM to all non-MM agents, or the "open" state
• Shrouding the MMRAM to all but the MM agents, or the "closed" state
• Preserving the system integrity, or "locking" the MMRAM, such that the settings cannot be perturbed by either boot service or runtime agents

Copyright (c) 2017, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Macro Definition Documentation

#define EFI_MM_ACCESS_PROTOCOL_GUID

Value:

{ \
     0xc2702b74, 0x800c, 0x4131, {0x87, 0x46, 0x8f, 0xb5, 0xb8, 0x9c, 0xe4, 0xac } \
  }

Typedef Documentation

typedef struct _EFI_MM_ACCESS_PROTOCOL EFI_MM_ACCESS_PROTOCOL

typedef EFI_STATUS(EFIAPI * EFI_MM_CAPABILITIES)(IN CONST EFI_MM_ACCESS_PROTOCOL *This, IN OUT UINTN *MmramMapSize, IN OUT EFI_MMRAM_DESCRIPTOR *MmramMap)

Queries the memory controller for the possible regions that will support MMRAM.

Parameters

[in]	This	The EFI_MM_ACCESS_PROTOCOL instance.
[in,out]	MmramMapSize	A pointer to the size, in bytes, of the MmramMemoryMap buffer.
[in,out]	MmramMap	A pointer to the buffer in which firmware places the current memory map.

Return values

EFI_SUCCESS	The chipset supported the given resource.
EFI_BUFFER_TOO_SMALL	The MmramMap parameter was too small. The current buffer size needed to hold the memory map is returned in MmramMapSize.

typedef EFI_STATUS(EFIAPI * EFI_MM_CLOSE)(IN EFI_MM_ACCESS_PROTOCOL *This)

Inhibits access to the MMRAM.

This function "closes" MMRAM so that it is not visible while outside of MM. The function should return EFI_UNSUPPORTED if the hardware does not support hiding of MMRAM.

Parameters

[in]

This

The EFI_MM_ACCESS_PROTOCOL instance.

Return values

EFI_SUCCESS	The operation was successful.
EFI_UNSUPPORTED	The system does not support opening and closing of MMRAM.
EFI_DEVICE_ERROR	MMRAM cannot be closed.

typedef EFI_STATUS(EFIAPI * EFI_MM_LOCK)(IN EFI_MM_ACCESS_PROTOCOL *This)

Inhibits access to the MMRAM.

This function prohibits access to the MMRAM region. This function is usually implemented such that it is a write-once operation.

Parameters

[in]

This

The EFI_MM_ACCESS_PROTOCOL instance.

Return values

EFI_SUCCESS	The device was successfully locked.
EFI_UNSUPPORTED	The system does not support locking of MMRAM.

typedef EFI_STATUS(EFIAPI * EFI_MM_OPEN)(IN EFI_MM_ACCESS_PROTOCOL *This)

Opens the MMRAM area to be accessible by a boot-service driver.

This function "opens" MMRAM so that it is visible while not inside of MM. The function should return EFI_UNSUPPORTED if the hardware does not support hiding of MMRAM. The function should return EFI_DEVICE_ERROR if the MMRAM configuration is locked.

Parameters

[in]

This

The EFI_MM_ACCESS_PROTOCOL instance.

Return values

EFI_SUCCESS	The operation was successful.
EFI_UNSUPPORTED	The system does not support opening and closing of MMRAM.
EFI_DEVICE_ERROR	MMRAM cannot be opened, perhaps because it is locked.

Variable Documentation

EFI_GUID gEfiMmAccessProtocolGuid