mirror of
https://github.com/tianocore/edk2
synced 2026-08-27 00:23:19 -04:00
7a934d0bef
Replace traditional `#ifndef`/`#define`/`#endif` include guards with
`#pragma` once.
`#pragma once` is a widely supported preprocessor directive that
prevents header files from being included multiple times. It is
supported by all toolchains used to build edk2: GCC, Clang/LLVM, and
MSVC.
Compared to macro-based include guards, `#pragma once`:
- Eliminates the risk of macro name collisions or copy/paste errors
where two headers inadvertently use the same guard macro.
- Eliminate inconsistency in the way include guard macros are named
(e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.).
- Reduces boilerplate (three lines replaced by one).
- Avoids polluting the macro namespace with guard symbols.
- Can improve build times as the preprocessor can skip re-opening the
file entirely, rather than re-reading it to find the matching
`#endif` ("multiple-include optimization").
- Note that some compilers may already optimize traditional include
guards, by recognzining the idiomatic pattern.
This change is made acknowledging that overall portability of the
code will technically be reduced, as `#pragma once` is not part of the
C/C++ standards.
However, this is considered acceptable given:
1. edk2 already defines a subset of supported compilers in
BaseTools/Conf/tools_def.template, all of which have supported
`#pragma once` for over two decades.
2. There have been concerns raised to the project about inconsistent
include guard naming and potential macro collisions.
Approximate compiler support dates:
- MSVC: Supported since Visual C++ 4.2 (1996)
- GCC: Supported since 3.4 (2004)
(http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html)
- Clang (LLVM based): Since initial release in 2007
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
/** @file
|
|
MM Communication buffer data.
|
|
|
|
Copyright (c) 2024, Intel Corporation. All rights reserved.<BR>
|
|
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
///
|
|
/// The GUID of the MM Communication buffer HOB.
|
|
///
|
|
#define MM_COMM_BUFFER_HOB_GUID \
|
|
{ 0x6c2a2520, 0x0131, 0x4aee, { 0xa7, 0x50, 0xcc, 0x38, 0x4a, 0xac, 0xe8, 0xc6 }}
|
|
|
|
///
|
|
/// The MM communicate buffer facilitates data sharing between non-MM and MM code.
|
|
/// The MM IPL code allocates a "fixed" runtime type memory as the MM communication buffer,
|
|
/// and communicates its address and size to MM Core via MmCommBuffer GUIDed HOB.
|
|
/// Here, "fixed" implies that the buffer's location remains constant throughout the boot process.
|
|
/// Data is exchanged between the MM Communication PPI/Protocol and a software MMI handler
|
|
/// using this fixed MM communication buffer.
|
|
///
|
|
typedef struct {
|
|
///
|
|
/// The address of the 4-KiB aligned fixed MM communication buffer.
|
|
///
|
|
EFI_PHYSICAL_ADDRESS PhysicalStart;
|
|
|
|
///
|
|
/// Size of the fixed MM communication buffer, in 4KiB pages.
|
|
///
|
|
UINT64 NumberOfPages;
|
|
|
|
///
|
|
/// Point to MM_COMM_BUFFER_STATUS structure.
|
|
///
|
|
EFI_PHYSICAL_ADDRESS Status;
|
|
} MM_COMM_BUFFER;
|
|
|
|
typedef struct {
|
|
///
|
|
/// Whether the data in the fixed MM communication buffer is valid when entering from non-MM to MM.
|
|
///
|
|
BOOLEAN IsCommBufferValid;
|
|
|
|
/// For padding purpose
|
|
UINT8 Reserved[7];
|
|
|
|
///
|
|
/// The return status when returning from MM to non-MM.
|
|
///
|
|
UINT64 ReturnStatus;
|
|
|
|
///
|
|
/// The size in bytes of the output buffer when returning from MM to non-MM.
|
|
///
|
|
UINT64 ReturnBufferSize;
|
|
} MM_COMM_BUFFER_STATUS;
|
|
|
|
extern EFI_GUID gMmCommBufferHobGuid;
|