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Simple File System

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以下接口由 BootService 提供!!!

OpenProtocol

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typedef
EFI_STATUS
(EFIAPI *EFI_OPEN_PROTOCOL)(
  IN  EFI_HANDLE                Handle,
  IN  EFI_GUID                  *Protocol,
  OUT VOID                      **Interface, OPTIONAL
  IN  EFI_HANDLE                AgentHandle,
  IN  EFI_HANDLE                ControllerHandle,
  IN  UINT32                    Attributes
  );
  • Handle -> 已安装此 Protocol 的句柄
  • Protocol -> 要打开的 Protocol 的 GUID
  • Interface -> 返回的 Protocol 实例,无则NULL,可选项

  • AgentHandle -> 程序Handle

  • Attributes -> 打开 Protocol 的 参数 / 模式

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#define EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL  0x00000001 // 类似HandleProtocol()
#define EFI_OPEN_PROTOCOL_GET_PROTOCOL        0x00000002 // 从句柄上获取
#define EFI_OPEN_PROTOCOL_TEST_PROTOCOL       0x00000004 // 测试是否存在
#define EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER 0x00000008
#define EFI_OPEN_PROTOCOL_BY_DRIVER           0x00000010
#define EFI_OPEN_PROTOCOL_EXCLUSIVE           0x00000020 // 获取Protocol独占权

LocateHandle

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typedef
EFI_STATUS
(EFIAPI *EFI_LOCATE_HANDLE)(
  IN     EFI_LOCATE_SEARCH_TYPE   SearchType,
  IN     EFI_GUID                 *Protocol,    OPTIONAL
  IN     VOID                     *SearchKey,   OPTIONAL
  IN OUT UINTN                    *BufferSize,
  OUT    EFI_HANDLE               *Buffer
  );

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typedef enum {
  /// 所有 Handle
  AllHandles,
  ///
  /// Retrieve the next handle fron a RegisterProtocolNotify() event.
  ///
  ByRegisterNotify,
  /// 找出所有 Protocol (GUID)对应的Handle,忽略 SearchKey
  ByProtocol
} EFI_LOCATE_SEARCH_TYPE;

在操作成功后,Buffer 中Handle的个数为BufferSize / sizeof(EFI_HANDLE).

请在Protocol打开后完成FreePool操作!!!

LocateHandleBuffer

它与LocateHandle的最大区别在于,LocateHandle需要一个预先准备好的Buffer,而它会自己创建.

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typedef
EFI_STATUS
(EFIAPI *EFI_LOCATE_HANDLE_BUFFER)(
  IN     EFI_LOCATE_SEARCH_TYPE       SearchType,
  IN     EFI_GUID                     *Protocol,      OPTIONAL
  IN     VOID                         *SearchKey,     OPTIONAL
  IN OUT UINTN                        *NoHandles,
  OUT    EFI_HANDLE                   **Buffer
  );

GUID 的定义

一般在头文件中写的清清楚楚,但是是宏的形式,并未有实际定义全局变量.我们可以采取以下解决方案:

  1. 不使用全局变量,自己定义
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EFI_GUID EfiSimpleFileSystemProtocolGuid = (EFI_GUID)EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
  1. 使用全局变量,在inf文件中声明,在编译生成AutoGen.c时定义
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[Protocols]
    gEfiSimpleFileSystemProtocolGuid

参考

  • src/boot/SigmaBootPkg/File.c