UEFI开发与调试--edk2中的基础组件
还记得前面介绍的MdePkg和MdeModulePkg吗？这两个包中会实现UEFI内核中的基础组件，其中就包括了系统表，启动服务表，运行时服务表。
系统表（System Table）
系统表是edk2提供的一个最重要也是最基础的数据结构之一，它是沟通内核和应用/驱动的桥梁。通过系统表，应用程序和驱动才能够访问到内核和硬件资源。系统表包含了如下信息：
- 表头
- 固件信息
- 标准输入设备，标准输出设备，标准错误输出设备
- 启动服务表
- 运行时服务表
- 系统配置表
它的结构体定义在MdePkg/Include/Uefi/UefiSpec.h:
///
/// EFI System Table
///
typedef struct {
///
/// The table header for the EFI System Table.
///
EFI_TABLE_HEADER Hdr;
///
/// A pointer to a null terminated string that identifies the vendor
/// that produces the system firmware for the platform.
///
CHAR16 *FirmwareVendor;
///
/// A firmware vendor specific value that identifies the revision
/// of the system firmware for the platform.
///
UINT32 FirmwareRevision;
///
/// The handle for the active console input device. This handle must support
/// EFI_SIMPLE_TEXT_INPUT_PROTOCOL and EFI_SIMPLE_TEXT_INPUT_EX_PROTOCOL.
///
EFI_HANDLE ConsoleInHandle;
///
/// A pointer to the EFI_SIMPLE_TEXT_INPUT_PROTOCOL interface that is
/// associated with ConsoleInHandle.
///
EFI_SIMPLE_TEXT_INPUT_PROTOCOL *ConIn;
///
/// The handle for the active console output device.
///
EFI_HANDLE ConsoleOutHandle;
///
/// A pointer to the EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL interface
/// that is associated with ConsoleOutHandle.
///
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *ConOut;
///
/// The handle for the active standard error console device.
/// This handle must support the EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL.
///
EFI_HANDLE StandardErrorHandle;
///
/// A pointer to the EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL interface
/// that is associated with StandardErrorHandle.
///
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *StdErr;
///
/// A pointer to the EFI Runtime Services Table.
///
EFI_RUNTIME_SERVICES *RuntimeServices;
///
/// A pointer to the EFI Boot Services Table.
///
EFI_BOOT_SERVICES *BootServices;
///
/// The number of system configuration tables in the buffer ConfigurationTable.
///
UINTN NumberOfTableEntries;
///
/// A pointer to the system configuration tables.
/// The number of entries in the table is NumberOfTableEntries.
///
EFI_CONFIGURATION_TABLE *ConfigurationTable;
} EFI_SYSTEM_TABLE;
在UEFI中会定义一个初始化的System Table，在MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c:
EFI_SYSTEM_TABLE mEfiSystemTableTemplate = {
{
EFI_SYSTEM_TABLE_SIGNATURE, // Signature
EFI_SYSTEM_TABLE_REVISION, // Revision
sizeof (EFI_SYSTEM_TABLE), // HeaderSize
0, // CRC32
0 // Reserved
},
NULL, // FirmwareVendor
0, // FirmwareRevision
NULL, // ConsoleInHandle
NULL, // ConIn
NULL, // ConsoleOutHandle
NULL, // ConOut
NULL, // StandardErrorHandle
NULL, // StdErr
NULL, // RuntimeServices
&mBootServices, // BootServices
0, // NumberOfConfigurationTableEntries
NULL // ConfigurationTable
};
在UEFI运行到DXE阶段时，UEFI内核会以此构建System Table，具体实现也在MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c:
//
// Allocate the EFI System Table and EFI Runtime Service Table from EfiRuntimeServicesData
// Use the templates to initialize the contents of the EFI System Table and EFI Runtime Services Table
//
gDxeCoreST = AllocateRuntimeCopyPool (sizeof (EFI_SYSTEM_TABLE), &mEfiSystemTableTemplate);
ASSERT (gDxeCoreST != NULL);
经过上面的拷贝动作我们可以知道，UEFI内核构建了一个System Table，以此作为提供给应用和驱动的接口，由构建的代码可知，它只能在DXE阶段开始后才能使用。需要注意的一点是，BootServices是在mEfiSystemTableTemplate静态设置的&mBootServices，而RuntimeServices初始化设置的是NULL，所以需要后面在代码中进行构建。这部分我们将在后面介绍。
启动服务表（BootServices）
和System Table一样，结构体也是定义在MdePkg/Include/Uefi/UefiSpec.h:
/// EFI Boot Services Table.
///
typedef struct {
///
/// The table header for the EFI Boot Services Table.
///
EFI_TABLE_HEADER Hdr;
//
// Task Priority Services
//
EFI_RAISE_TPL RaiseTPL;
EFI_RESTORE_TPL RestoreTPL;
//
// Memory Services
//
EFI_ALLOCATE_PAGES AllocatePages;
EFI_FREE_PAGES FreePages;
EFI_GET_MEMORY_MAP GetMemoryMap;
EFI_ALLOCATE_POOL AllocatePool;
EFI_FREE_POOL FreePool;
//
// Event & Timer Services
//
EFI_CREATE_EVENT CreateEvent;
EFI_SET_TIMER SetTimer;
EFI_WAIT_FOR_EVENT WaitForEvent;
EFI_SIGNAL_EVENT SignalEvent;
EFI_CLOSE_EVENT CloseEvent;
EFI_CHECK_EVENT CheckEvent;
//
// Protocol Handler Services
//
EFI_INSTALL_PROTOCOL_INTERFACE InstallProtocolInterface;
EFI_REINSTALL_PROTOCOL_INTERFACE ReinstallProtocolInterface;
EFI_UNINSTALL_PROTOCOL_INTERFACE UninstallProtocolInterface;
EFI_HANDLE_PROTOCOL HandleProtocol;
VOID *Reserved;
EFI_REGISTER_PROTOCOL_NOTIFY RegisterProtocolNotify;
EFI_LOCATE_HANDLE LocateHandle;
EFI_LOCATE_DEVICE_PATH LocateDevicePath;
EFI_INSTALL_CONFIGURATION_TABLE InstallConfigurationTable;
//
// Image Services
//
EFI_IMAGE_LOAD LoadImage;
EFI_IMAGE_START StartImage;
EFI_EXIT Exit;
EFI_IMAGE_UNLOAD UnloadImage;
EFI_EXIT_BOOT_SERVICES ExitBootServices;
//
// Miscellaneous Services
//
EFI_GET_NEXT_MONOTONIC_COUNT GetNextMonotonicCount;
EFI_STALL Stall;
EFI_SET_WATCHDOG_TIMER SetWatchdogTimer;
//
// DriverSupport Services
//
EFI_CONNECT_CONTROLLER ConnectController;
EFI_DISCONNECT_CONTROLLER DisconnectController;
//
// Open and Close Protocol Services
//
EFI_OPEN_PROTOCOL OpenProtocol;
EFI_CLOSE_PROTOCOL CloseProtocol;
EFI_OPEN_PROTOCOL_INFORMATION OpenProtocolInformation;
//
// Library Services
//
EFI_PROTOCOLS_PER_HANDLE ProtocolsPerHandle;
EFI_LOCATE_HANDLE_BUFFER LocateHandleBuffer;
EFI_LOCATE_PROTOCOL LocateProtocol;
EFI_INSTALL_MULTIPLE_PROTOCOL_INTERFACES InstallMultipleProtocolInterfaces;
EFI_UNINSTALL_MULTIPLE_PROTOCOL_INTERFACES UninstallMultipleProtocolInterfaces;
//
// 32-bit CRC Services
//
EFI_CALCULATE_CRC32 CalculateCrc32;
//
// Miscellaneous Services
//
EFI_COPY_MEM CopyMem;
EFI_SET_MEM SetMem;
EFI_CREATE_EVENT_EX CreateEventEx;
} EFI_BOOT_SERVICES;
从上面的注释可以看出它包含了如下的一些内容：
- 表头
- 任务优先级服务
- 内存服务
- Event&Timer服务
- Protocol相关服务
- Image服务
- 驱动支持服务
- Protocol打开和关闭服务
- 库相关服务
- 其他服务
默认的初始化变量定义在MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c:
//
// DXE Core Module Variables
//
EFI_BOOT_SERVICES mBootServices = {
{
EFI_BOOT_SERVICES_SIGNATURE, // Signature
EFI_BOOT_SERVICES_REVISION, // Revision
sizeof (EFI_BOOT_SERVICES), // HeaderSize
0, // CRC32
0 // Reserved
},
(EFI_RAISE_TPL) CoreRaiseTpl, // RaiseTPL
(EFI_RESTORE_TPL) CoreRestoreTpl, // RestoreTPL
(EFI_ALLOCATE_PAGES) CoreAllocatePages, // AllocatePages
(EFI_FREE_PAGES) CoreFreePages, // FreePages
(EFI_GET_MEMORY_MAP) CoreGetMemoryMap, // GetMemoryMap
(EFI_ALLOCATE_POOL) CoreAllocatePool, // AllocatePool
(EFI_FREE_POOL) CoreFreePool, // FreePool
(EFI_CREATE_EVENT) CoreCreateEvent, // CreateEvent
(EFI_SET_TIMER) CoreSetTimer, // SetTimer
(EFI_WAIT_FOR_EVENT) CoreWaitForEvent, // WaitForEvent
(EFI_SIGNAL_EVENT) CoreSignalEvent, // SignalEvent
(EFI_CLOSE_EVENT) CoreCloseEvent, // CloseEvent
(EFI_CHECK_EVENT) CoreCheckEvent, // CheckEvent
(EFI_INSTALL_PROTOCOL_INTERFACE) CoreInstallProtocolInterface, // InstallProtocolInterface
(EFI_REINSTALL_PROTOCOL_INTERFACE) CoreReinstallProtocolInterface, // ReinstallProtocolInterface
(EFI_UNINSTALL_PROTOCOL_INTERFACE) CoreUninstallProtocolInterface, // UninstallProtocolInterface
(EFI_HANDLE_PROTOCOL) CoreHandleProtocol, // HandleProtocol
(VOID *) NULL, // Reserved
(EFI_REGISTER_PROTOCOL_NOTIFY) CoreRegisterProtocolNotify, // RegisterProtocolNotify
(EFI_LOCATE_HANDLE) CoreLocateHandle, // LocateHandle
(EFI_LOCATE_DEVICE_PATH) CoreLocateDevicePath, // LocateDevicePath
(EFI_INSTALL_CONFIGURATION_TABLE) CoreInstallConfigurationTable, // InstallConfigurationTable
(EFI_IMAGE_LOAD) CoreLoadImage, // LoadImage
(EFI_IMAGE_START) CoreStartImage, // StartImage
(EFI_EXIT) CoreExit, // Exit
(EFI_IMAGE_UNLOAD) CoreUnloadImage, // UnloadImage
(EFI_EXIT_BOOT_SERVICES) CoreExitBootServices, // ExitBootServices
(EFI_GET_NEXT_MONOTONIC_COUNT) CoreEfiNotAvailableYetArg1, // GetNextMonotonicCount
(EFI_STALL) CoreStall, // Stall
(EFI_SET_WATCHDOG_TIMER) CoreSetWatchdogTimer, // SetWatchdogTimer
(EFI_CONNECT_CONTROLLER) CoreConnectController, // ConnectController
(EFI_DISCONNECT_CONTROLLER) CoreDisconnectController, // DisconnectController
(EFI_OPEN_PROTOCOL) CoreOpenProtocol, // OpenProtocol
(EFI_CLOSE_PROTOCOL) CoreCloseProtocol, // CloseProtocol
(EFI_OPEN_PROTOCOL_INFORMATION) CoreOpenProtocolInformation, // OpenProtocolInformation
(EFI_PROTOCOLS_PER_HANDLE) CoreProtocolsPerHandle, // ProtocolsPerHandle
(EFI_LOCATE_HANDLE_BUFFER) CoreLocateHandleBuffer, // LocateHandleBuffer
(EFI_LOCATE_PROTOCOL) CoreLocateProtocol, // LocateProtocol
(EFI_INSTALL_MULTIPLE_PROTOCOL_INTERFACES) CoreInstallMultipleProtocolInterfaces, // InstallMultipleProtocolInterfaces
(EFI_UNINSTALL_MULTIPLE_PROTOCOL_INTERFACES) CoreUninstallMultipleProtocolInterfaces, // UninstallMultipleProtocolInterfaces
(EFI_CALCULATE_CRC32) CoreEfiNotAvailableYetArg3, // CalculateCrc32
(EFI_COPY_MEM) CopyMem, // CopyMem
(EFI_SET_MEM) SetMem, // SetMem
(EFI_CREATE_EVENT_EX) CoreCreateEventEx // CreateEventEx
};
这里初始化定义的mBootServices地址会被直接传递给SystemTable：
EFI_SYSTEM_TABLE mEfiSystemTableTemplate = {
......
&mBootServices, // BootServices
......
};
运行时服务（RunTime Services）
在ExitBootServices执行之后，Boot Service中的函数就不能在使用了，但是Runtime Service Table中的函数仍然可以使用，从DXE阶段开始，一直到操作系统的结束，Runtime Service是一直存在的，在OS中依然可以调用。
结构体也是定义在MdePkg/Include/Uefi/UefiSpec.h:
///
/// EFI Runtime Services Table.
///
typedef struct {
///
/// The table header for the EFI Runtime Services Table.
///
EFI_TABLE_HEADER Hdr;
//
// Time Services
//
EFI_GET_TIME GetTime;
EFI_SET_TIME SetTime;
EFI_GET_WAKEUP_TIME GetWakeupTime;
EFI_SET_WAKEUP_TIME SetWakeupTime;
//
// Virtual Memory Services
//
EFI_SET_VIRTUAL_ADDRESS_MAP SetVirtualAddressMap;
EFI_CONVERT_POINTER ConvertPointer;
//
// Variable Services
//
EFI_GET_VARIABLE GetVariable;
EFI_GET_NEXT_VARIABLE_NAME GetNextVariableName;
EFI_SET_VARIABLE SetVariable;
//
// Miscellaneous Services
//
EFI_GET_NEXT_HIGH_MONO_COUNT GetNextHighMonotonicCount;
EFI_RESET_SYSTEM ResetSystem;
//
// UEFI 2.0 Capsule Services
//
EFI_UPDATE_CAPSULE UpdateCapsule;
EFI_QUERY_CAPSULE_CAPABILITIES QueryCapsuleCapabilities;
//
// Miscellaneous UEFI 2.0 Service
//
EFI_QUERY_VARIABLE_INFO QueryVariableInfo;
} EFI_RUNTIME_SERVICES;
默认的初始化变量定义在MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c:
EFI_RUNTIME_SERVICES mEfiRuntimeServicesTableTemplate = {
{
EFI_RUNTIME_SERVICES_SIGNATURE, // Signature
EFI_RUNTIME_SERVICES_REVISION, // Revision
sizeof (EFI_RUNTIME_SERVICES), // HeaderSize
0, // CRC32
0 // Reserved
},
(EFI_GET_TIME) CoreEfiNotAvailableYetArg2, // GetTime
(EFI_SET_TIME) CoreEfiNotAvailableYetArg1, // SetTime
(EFI_GET_WAKEUP_TIME) CoreEfiNotAvailableYetArg3, // GetWakeupTime
(EFI_SET_WAKEUP_TIME) CoreEfiNotAvailableYetArg2, // SetWakeupTime
(EFI_SET_VIRTUAL_ADDRESS_MAP) CoreEfiNotAvailableYetArg4, // SetVirtualAddressMap
(EFI_CONVERT_POINTER) CoreEfiNotAvailableYetArg2, // ConvertPointer
(EFI_GET_VARIABLE) CoreEfiNotAvailableYetArg5, // GetVariable
(EFI_GET_NEXT_VARIABLE_NAME) CoreEfiNotAvailableYetArg3, // GetNextVariableName
(EFI_SET_VARIABLE) CoreEfiNotAvailableYetArg5, // SetVariable
(EFI_GET_NEXT_HIGH_MONO_COUNT) CoreEfiNotAvailableYetArg1, // GetNextHighMonotonicCount
(EFI_RESET_SYSTEM) CoreEfiNotAvailableYetArg4, // ResetSystem
(EFI_UPDATE_CAPSULE) CoreEfiNotAvailableYetArg3, // UpdateCapsule
(EFI_QUERY_CAPSULE_CAPABILITIES) CoreEfiNotAvailableYetArg4, // QueryCapsuleCapabilities
(EFI_QUERY_VARIABLE_INFO) CoreEfiNotAvailableYetArg4 // QueryVariableInfo
};Runtime Services也是在DxeMain.c中被加入到System Table的：
//
// Allocate the EFI System Table and EFI Runtime Service Table from EfiRuntimeServicesData
// Use the templates to initialize the contents of the EFI System Table and EFI Runtime Services Table
//
gDxeCoreST = AllocateRuntimeCopyPool (sizeof (EFI_SYSTEM_TABLE), &mEfiSystemTableTemplate);
ASSERT (gDxeCoreST != NULL);
gDxeCoreRT = AllocateRuntimeCopyPool (sizeof (EFI_RUNTIME_SERVICES), &mEfiRuntimeServicesTableTemplate);
ASSERT (gDxeCoreRT != NULL);
gDxeCoreST->RuntimeServices = gDxeCoreRT;
//上面的初始化定义中，很多回调函数被设置为了CoreEfiNotAvailableYet*，这说明此函数还不可用，需要在DXE运行阶段动态的添加进来的。