一、 编写源代码

1. 编写C:\edkii\OvmfPkg\MyHelloWorldInstallPPI\MyHelloWorldInstallPPI.c，

   #include <uefi.h>
   #include <Library/UefiLib.h>
   #include <Library/BaseLib.h>
   #include <Library/DebugLib.h>
   #include <Library/BaseMemoryLib.h>
   #include <Library/UefiDriverEntryPoint.h>
   #include <Library/PeimEntryPoint.h>
   #include <Library/PeiServicesLib.h>
   #include <Library/PeiServicesTablePointerLib.h>
   #include <Pi/PiHob.h>
   #include <Pi/PiPeiCis.h>
   
   EFI_GUID gMyHelloWorldPEIGUID = { 0xbdb38129, 0x4d65, 0x39f4, { 0x72, 0x12, 0x68, 0xcf, 0x5a, 0x19, 0xa, 0xf8 }};
   
   EFI_STATUS
   EFIAPI
   PrintHelloMsg (
     IN CHAR16 * Msg
     )
   {
     DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] PrintHelloMsg : %s \n",Msg));
     return EFI_SUCCESS;
   }
   
   typedef EFI_STATUS (EFIAPI * PRINTMSG)(CHAR16 *Msg);
   typedef struct _EFI_HELLOWORLD_PROTOCOL  {
       PRINTMSG PrintMsg;
   }EFI_HELLOWORLD_PROTOCOL;
   
   EFI_HELLOWORLD_PROTOCOL mHelloWorldPpi = {
       PrintHelloMsg
   };
   
   EFI_PEI_PPI_DESCRIPTOR     mPpiListCodePpi = {
     (EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
     &gMyHelloWorldPEIGUID,
     &mHelloWorldPpi
   };
   
   EFI_STATUS
   EFIAPI
   MyHelloWorldInstallPPIEntry(
     IN       EFI_PEI_FILE_HANDLE  FileHandle,
     IN CONST EFI_PEI_SERVICES     **PeiServices
   )
   {
     EFI_STATUS                              Status = EFI_SUCCESS;
     DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] MyHelloWorldInstallPPIEntry Start..\n"));
     PeiServicesInstallPpi  (&mPpiListCodePpi);
     DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] MyHelloWorldInstallPPIEntry End..\n"));
   
     return Status;
   }
   

2. 编写C:\edkii\OvmfPkg\MyHelloWorldInstallPPI\MyHelloWorldInstallPPI.inf，

   [Defines] 
     INF_VERSION = 0x00010006 
     BASE_NAME = MyHelloWorldInstallPPI 
     FILE_GUID = 69E6DE5D-F09E-485E-9936-EB70FDCFC82A
     MODULE_TYPE = PEIM
     VERSION_STRING = 1.0
     ENTRY_POINT = MyHelloWorldInstallPPIEntry 
     
   [Sources] 
     MyHelloWorldInstallPPI.c 
     
   [Packages]
     MdePkg/MdePkg.dec
     ShellPkg/ShellPkg.dec 
     MdeModulePkg/MdeModulePkg.dec
     
   [LibraryClasses]
     BaseLib
     PeimEntryPoint
     BaseMemoryLib
     DebugLib
     PeiServicesLib
     PrintLib
     #PeiLib
     #EfiCommonLib
   
   [depex]
     TRUE
   
   
   

3. 编写 C:\edkii\OvmfPkg\MyHelloWorldLocatePPI\MyHelloWorldLocatePPI.c

   #include <uefi.h>
   #include <Library/UefiLib.h>
   #include <Library/BaseLib.h>
   #include <Library/DebugLib.h>
   #include <Library/BaseMemoryLib.h>
   #include <Library/UefiDriverEntryPoint.h>
   #include <Library/PeimEntryPoint.h>
   #include <Library/PeiServicesLib.h>
   #include <Library/PeiServicesTablePointerLib.h>
   #include <Pi/PiHob.h>
   
   EFI_GUID gMyHelloWorldPEIGUID = { 0xbdb38129, 0x4d65, 0x39f4, { 0x72, 0x12, 0x68, 0xcf, 0x5a, 0x19, 0xa, 0xf8 }};
   
   
   typedef EFI_STATUS (EFIAPI * PRINTMSG)(CHAR16 *Msg);
   typedef struct _EFI_HELLOWORLD_PROTOCOL  {
       PRINTMSG PrintMsg;
   }EFI_HELLOWORLD_PROTOCOL;
   
   //ShellCEntryLib call user interface ShellAppMain
   EFI_STATUS
   EFIAPI
   MyHelloWorldLocatePPIEntry(
     IN       EFI_PEI_FILE_HANDLE  FileHandle,
     IN CONST EFI_PEI_SERVICES     **PeiServices
   )
   {
     EFI_STATUS  Status = EFI_SUCCESS;
     EFI_HELLOWORLD_PROTOCOL *mHelloWorldPpi = NULL;
     DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] MyHelloWorldLocatePPIEntry Locate PPI Start..\n"));
     Status = PeiServicesLocatePpi (
              &gMyHelloWorldPEIGUID,
              0,
              NULL,
              (VOID **)&mHelloWorldPpi
              );
     if (EFI_ERROR(Status)){
         DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] MyHelloWorldLocatePPIEntry Locate PPI Fail..%r\n",Status));
         return Status;
     }
     mHelloWorldPpi->PrintMsg(L"2019 CSDN Locate PPI Hello World ...\n");
     DEBUG ((EFI_D_ERROR, "[MyHelloWorldPPI] MyHelloWorldLocatePPIEntry Locate PPI End..\n"));
     return Status;
   }
   

4. 编写 C:\edkii\OvmfPkg\MyHelloWorldLocatePPI\MyHelloWorldLocatePPI.inf

   [Defines] 
     INF_VERSION = 0x00010006 
     BASE_NAME = MyHelloWorldLocatePPI 
     FILE_GUID = 69E6DE6D-F39F-485f-9037-EB70FDCFC82B
     MODULE_TYPE = PEIM
     VERSION_STRING = 1.0
     ENTRY_POINT = MyHelloWorldLocatePPIEntry 
     
   [Sources] 
     MyHelloWorldLocatePPI.c 
     
   [Packages]
     MdePkg/MdePkg.dec
     ShellPkg/ShellPkg.dec 
     MdeModulePkg/MdeModulePkg.dec
     
   [LibraryClasses]
     BaseLib
     PeimEntryPoint
     BaseMemoryLib
     DebugLib
     PeiServicesLib
     PrintLib
     #PeiLib
     #EfiCommonLib
   
   [depex]
     TRUE
   

5. 修改C:\edkii\OvmfPkg\OvmfPkgX64.dsc

   [Components]
   ...    
   #
   # PEI Phase modules
   #
   INF  OvmfPkg/MyHelloWorldInstallPPI/MyHelloWorldInstallPPI.inf
   INF  OvmfPkg/MyHelloWorldLocatePPI/MyHelloWorldLocatePPI.inf
   ...
   

   6. 修改C:\edkii\OvmfPkg\OvmfPkgX64.fdf

   [FV.PEIFV]
   ...
   #
   # PEI Phase modules
   #
   INF  OvmfPkg/MyHelloWorldInstallPPI/MyHelloWorldInstallPPI.inf
   INF  OvmfPkg/MyHelloWorldLocatePPI/MyHelloWorldLocatePPI.inf
   ...
   

二、 编译生成EFI文件

运行edksetup.bat编译整个OvmfPkg Package

三、 运行HelloWorld PPI Driver

1. 拷贝 C:\edkii\Build\OvmfX64\DEBUG_VS2013x86\FV\OVMF.fd 到C:\qemu
2. 执行setup-qemu-x64.bat | findstr MyHelloWorldPPI 的输出如下，
   

四、 小结

PPI(PEIM-to-PEIM Interface) 是一种PEIM驱动之间的通信方式，本文中MyHelloWorldInstallPPI模块通过PeiServicesInstallPpi提供了mPpiListCodePpi 服务，而MyHelloWorldLocatePPI模块通过PeiServicesLocatePpi获取了mPpiListCodePpi对象，通过访问对象的成员函数即可完成对驱动MyHelloWorldInstallPPI资源的访问。