分类： Other

前面【参考1】提到了 StartImage 加载 CLib 编写Application 出错的原因，这篇文章介绍如何解决这个问题。
根据原因来看是因为找不到提供 Parameters 的Protocol，那么我们在调用之前给被加载的Application 装上需要的Protocol即可。安装 Protocol 需要用到 InstallProtocollInterface，具体定义如下【参考2】：

欲安装的 Protocol 实例则是从加载程序（Exec6）上面取下来的。

没有多少人愿意看大篇幅的代码，我这里列下最关键的部分：

首先，取出当前的 Shell Interface, 不同的环境下还可以使用 Shell Parameter Protocol ， NT32 环境下只支持前者

//如果你在实体机上发现有问题，那么可以考虑这段代码的问题
  Status = gBS->OpenProtocol(gImageHandle,
                             &gEfiShellInterfaceGuid,
                             (VOID **)&EfiShellInterface,
                             gImageHandle,
                             NULL,
                             EFI_OPEN_PROTOCOL_GET_PROTOCOL
                            );
  if (EFI_ERROR(Status)) {
	Print(L"Shell Parameters Protocol not Found!\r\n",Status);	
    return (Status);	
  } 
//之后，将取下来的 Protocol 安装给被加载的 Application
  Status = gBS->InstallProtocolInterface (
            &NewHandle,
            &gEfiShellInterfaceGuid,
            EFI_NATIVE_INTERFACE,
            EfiShellInterface
           ); 
  if (EFI_ERROR(Status)) {
	Print(L"Protocol Interface Installed fail!\r\n",Status);
	return (Status);
  } 	

最后，安装之后不能忘记 Uninstall，还要调用一下，特别注意第一个参数传递的不是指针。

运行结果，可以看出 Hello1和 Hello2都可以被正常加载运行：

看到这里，这篇文章就可以结束了，下面列出 Exec6 的代码:

#include  <Uefi.h>
#include  <Library/UefiLib.h>
#include  <Library/ShellCEntryLib.h>

#include  <stdio.h>
#include  <stdlib.h>
#include  <wchar.h>

#include <Protocol/EfiShell.h>
#include <Library/ShellLib.h>

extern EFI_BOOT_SERVICES           	 *gBS;
extern EFI_SYSTEM_TABLE				 *gST;
extern EFI_RUNTIME_SERVICES 		 *gRT;

extern EFI_SHELL_PROTOCOL            *gEfiShellProtocol;
extern EFI_SHELL_ENVIRONMENT2 		 *mEfiShellEnvironment2;

extern EFI_HANDLE					 gImageHandle;

typedef struct {
  UINTN                       Signature;
  /// Image handle
  EFI_HANDLE                  Handle;   
  /// Image type
  UINTN                       Type;           
  /// If entrypoint has been called
  BOOLEAN                     Started;        
  /// The image's entry point
  EFI_IMAGE_ENTRY_POINT       EntryPoint;     
  /// loaded image protocol
  EFI_LOADED_IMAGE_PROTOCOL   Info; 
  /// Location in memory
  EFI_PHYSICAL_ADDRESS        ImageBasePage;    
} LOADED_IMAGE_PRIVATE_DATA_TEMP;

#define _CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) - (CHAR8 *) &(((TYPE *) 0)->Field)))

#define LOADED_IMAGE_PRIVATE_DATA_FROM_THIS(a) \
          _CR(a, LOADED_IMAGE_PRIVATE_DATA_TEMP, Info)
		  
/**
  GET  DEVICEPATH
**/
EFI_DEVICE_PATH_PROTOCOL *
EFIAPI
ShellGetDevicePath (
  IN CHAR16                     * CONST DeviceName OPTIONAL
  )
{
  //
  // Check for UEFI Shell 2.0 protocols
  //
  if (gEfiShellProtocol != NULL) {
    return (gEfiShellProtocol->GetDevicePathFromFilePath(DeviceName));
  }

  //
  // Check for EFI shell
  //
  if (mEfiShellEnvironment2 != NULL) {
    return (mEfiShellEnvironment2->NameToPath(DeviceName));
  }

  return (NULL);
}

int
EFIAPI
main (
  IN int Argc,
  IN CHAR16 **Argv
  )
{
  EFI_DEVICE_PATH_PROTOCOL *DevicePath;
  EFI_HANDLE	NewHandle;
  EFI_STATUS	Status;
  LOADED_IMAGE_PRIVATE_DATA_TEMP      *private = NULL;  
  UINTN			ExitDataSizePtr;
  EFI_LOADED_IMAGE_PROTOCOL	*ImageInfo = NULL;
    EFI_SHELL_INTERFACE           *EfiShellInterface=NULL;
	
  if (Argc!=2) {
		Print(L"Usage: Exec4 FileName\n");
		return EFI_SUCCESS;
  }
  
  Print(L"File [%s]\n",Argv[1]);

  DevicePath=ShellGetDevicePath(Argv[1]);

  //
  // Load the image with:
  // FALSE - not from boot manager and NULL, 0 being not already in memory
  //
  Status = gBS->LoadImage(
    FALSE,
    gImageHandle,
    DevicePath,
    NULL,
    0,
    &NewHandle);  

  if (EFI_ERROR(Status)) {
    if (NewHandle != NULL) {
      gBS->UnloadImage(NewHandle);
    }
	Print(L"Error during LoadImage [%X]\n",Status);
    return (Status);
  }

  Status = gBS -> HandleProtocol (
						NewHandle,
						&gEfiLoadedImageProtocolGuid,
						&ImageInfo
						);
						
  private = LOADED_IMAGE_PRIVATE_DATA_FROM_THIS(ImageInfo);  

  Print(L"ImageBase in EFI_LOADED_IMAGE_PROTOCOL      [%lX]\n",ImageInfo->ImageBase);
  Print(L"ImageBase in LOADED_IMAGE_PRIVATE_DATA_TEMP [%lX]\n",private->ImageBasePage);
  Print(L"Entry Point [%lX]\n",private->EntryPoint);
							  
  Status = gBS->OpenProtocol(gImageHandle,
                             &gEfiShellInterfaceGuid,
                             (VOID **)&EfiShellInterface,
                             gImageHandle,
                             NULL,
                             EFI_OPEN_PROTOCOL_GET_PROTOCOL
                            );
  if (EFI_ERROR(Status)) {
	Print(L"Shell Parameters Protocol not Found!\r\n",Status);	
    return (Status);	
  } 

  Status = gBS->InstallProtocolInterface (
            &NewHandle,
            &gEfiShellInterfaceGuid,
            EFI_NATIVE_INTERFACE,
            EfiShellInterface
           ); 
  if (EFI_ERROR(Status)) {
	Print(L"Protocol Interface Installed fail!\r\n",Status);
	return (Status);
  } 		   
 
  Print(L"================================RUN================================\r\n",Status);
 
  //
  // now start the image, passing up exit data if the caller requested it
  //
  Status = gBS->StartImage(
                     NewHandle,
                     &ExitDataSizePtr,
                     NULL
              );
  if (EFI_ERROR(Status)) {
    if (NewHandle != NULL) {
      gBS->UnloadImage(NewHandle);
    }
	Print(L"Error during StartImage [%X]\r\n",Status);
    return (Status);
  }

  Print(L"===============================EXIT================================\r\n",Status);

  Status = gBS->UninstallProtocolInterface (
            NewHandle,
            &gEfiShellInterfaceGuid,
            EfiShellInterface
           ); 
  if (EFI_ERROR(Status)) {
	Print(L"Protocol Interface Uninstalled fail!\r\n",Status);
	return (Status);
  } 
  
  gBS->UnloadImage (NewHandle);  

  Print(L"NewHandle [%lX]\n",NewHandle);  
  
  return EFI_SUCCESS;
}

完整代码下载：
exec6

至此，终于回答了 StartImage 执行Application 的问题，如果你发现本文有任何问题欢迎给我留言，或者你有什么其他问题，同样可以给我发 e-Mail。

就是这样。

参考：
1. http://www.lab-z.com/stu85/ StartImage CLib
2. Uefi Spec 2.4 P153