Step to UEFI (101）Application 驻留内存

前面一篇文章提到“提供服务的代码需要常驻内存，一般的 Application 是不会常驻内存的，而驱动直接可以常驻内存”。普通的Application 不能常驻内存，但是可以做个特殊的Application 来完成这个功能，之前的文章【参考1】我们尝试过写一个能够一直在 Shell 右上角显示当前时间的程序。结合前面的Protocol安装的驱动代码，我们做一个安装Protocol的Application。

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

#include  <stdio.h>
#include  <stdlib.h>
#include  <wchar.h>
#include  <time.h>
#include <Protocol/EfiShell.h>
#include <Library/ShellLib.h>
#include <Library/PrintLib.h>
#include <Protocol/SimpleFileSystem.h>
#include <Protocol/BlockIo.h>
#include <Library/DevicePathLib.h>
#include <Library/HandleParsingLib.h>
#include <Library/SortLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Protocol/LoadedImage.h>

#include "Print9.h"

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

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; 
} LOADED_IMAGE_PRIVATE_DATA_TEMP;

EFI_GUID gEfiPrint9ProtocolGuid=
	{ 0xf05976ef, 0x83f1, 0x4f3d, 
	{ 0x86, 0x19, 0xf7, 0x59, 0x5d, 0x41, 0xe5, 0x61 } };

#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)

CONST EFI_PRINT9_PROTOCOL mPrint9Protocol = {
  UnicodeBSPrint,
  UnicodeSPrint,
  UnicodeBSPrintAsciiFormat,
  UnicodeSPrintAsciiFormat,
  UnicodeValueToString,
  AsciiBSPrint,
  AsciiSPrint,
  AsciiBSPrintUnicodeFormat,
  AsciiSPrintUnicodeFormat,
  AsciiValueToString
};

EFI_LOADED_IMAGE_PROTOCOL          *ImageInfo = NULL;
  
typedef void (*Fun)();

void function()
{
  EFI_STATUS  Status;

  Status = gBS->InstallMultipleProtocolInterfaces (
                  &gImageHandle,
                  &gEfiPrint9ProtocolGuid, 
				  &mPrint9Protocol,
                  NULL
                  );
  ASSERT_EFI_ERROR (Status);
}


int
EFIAPI
main (                                         
  IN int Argc,
  IN char **Argv
  )
{
  EFI_STATUS                         Status = EFI_SUCCESS;
  EFI_HANDLE                         Handle = 0;
  EFI_GUID                           gEfiLoadedImageProtocolGuid = 
                                     { 0x5B1B31A1, 0x9562, 0x11D2, { 0x8E, 0x3F, 0x00, 0xA0, 0xC9, 0x69, 0x72, 0x3B }};
  LOADED_IMAGE_PRIVATE_DATA_TEMP      *private = NULL;
  Fun                                fun;
  UINTN                              FunOffset;
  UINTN                              FunAddr;

  Status = gBS->HandleProtocol (gImageHandle, &gEfiLoadedImageProtocolGuid, &ImageInfo);
  // function offset in the old image
  FunOffset = (UINTN)function - (UINTN)ImageInfo->ImageBase;

  // load the image in memory again
  Status = gBS->LoadImage(FALSE, gImageHandle, NULL, ImageInfo->ImageBase, (UINTN)ImageInfo->ImageSize, &Handle);  

  // get the newer imageinfo
  Status = gBS->HandleProtocol (Handle, &gEfiLoadedImageProtocolGuid, &ImageInfo);

  private = LOADED_IMAGE_PRIVATE_DATA_FROM_THIS(ImageInfo);
  FunAddr = (UINTN)FunOffset + (UINTN)ImageInfo->ImageBase;
  
  fun = (Fun)((UINTN)FunOffset + (UINTN)ImageInfo->ImageBase);
  // called the newer function in new image,the new image will be always in memory because it will not be free
  fun();
  return EFI_SUCCESS;
}

运行结果，和使用Driver方式的没有差别。

完整的代码下载：
appprotocol

参考：
1. https://www.lab-z.com/49str/ Step to UEFI (49） —– 内存驻留程序