功能描述

       由于开发需要，有时候需要在SBL阶段设置一些参数变量，然后给到系统启动之后读取操作

功能分析

       查看代码发现，高通默认有测试程序可以写共享内存，代码如下smem_test.c

./boot_images/boot/QcomPkg/QcomTestCommon/SmemTestApp/smem_test.c

#include <Uefi.h>
#include <Library/UefiLib.h>
#include <Library/UefiApplicationEntryPoint.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/TestInterface.h>
#include "Protocol/EFISmem.h"

EFI_STATUS
EFIAPI
UefiMain (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_SMEM_PROTOCOL * smem_protocol;
  EFI_STATUS status;

  UINT32 * vendor0;
  UINT32 * vendor1;
  UINT32 * vendor1_b;
  UINT32 * vendor1_c;
  UINT32 size;

  TEST_START("SMEM");

  status = gBS->LocateProtocol(&gEfiSMEMProtocolGuid, NULL,
      (void**)&smem_protocol);
  if(status != EFI_SUCCESS)
  {
    AsciiPrint("ERROR: LocateProtocol returned %d\n",