Step to UEFI (51） —– EFI_Graphics_Output_Protocol获得基本信息

学习了一下如何获得 Shell 下当前的显示信息。通过 GraphicsOutputProtocol 来完成这个功能。这个 Protocol 在【参考1】 中有描述。

头定义在 \MdePkg\Include\Protocol\GraphicsOutput.h

typedef struct _EFI_GRAPHICS_OUTPUT_PROTOCOL EFI_GRAPHICS_OUTPUT_PROTOCOL;

///
/// Provides a basic abstraction to set video modes and copy pixels to and from 
/// the graphics controller's frame buffer. The linear address of the hardware 
/// frame buffer is also exposed so software can write directly to the video hardware.
///
struct _EFI_GRAPHICS_OUTPUT_PROTOCOL {
  EFI_GRAPHICS_OUTPUT_PROTOCOL_QUERY_MODE  QueryMode;
  EFI_GRAPHICS_OUTPUT_PROTOCOL_SET_MODE    SetMode;
  EFI_GRAPHICS_OUTPUT_PROTOCOL_BLT         Blt;
  ///
  /// Pointer to EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE data.
  ///
  EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE        *Mode;
};

从名称上来看，这个 Protocol 能够实现的功能是：查询/设置当前显示模式,将屏幕内容和内存互copy等。

这次实验的是查询功能。

查询的结果输出是 EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE 结构体

typedef struct {
  ///
  /// The number of modes supported by QueryMode() and SetMode().
  ///
  UINT32                                 MaxMode;
  ///
  /// Current Mode of the graphics device. Valid mode numbers are 0 to MaxMode -1.
  ///
  UINT32                                 Mode;
  ///
  /// Pointer to read-only EFI_GRAPHICS_OUTPUT_MODE_INFORMATION data.
  ///
  EFI_GRAPHICS_OUTPUT_MODE_INFORMATION   *Info;
  ///
  /// Size of Info structure in bytes.
  ///
  UINTN                                  SizeOfInfo;
  ///
  /// Base address of graphics linear frame buffer.
  /// Offset zero in FrameBufferBase represents the upper left pixel of the display.
  ///
  EFI_PHYSICAL_ADDRESS                   FrameBufferBase;
  ///
  /// Amount of frame buffer needed to support the active mode as defined by 
  /// PixelsPerScanLine xVerticalResolution x PixelElementSize.
  ///
  UINTN                                  FrameBufferSize;
} EFI_GRAPHICS_OUTPUT_PROTOCOL_MODE;

可以看到能够获得当前显示模式，屏幕分辨率和格式信息等。根据上面的信息，编写程序如下

#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 <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 <Protocol/LoadedImage.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;

static EFI_GUID GraphicsOutputProtocolGuid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
static EFI_GRAPHICS_OUTPUT_PROTOCOL *GraphicsOutput = NULL;

int
EFIAPI
main (                                         
  IN int Argc,
  IN char **Argv
  )
{
    EFI_STATUS Status;

    Status = gBS->LocateProtocol(&GraphicsOutputProtocolGuid, NULL, (VOID **) &GraphicsOutput);
    if (EFI_ERROR(Status)) {
        GraphicsOutput = NULL;
		Print(L"Loading Graphics_Output_Protocol error!\n");
		return EFI_SUCCESS;
	}	

	Print(L"Max mode     =[%d] \n",GraphicsOutput->Mode->MaxMode);
	Print(L"Current mode =[%d] \n",GraphicsOutput->Mode->Mode);
	Print(L"Version      =[%d] \n",GraphicsOutput->Mode->Info->Version);
	Print(L"Screen Width =[%d] \n",GraphicsOutput->Mode->Info->HorizontalResolution);
	Print(L"Screen height=[%d] \n",GraphicsOutput->Mode->Info->VerticalResolution);
	Print(L"Format       =[%d] \n",GraphicsOutput->Mode->Info->PixelFormat);
	Print(L"Num of pixel =[%d] \n",GraphicsOutput->Mode->Info->PixelsPerScanLine);
		
  return EFI_SUCCESS;
  
}

运行结果(还是NT32模拟器中)

完整代码下载：

GFXTest

参考：

1.UEFI Spec 2.4 P488 11.9 Graphics Output Protocol

==========================================================

2025年3月17日 额外同一个功能类似的代码

#include <Uefi.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Protocol/GraphicsOutput.h>
#include <Library/DebugLib.h>

INTN
EFIAPI
ShellAppMain (
  IN UINTN Argc,
  IN CHAR16 **Argv
)
{
  EFI_STATUS Status;
  EFI_GRAPHICS_OUTPUT_PROTOCOL *GraphicsOutput;
  UINTN HandleCount;
  EFI_HANDLE *HandleBuffer;
  UINTN Index;
  UINT32 ModeIndex;
  EFI_GRAPHICS_OUTPUT_MODE_INFORMATION *Info;
  UINTN SizeOfInfo;

  // Locate the handles that support the Graphics Output Protocol
  Status = gBS->LocateHandleBuffer(ByProtocol, &gEfiGraphicsOutputProtocolGuid, NULL, &HandleCount, &HandleBuffer);
  if (EFI_ERROR(Status)) {
    Print(L"Failed to locate handles for Graphics Output Protocol\n");
    return Status;
  }

  // Iterate over all handles
  for (Index = 0; Index < HandleCount; Index++) {
    // Get the Graphics Output Protocol instance
    Status = gBS->HandleProtocol(HandleBuffer[Index], &gEfiGraphicsOutputProtocolGuid, (VOID**)&GraphicsOutput);
    if (EFI_ERROR(Status)) {
      Print(L"Failed to handle protocol for handle %d\n", Index);
      continue;
    }
	Print(L"Controler [%d]\n", Index);
    // Iterate over each mode
    for (ModeIndex = 0; ModeIndex < GraphicsOutput->Mode->MaxMode; ModeIndex++) {
      // Get mode information
      Status = GraphicsOutput->QueryMode(GraphicsOutput, ModeIndex, &SizeOfInfo, &Info);
      if (EFI_ERROR(Status)) {
        Print(L"Failed to query mode %d\n", ModeIndex);
        continue;
      }

      // Output the resolution and pixel format
      Print(L"Mode %d: Resolution: %ux%u, Pixels Per Scanline: %u\n",
            ModeIndex,
            Info->HorizontalResolution,
            Info->VerticalResolution,
            Info->PixelsPerScanLine);

      // Free the mode information
      gBS->FreePool(Info);
    }
  }

  // Free the handle buffer
  gBS->FreePool(HandleBuffer);

  return EFI_SUCCESS;
}

## @file
#  A simple, basic, EDK II native, "hello" application.
#
#   Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
#   SPDX-License-Identifier: BSD-2-Clause-Patent
#
##

[Defines]
  INF_VERSION                    = 0x00010006
  BASE_NAME                      = gm
  FILE_GUID                      = a912f198-2025-0317-b908-b757b806ec83
  MODULE_TYPE                    = UEFI_APPLICATION
  VERSION_STRING                 = 0.1
  ENTRY_POINT                    = ShellCEntryLib

#
#  VALID_ARCHITECTURES           = IA32 X64
#

[Sources]
  GetModeInfo.c

[Packages]
  MdePkg/MdePkg.dec
  ShellPkg/ShellPkg.dec

[LibraryClasses]
  UefiLib
  ShellCEntryLib