EnableGop: Provide standalone GOP driver for EFI-era Macs

2025-12-08 19:25:01 +00:00 · 2023-01-23 05:52:09 +00:00 · 2023-01-23 05:52:09 +00:00 · f6bf1f2d86
commit f6bf1f2d86
parent b07843fe1d
19 changed files with 891 additions and 48 deletions
--- a/Changelog.md
+++ b/Changelog.md
@ -6,6 +6,8 @@ OpenCore Changelog
 - Added Linux support to legacy boot BootInstall script
 - Updated builtin firmware versions for SMBIOS and the rest
 - Fixed incomplete console mode initialisation when started in graphics mode
+- Provided additional UEFI forge mode, for use in firmware drivers
+- Implemented firmware driver enabling pre-OpenCore graphics on non-natively supported GPUs on EFI-era Macs

 #### v0.8.8
 - Updated underlying EDK II package to edk2-stable202211
--- a/Docs/Configuration.tex
+++ b/Docs/Configuration.tex
@ -3723,10 +3723,15 @@ the default boot entry choice will remain changed until the next manual reconfig

  \emph{Note 3}: On Macs with problematic GOP, it may be difficult to re-bless OpenCore if its bless status
  is lost. The \texttt{BootKicker} utility can be used to work around this problem, if set up as a Tool
-  in OpenCore (e.g. on a CDROM) with \texttt{FullNvramAccess} enabled. It will launch the Apple picker,
-  which allows selection of an item to boot next (with \texttt{Enter}), or next and subsequently, i.e.
-  as the blessed entry (with \texttt{CTRL+Enter}), as normal. After the selection is made, the system
-  will reboot and the chosen entry will be booted.
+  in OpenCore with \texttt{FullNvramAccess} enabled. It will launch the Apple picker,
+  which allows selection of an item to boot next (with \texttt{Enter}), or next and from then on until
+  the next change (with \texttt{CTRL+Enter}). Note that after the selection is made, the system
+  \emph{will reboot} before the chosen entry is booted. While this behaviour might seem surprising,
+  it can be used both to switch which OpenCore installation is blessed, with \texttt{CTRL+Enter},
+  e.g. from a recovery OpenCore installation on CD (selected with the \texttt{C} key on boot) back
+  to the main installion of OpenCore on the hard drive, if this is lost after an NVRAM reset. It can
+  also be used, even when the native picker cannot be shown normally (unsupported GPU), to do a one-shot
+  boot without OpenCore, e.g. to another OS or tool, or to an earlier version of macOS.

 \item
  \texttt{PickerVariant}\\
@ -6355,6 +6360,11 @@ even cause permanent firmware damage. Some of the known drivers are listed below
  any available writeable filesystem upon pressing \texttt{F10}.
  This is a modified version of \href{https://github.com/LongSoft/CrScreenshotDxe}{\texttt{CrScreenshotDxe}}
  driver by \href{https://github.com/NikolajSchlej}{Nikolaj Schlej}. \\
+\href{https://github.com/acidanthera/OpenCorePkg}{\texttt{EnableGop\{Direct\}}}\textbf{*}
+& Early beta release firmware-embeddable driver providing pre-OpenCore non-native GPU support
+  on MacPro5,1. Installation instructions can be found in the
+  \href{https://github.com/acidanthera/OpenCorePkg/blob/master/Staging/EnableGop/README.md}{\texttt{Utilities/EnableGop}}
+  directory of the OpenCore release zip file - proceed with caution. \\
 \href{https://github.com/acidanthera/OcBinaryData}{\texttt{ExFatDxe}}
 & Proprietary ExFAT file system driver for Bootcamp support commonly found in Apple
  firmware. For Sandy Bridge and earlier CPUs, the \texttt{ExFatDxeLegacy} driver should be
--- a/Include/Acidanthera/Library/OcBootManagementLib.h
+++ b/Include/Acidanthera/Library/OcBootManagementLib.h
@ -6,7 +6,8 @@
 #ifndef OC_BOOT_MANAGEMENT_LIB_H
 #define OC_BOOT_MANAGEMENT_LIB_H

-#include <Uefi.h>
+#include <PiDxe.h>
+#include <Guid/AppleVariable.h>
 #include <IndustryStandard/AppleBootArgs.h>
 #include <IndustryStandard/AppleHid.h>
 #include <Library/OcAppleBootPolicyLib.h>
@ -19,6 +20,8 @@
 #include <Protocol/LoadedImage.h>
 #include <Protocol/AppleBeepGen.h>
 #include <Protocol/OcAudio.h>
+#include <Protocol/GraphicsOutput.h>
+#include <Protocol/AppleUserInterface.h>

 #if defined (OC_TARGET_DEBUG) || defined (OC_TARGET_NOOPT)
 // #define BUILTIN_DEMONSTRATE_TYPING
@ -2075,6 +2078,17 @@ OcAddEntriesFromBootEntryProtocol (
  IN     BOOLEAN        CreateForHotKey
  );

+/**
+  Force Apple Firmware UI to always reconnect to current console GOP.
+
+  @retval EFI_SUCCESS   Firmware UI ConnectGop method was successfully reset.
+  @retval other         Compatible firmware UI protocol for reset could not be found.
+**/
+EFI_STATUS
+OcUnlockAppleFirmwareUI (
+  VOID
+  );
+
 /**
  Launch Apple boot picker firmware application.

--- a/Include/Acidanthera/Library/OcDeviceMiscLib.h
+++ b/Include/Acidanthera/Library/OcDeviceMiscLib.h
@ -73,11 +73,17 @@ OcPciInfoDump (
 /**
  Upgrade UEFI version to 2.x.

+  @param[in]      Forge     If TRUE forge, else just report status.
+  @param[in]      Trash     If TRUE trash gBS->CreateEventEx directly, else reallocate gBS.
+                            Reallocate strategy will only affect current image and any images
+                            it loads. Trash strategy should affect all images.
+
  @retval EFI_SUCCESS on success.
 **/
 EFI_STATUS
 OcForgeUefiSupport (
-  VOID
+  IN BOOLEAN  Forge,
+  IN BOOLEAN  Trash
  );

 /**
--- a/Library/OcBootManagementLib/OcBootManagementLib.c
+++ b/Library/OcBootManagementLib/OcBootManagementLib.c
@ -459,16 +459,30 @@ OcRunBootPicker (
  }
 }

+STATIC
+EFI_STATUS
+SetPickerEntryReason (
+  IN APPLE_PICKER_ENTRY_REASON  PickerEntryReason
+  )
+{
+  return gRT->SetVariable (
+                APPLE_PICKER_ENTRY_REASON_VARIABLE_NAME,
+                &gAppleVendorVariableGuid,
+                EFI_VARIABLE_BOOTSERVICE_ACCESS,
+                sizeof (PickerEntryReason),
+                &PickerEntryReason
+                );
+}
+
 EFI_STATUS
 OcRunFirmwareApplication (
  IN EFI_GUID  *ApplicationGuid,
  IN BOOLEAN   SetReason
  )
 {
-  EFI_STATUS                 Status;
-  EFI_HANDLE                 NewHandle;
-  EFI_DEVICE_PATH_PROTOCOL   *Dp;
-  APPLE_PICKER_ENTRY_REASON  PickerEntryReason;
+  EFI_STATUS                Status;
+  EFI_HANDLE                NewHandle;
+  EFI_DEVICE_PATH_PROTOCOL  *Dp;

  DEBUG ((DEBUG_INFO, "OCB: run fw app attempting to find %g...\n", ApplicationGuid));

@ -493,14 +507,7 @@ OcRunFirmwareApplication (

  if (!EFI_ERROR (Status)) {
    if (SetReason) {
-      PickerEntryReason = ApplePickerEntryReasonUnknown;
-      Status            = gRT->SetVariable (
-                                 APPLE_PICKER_ENTRY_REASON_VARIABLE_NAME,
-                                 &gAppleVendorVariableGuid,
-                                 EFI_VARIABLE_BOOTSERVICE_ACCESS,
-                                 sizeof (PickerEntryReason),
-                                 &PickerEntryReason
-                                 );
+      Status = SetPickerEntryReason (ApplePickerEntryReasonUnknown);
    }

    DEBUG ((
@ -524,14 +531,86 @@ OcRunFirmwareApplication (
  return Status;
 }

+//
+// Patching prolog of this function works on more similar era firmware
+// than assuming that mGopAlreadyConnected is located immediately after
+// protocol interface (which applies on MacPro5,1 v144.0.0.0.0 but not others).
+//
+// MacPro5,1 + some iMacs:
+//
+// sub     rsp, 28h
+// cmp     cs:mGopAlreadyConnected, 0   ///< Ignore offset of this var
+// jz      short loc_10004431
+// xor     eax, eax
+// jmp     short loc_1000446F           ///< Change this to no jump
+//
+STATIC CONST UINT8  ConnectGopPrologue[] = {
+  0x48, 0x83, 0xEC, 0x28, 0x80, 0x3D, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x74, 0x04, 0x33, 0xC0, 0xEB,
+  0x3E
+};
+
+STATIC CONST UINT8  ConnectGopPrologueMask[] = {
+  0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00,
+  0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+  0xFF
+};
+
+STATIC CONST UINT8  ConnectGopReplace[] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00
+};
+
+STATIC CONST UINT8  ConnectGopReplaceMask[] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0xFF
+};
+
+//
+// iMac11,1:
+//
+// push    rbx
+// sub     rsp, 30h
+// cmp     cs:byte_100065C8, 0
+// jz      short loc_10004077
+// xor     ebx, ebx
+// jmp     short loc_100040D1
+//
+
+STATIC CONST UINT8  AltConnectGopPrologue[] = {
+  0x48, 0x53, 0x48, 0x83, 0xEC, 0x30,
+  0x80, 0x3D, 0x00, 0x00, 0x00, 0x00,0x00,
+  0x74, 0x04, 0x33, 0xDB, 0xEB, 0x5A
+};
+
+STATIC CONST UINT8  AltConnectGopPrologueMask[] = {
+  0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+  0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,0xFF,
+  0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+};
+
+STATIC CONST UINT8  AltConnectGopReplace[] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+STATIC CONST UINT8  AltConnectGopReplaceMask[] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0xFF
+};
+
 EFI_STATUS
-OcLaunchAppleBootPicker (
+OcUnlockAppleFirmwareUI (
  VOID
  )
 {
  EFI_STATUS                              Status;
  APPLE_FIRMWARE_USER_INTERFACE_PROTOCOL  *FirmwareUI;
-  UINT8                                   *aGopAlreadyConnected;
+  UINT32                                  ReplaceCount;

  Status = gBS->LocateProtocol (
                  &gAppleFirmwareUserInterfaceProtocolGuid,
@ -540,11 +619,11 @@ OcLaunchAppleBootPicker (
                  );

  if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_INFO, "OC: Cannot locate FirmwareUI protocol - %r\n", Status));
+    DEBUG ((DEBUG_INFO, "OCB: Cannot locate FirmwareUI protocol - %r\n", Status));
  } else if (FirmwareUI->Revision != APPLE_FIRMWARE_USER_INTERFACE_PROTOCOL_REVISION) {
    DEBUG ((
      DEBUG_INFO,
-      "OC: Launch Apple picker incompatible FirmwareUI protocol revision %u != %u\n",
+      "OCB: Unlock FirmwareUI incompatible protocol revision %u != %u\n",
      FirmwareUI->Revision,
      APPLE_FIRMWARE_USER_INTERFACE_PROTOCOL_REVISION
      ));
@ -552,19 +631,63 @@ OcLaunchAppleBootPicker (
  }

  if (!EFI_ERROR (Status)) {
-    //
-    // Location of relevant byte variable within loaded driver.
-    //
-    aGopAlreadyConnected = (VOID *)((UINT8 *)FirmwareUI + sizeof (APPLE_FIRMWARE_USER_INTERFACE_PROTOCOL));
+    ReplaceCount = ApplyPatch (
+                     ConnectGopPrologue,
+                     ConnectGopPrologueMask,
+                     sizeof (ConnectGopPrologue),
+                     ConnectGopReplace,
+                     ConnectGopReplaceMask,
+                     (VOID *)FirmwareUI->ConnectGop,
+                     sizeof (ConnectGopPrologue),
+                     1,
+                     0
+                     );

-    if (*aGopAlreadyConnected != 1) {
-      DEBUG ((DEBUG_WARN, "OC: Cannot force reconnect Apple GOP %u\n", *aGopAlreadyConnected));
-    } else {
-      *aGopAlreadyConnected = 0;
-      DEBUG ((DEBUG_INFO, "OC: Force reconnect Apple GOP\n"));
+    if (ReplaceCount == 0) {
+      ReplaceCount = ApplyPatch (
+                       AltConnectGopPrologue,
+                       AltConnectGopPrologueMask,
+                       sizeof (AltConnectGopPrologue),
+                       AltConnectGopReplace,
+                       AltConnectGopReplaceMask,
+                       (VOID *)FirmwareUI->ConnectGop,
+                       sizeof (AltConnectGopPrologue),
+                       1,
+                       0
+                       );
    }
+
+    Status = EFI_SUCCESS;
+    if (ReplaceCount == 0) {
+      Status = EFI_NOT_FOUND;
+      DEBUG ((
+        DEBUG_INFO,
+        "OCB: 0x%016LX 0x%016LX 0x%016LX\n",
+        *((UINT64 *)((UINT8 *)FirmwareUI->ConnectGop)),
+        *((UINT64 *)(((UINT8 *)FirmwareUI->ConnectGop) + 8)),
+        *((UINT64 *)(((UINT8 *)FirmwareUI->ConnectGop) + 16))
+        ));
+    }
+
+    DEBUG ((
+      EFI_ERROR (Status) ? DEBUG_WARN : DEBUG_INFO,
+      "OCB: FirmwareUI ConnectGop patch - %r\n",
+      Status
+      ));
  }

+  return Status;
+}
+
+EFI_STATUS
+OcLaunchAppleBootPicker (
+  VOID
+  )
+{
+  EFI_STATUS  Status;
+
+  OcUnlockAppleFirmwareUI ();
+
  Status = OcRunFirmwareApplication (&gAppleBootPickerFileGuid, TRUE);

  return Status;
--- a/Library/OcDeviceMiscLib/ForgeUefi.c
+++ b/Library/OcDeviceMiscLib/ForgeUefi.c
@ -1,6 +1,6 @@
 /** @file
  Copyright (c) 2020, joevt. All rights reserved.
-  Copyright (C) 2021, vit9696. All rights reserved.
+  Copyright (C) 2021-2023, vit9696, mikebeaton. All rights reserved.

  All rights reserved.

@ -13,13 +13,14 @@
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 **/

-#include <Uefi.h>
+#include <PiDxe.h>

 #include <Guid/EventGroup.h>

 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
+#include <Library/DxeServicesTableLib.h>
 #include <Library/IoLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/OcDeviceMiscLib.h>
@ -67,23 +68,46 @@ OcCreateEventEx (
  return EFI_SUCCESS;
 }

+//
+// The Trash strategy relies on old Apple firmware allocating gBS and gDS consecutively.
+// This layout is directly inherited from standard edk EFI code.
+// The strategy trashes the DXE_SERVICES_SIGNATURE value in gDS->Hdr.Signature, which
+// happily is only used when the memory is being loaded (when we check for references
+// to DXE_SERVICES_SIGNATURE throughout the edk code).
+// For the Trash strategy to work, we are required to trash exactly that QWORD of memory,
+// but in the targeted firmware we can confirm that it is harmless to do so before proceeding.
+//
 EFI_STATUS
 OcForgeUefiSupport (
-  VOID
+  IN BOOLEAN  Forge,
+  IN BOOLEAN  Trash
  )
 {
  EFI_BOOT_SERVICES  *NewBS;

  DEBUG ((
    DEBUG_INFO,
-    "OCDM: Found 0x%X UEFI version (%u bytes, rebuilding to %u)\n",
+    "OCDM: Found 0x%X/0x%X UEFI version (%u bytes, %u %a to %u) gST %p gBS %p gBS->CreateEventEx %p &gBS %p\n",
    gST->Hdr.Revision,
+    gBS->Hdr.Revision,
    gBS->Hdr.HeaderSize,
-    (UINT32)sizeof (EFI_BOOT_SERVICES)
+    Forge,
+    Trash ? "trashing" : "rebuilding",
+    (UINT32)sizeof (EFI_BOOT_SERVICES),
+    gST,
+    gBS,
+    gBS->CreateEventEx,
+    &gBS
    ));

+  if (!Forge) {
+    return EFI_SUCCESS;
+  }
+
  //
  // Already too new.
+  // This check will replace any earlier forge to 2.0 <= UEFI < 2.3.
+  // This is desirable in some cases and harmless in others.
  //
  if (gST->Hdr.Revision >= EFI_2_30_SYSTEM_TABLE_REVISION) {
    return EFI_ALREADY_STARTED;
@ -93,13 +117,29 @@ OcForgeUefiSupport (
    return EFI_INVALID_PARAMETER;
  }

-  NewBS = AllocateZeroPool (sizeof (EFI_BOOT_SERVICES));
-  if (NewBS == NULL) {
-    DEBUG ((DEBUG_INFO, "OCDM: Failed to allocate BS copy\n"));
-    return EFI_OUT_OF_RESOURCES;
-  }
+  if (Trash) {
+    if ((VOID *)&gBS->CreateEventEx != (VOID *)gDS) {
+      DEBUG ((
+        DEBUG_WARN,
+        "OCDM: Aborting trash strategy, gDS does not follow gBS\n"
+        ));
+      return EFI_UNSUPPORTED;
+    }

-  CopyMem (NewBS, gBS, gBS->Hdr.HeaderSize);
+    DEBUG ((
+      DEBUG_INFO,
+      "OCDM: Trashing gDS->Hdr.Signature with gBS->CreateEventEx\n"
+      ));
+    NewBS = gBS;
+  } else {
+    NewBS = AllocateZeroPool (sizeof (EFI_BOOT_SERVICES));
+    if (NewBS == NULL) {
+      DEBUG ((DEBUG_INFO, "OCDM: Failed to allocate BS copy\n"));
+      return EFI_OUT_OF_RESOURCES;
+    }
+
+    CopyMem (NewBS, gBS, gBS->Hdr.HeaderSize);
+  }

  NewBS->CreateEventEx  = OcCreateEventEx;
  NewBS->Hdr.HeaderSize = sizeof (EFI_BOOT_SERVICES);
@ -113,5 +153,10 @@ OcForgeUefiSupport (
  gST->Hdr.CRC32    = 0;
  gST->Hdr.CRC32    = CalculateCrc32 (gST, gST->Hdr.HeaderSize);

+  if (Trash) {
+    gDS->Hdr.CRC32 = 0;
+    gDS->Hdr.CRC32 = CalculateCrc32 (gDS, gDS->Hdr.HeaderSize);
+  }
+
  return EFI_SUCCESS;
 }
--- a/Library/OcDeviceMiscLib/OcDeviceMiscLib.inf
+++ b/Library/OcDeviceMiscLib/OcDeviceMiscLib.inf
@ -62,6 +62,7 @@
  PrintLib
  UefiLib
  UefiBootServicesTableLib
+  DxeServicesTableLib

 [Sources]
  ActivateHpetSupport.c
--- a/Library/OcMainLib/OpenCoreUefi.c
+++ b/Library/OcMainLib/OpenCoreUefi.c
@ -939,9 +939,7 @@ OcLoadUefiSupport (
    OcInstallPermissiveSecurityPolicy ();
  }

-  if (Config->Uefi.Quirks.ForgeUefiSupport) {
-    OcForgeUefiSupport ();
-  }
+  OcForgeUefiSupport (Config->Uefi.Quirks.ForgeUefiSupport, FALSE);

  if (Config->Uefi.Quirks.ReloadOptionRoms) {
    OcReloadOptionRoms ();
--- a/OpenCorePkg.dec
+++ b/OpenCorePkg.dec
@ -744,6 +744,12 @@
  ## @Prompt Use Pin Capabilities to identify audio outputs.
  gOpenCorePkgTokenSpaceGuid.PcdAudioControllerUsePinCapsForOutputs|TRUE|BOOLEAN|0x00000008

+  ## Indicates whether to build EnableGop driver with DirectGopRendering.<BR><BR>
+  ##   TRUE  - DirectGopRendering will be used.<BR>
+  ##   FALSE - DirectGopRendering will not be used.<BR>
+  ## @Prompt Use DirectGopRendering.
+  gOpenCorePkgTokenSpaceGuid.PcdEnableGopDirect|FALSE|BOOLEAN|0x00000009
+
 [PcdsFixedAtBuild]
  ## Defines the Console Control initialization mode set on entry.<BR><BR>
  ##   0 - EfiConsoleControlScreenText<BR>
--- a/OpenCorePkg.dsc
+++ b/OpenCorePkg.dsc
@ -22,6 +22,7 @@
  BUILD_TARGETS           = RELEASE|DEBUG|NOOPT
  SKUID_IDENTIFIER        = DEFAULT
  DSC_SPECIFICATION       = 0x00010006
+  FLASH_DEFINITION        = OpenCorePkg/OpenCorePkg.fdf

  #
  # Network definition
@ -319,6 +320,14 @@
  OpenCorePkg/Platform/ResetNvramEntry/ResetNvramEntry.inf
  OpenCorePkg/Platform/ToggleSipEntry/ToggleSipEntry.inf
  OpenCorePkg/Staging/AudioDxe/AudioDxe.inf
+  OpenCorePkg/Staging/EnableGop/EnableGop.inf {
+    <LibraryClasses>
+      DebugLib|OpenCorePkg/Library/OcDebugLibNull/OcDebugLibNull.inf
+  }
+  OpenCorePkg/Staging/EnableGop/EnableGopDirect.inf {
+    <LibraryClasses>
+      DebugLib|OpenCorePkg/Library/OcDebugLibNull/OcDebugLibNull.inf
+  }
  OpenCorePkg/Staging/OpenHfsPlus/OpenHfsPlus.inf
  OpenCorePkg/Tests/AcpiTest/AcpiTest.inf
  OpenCorePkg/Tests/AcpiTest/AcpiTestApp.inf
--- a/OpenCorePkg.fdf
+++ b/OpenCorePkg.fdf
@ -0,0 +1,105 @@
+## @file
+#  Compile standalone firmware filesystem files.
+#
+#  Copyright (C) 2022-2023, Mike Beaton. All rights reserved.<BR>
+#  SPDX-License-Identifier: BSD-3-Clause
+##
+
+#
+# For now disable non-64-bit build; Mac Pro cannot use it, and EDK-II
+# build system does not separate 64 bit and 32 bit .ffs files, which
+# we want to distribute.
+#
+# If we needed all archs in future we could distribute the complete
+# .fv files, from which the .ffs can be re-extracted.
+#
+!if ($(ARCH) == X64)
+
+!if ($(ARCH) == X64)
+  [FV.FfsFilesX64]
+!else
+  [FV.FfsFilesIA32]
+!endif
+
+  BlockSize          = 0x10000
+  NumBlocks          = 8
+  FvAlignment        = 16         #FV alignment and FV attributes setting.
+  ERASE_POLARITY     = 1
+  MEMORY_MAPPED      = TRUE
+  STICKY_WRITE       = TRUE
+  LOCK_CAP           = TRUE
+  LOCK_STATUS        = TRUE
+  WRITE_DISABLED_CAP = TRUE
+  WRITE_ENABLED_CAP  = TRUE
+  WRITE_STATUS       = TRUE
+  WRITE_LOCK_CAP     = TRUE
+  WRITE_LOCK_STATUS  = TRUE
+  READ_DISABLED_CAP  = TRUE
+  READ_ENABLED_CAP   = TRUE
+  READ_STATUS        = TRUE
+  READ_LOCK_CAP      = TRUE
+  READ_LOCK_STATUS   = TRUE
+
+  #
+  # DXE Drivers (other .inf files for conversion to .ffs may be added here)
+  #
+  INF  OpenCorePkg/Staging/EnableGop/EnableGop.inf
+
+!if ($(ARCH) == X64)
+  [FV.EnableGopDirectX64]
+!else
+  [FV.EnableGopDirectIA32]
+!endif
+
+  BlockSize          = 0x10000
+  NumBlocks          = 8
+  FvAlignment        = 16         #FV alignment and FV attributes setting.
+  ERASE_POLARITY     = 1
+  MEMORY_MAPPED      = TRUE
+  STICKY_WRITE       = TRUE
+  LOCK_CAP           = TRUE
+  LOCK_STATUS        = TRUE
+  WRITE_DISABLED_CAP = TRUE
+  WRITE_ENABLED_CAP  = TRUE
+  WRITE_STATUS       = TRUE
+  WRITE_LOCK_CAP     = TRUE
+  WRITE_LOCK_STATUS  = TRUE
+  READ_DISABLED_CAP  = TRUE
+  READ_ENABLED_CAP   = TRUE
+  READ_STATUS        = TRUE
+  READ_LOCK_CAP      = TRUE
+  READ_LOCK_STATUS   = TRUE
+
+  #
+  # DXE Drivers
+  #
+
+  #
+  # EnableGopDirect intentionally has the same GUID as EnableGop, so it must go in a separate FV.
+  # (We don't care about the FV, rather the intermediate FFS files which are generated during build.)
+  #
+  INF  OpenCorePkg/Staging/EnableGop/EnableGopDirect.inf
+
+!endif
+
+#
+# Ideally we would match the compressed layout of DXE drivers in Mac Pro 144.0.0.0.0 firmware,
+# as per the commented out lines, but Mac Pro will not load this with standard compression.
+# With lines commented out we make a different, non-compressed layout which the Mac Pro will load.
+#
+# TODO: Is there a way to make a Tiano-compressed COMPRESS section, as in Mac Pro firmware, using
+# EDK-II build tools? If we manually reconstuct one with UEFITool 0.25.1, Mac Pro will load it.
+#
+# Note: `GUIDED A31280AD-481E-41B6-95E8-127F4C984779` will make a Tiano compressed GUIDED
+# section, but this is different and 144.0.0.0.0 will not load it.
+#
+[Rule.Common.DXE_DRIVER]
+  FILE DRIVER = $(NAMED_GUID) Checksum {
+#    COMPRESS {
+#      GUIDED {
+        DXE_DEPEX    DXE_DEPEX Optional      $(INF_OUTPUT)/$(MODULE_NAME).depex
+        PE32         PE32                    $(INF_OUTPUT)/$(MODULE_NAME).efi
+        UI           STRING="$(MODULE_NAME)" Optional
+#      }
+#    }
+  }
--- a/Staging/EnableGop/EnableGop.c
+++ b/Staging/EnableGop/EnableGop.c
@ -0,0 +1,132 @@
+/** @file
+  Provide GOP on unsupported graphics cards on EFI-era MacPro and iMac.
+
+  Copyright (c) 2022-2023, Mike Beaton. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-3-Clause
+**/
+
+#include <Uefi.h>
+
+#include <Library/DxeServicesTableLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+#include <Library/OcBootManagementLib.h>
+#include <Library/OcConsoleLib.h>
+#include <Library/OcDeviceMiscLib.h>
+
+STATIC EFI_GET_MEMORY_SPACE_MAP  mOriginalGetMemorySpaceMap;
+
+//
+// Equivalent to a very cut down OcLoadUefiOutputSupport.
+//
+STATIC
+EFI_STATUS
+LoadUefiOutputSupport (
+  VOID
+  )
+{
+  EFI_STATUS  Status;
+
+  Status = OcProvideConsoleGop (FALSE);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  OcSetConsoleResolution (
+    0,
+    0,
+    0,
+    FALSE
+    );
+
+  if (FeaturePcdGet (PcdEnableGopDirect)) {
+    OcUseDirectGop (-1);
+  }
+
+  OcSetupConsole (
+    OcConsoleRendererBuiltinGraphics,
+    FALSE,
+    FALSE,
+    FALSE,
+    FALSE
+    );
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+ProvideGop (
+  VOID
+  )
+{
+  OcUnlockAppleFirmwareUI ();
+
+  return LoadUefiOutputSupport ();
+}
+
+//
+// This memory map access happens twice during PlatformBdsPolicyBehavior, once
+// in the equivalent of efi InitializeMemoryTest at the start of the function,
+// and once during PlatformBdsDiagnostics, slightly later. The second call(s)
+// (there is more than one code path, depending on the boot type) are after
+// the default console has been connected, and therefore ideal for us.
+//
+EFI_STATUS
+EFIAPI
+WrappedGetMemorySpaceMap (
+  OUT UINTN                            *NumberOfDescriptors,
+  OUT EFI_GCD_MEMORY_SPACE_DESCRIPTOR  **MemorySpaceMap
+  )
+{
+  STATIC UINTN  mGetMemorySpaceMapAccessCount = 0;
+
+  mGetMemorySpaceMapAccessCount++;
+
+  if (mGetMemorySpaceMapAccessCount == 2) {
+    ProvideGop ();
+  }
+
+  return mOriginalGetMemorySpaceMap (
+           NumberOfDescriptors,
+           MemorySpaceMap
+           );
+}
+
+STATIC
+VOID
+WrapGetMemorySpaceMap (
+  VOID
+  )
+{
+  mOriginalGetMemorySpaceMap = gDS->GetMemorySpaceMap;
+  gDS->GetMemorySpaceMap     = WrappedGetMemorySpaceMap;
+
+  gDS->Hdr.CRC32 = 0;
+  gBS->CalculateCrc32 (gDS, gDS->Hdr.HeaderSize, &gDS->Hdr.CRC32);
+}
+
+//
+// If we execute the entire console setup at Driver#### time then we have to forge UEFI, reload option ROMs
+// and connect them, all at that point.
+// This works on some systems but causes crashes others, or causes an empty picker with question mark folder.
+// Current strategy is:
+//  - Forge UEFI early; relatively easy: just do it immediately, as below, and insert this driver either
+//    a) anywhere in main firmware volume, or b) in VBIOS anywhere before GOP driver which needs it
+//  - Execute rest of payload after option roms have been loaded, _and_ after firmware has already connected
+//    them (see WrapGetMemorySpaceMap strategy above).
+// With this strategy we do not need to reload or reconnect any option ROMs, which is much more stable.
+//
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  OcForgeUefiSupport (TRUE, TRUE);
+  WrapGetMemorySpaceMap ();
+
+  return EFI_SUCCESS;
+}
--- a/Staging/EnableGop/EnableGop.inf
+++ b/Staging/EnableGop/EnableGop.inf
@ -0,0 +1,46 @@
+## @file
+#
+#  Provide GOP on unsupported graphics cards on EFI-era MacPro and iMac.
+#
+#  Copyright (c) 2022-2023, Mike Beaton. All rights reserved.
+#  SPDX-License-Identifier: BSD-3-Clause
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = EnableGop
+  FILE_GUID                      = 3FBA58B1-F8C0-41BC-ACD8-253043A3A17F
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  EnableGop.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OpenCorePkg/OpenCorePkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  DxeServicesTableLib
+  OcBootManagementLib
+  OcConsoleLib
+  OcDeviceMiscLib
+  UefiBootServicesTableLib
+  UefiDriverEntryPoint
+  UefiRuntimeServicesTableLib
+
+[FeaturePcd]
+  gOpenCorePkgTokenSpaceGuid.PcdEnableGopDirect|FALSE
+
+[Depex]
+  TRUE
--- a/Staging/EnableGop/EnableGopDirect.inf
+++ b/Staging/EnableGop/EnableGopDirect.inf
@ -0,0 +1,46 @@
+## @file
+#
+#  Provide GOP on unsupported graphics cards on EFI-era MacPro and iMac using DirectGopRendering.
+#
+#  Copyright (c) 2023, Mike Beaton. All rights reserved.
+#  SPDX-License-Identifier: BSD-3-Clause
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = EnableGopDirect
+  FILE_GUID                      = 3FBA58B1-F8C0-41BC-ACD8-253043A3A17F
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  EnableGop.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OpenCorePkg/OpenCorePkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  DxeServicesTableLib
+  OcBootManagementLib
+  OcConsoleLib
+  OcDeviceMiscLib
+  UefiBootServicesTableLib
+  UefiDriverEntryPoint
+  UefiRuntimeServicesTableLib
+
+[FeaturePcd]
+  gOpenCorePkgTokenSpaceGuid.PcdEnableGopDirect|TRUE
+
+[Depex]
+  TRUE
--- a/Staging/EnableGop/NvInsertEfi.sh
+++ b/Staging/EnableGop/NvInsertEfi.sh
@ -0,0 +1,117 @@
+#!/bin/bash
+
+#
+# Copyright © 2023 Mike Beaton. All rights reserved.
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# Insert EFI into Nvidia VBIOS.
+#
+# TODO: Check that original GOP is present, and locate it in the original file automatically.
+#
+
+usage() {
+  echo "Usage: ./${SELFNAME} {rom-file} {efi-file} {GOP offset} {out-file}"
+  echo "E.g.:"
+  echo "  ./${SELFNAME} nv.rom GOP.efi 0xFC00 mod.rom"
+  echo "  ./${SELFNAME} nv.rom GOP.efi 64512 mod.rom"
+  echo ""
+}
+
+SELFNAME="$(/usr/bin/basename "${0}")"
+
+if [ "$#" -ne 4 ] ; then
+  usage
+  exit 0
+fi
+
+commands=(
+  "EfiRom"
+  "UEFIRomExtract"
+)
+FOUND=1
+for command in "${commands[@]}"; do
+  if ! command -v "$command" 1>/dev/null ; then
+    echo "${command} not available!"
+    FOUND=0
+  fi
+done
+
+if [ "$FOUND" -eq 0 ] ; then
+  exit 1
+fi
+
+ROM_FILE="$1"
+EFI_FILE="$2"
+GOP_OFFSET="$3"
+OUT_FILE="$4"
+
+# https://unix.stackexchange.com/a/84980/340732
+tmpdir=$(mktemp -d 2>/dev/null || mktemp -d -t 'vbios') || exit 1
+
+echo "Splitting original ROM..."
+
+dd bs=1 if="$ROM_FILE" of="$tmpdir/original_first_part.rom" count=$(($GOP_OFFSET)) status=none || exit 1
+dd bs=1 if="$ROM_FILE" of="$tmpdir/original_last_part.rom" skip=$(($GOP_OFFSET)) status=none || exit 1
+
+echo "Compressing ${EFI_FILE} using EfiRom..."
+EfiRom -o "$tmpdir/insert.rom" -ec "$EFI_FILE" -f 0xAAAA -i 0xBBBB -l 0x30000 || exit 1
+
+echo "Adding Nvidia header..."
+dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_first_part" count=$((0x38)) status=none || exit 1
+dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_last_part" skip=$((0x38)) status=none || exit 1
+
+INSERT_SIZE=$(stat -f%z "$tmpdir/insert.rom") || exit 1
+
+# add NPDE from original GOP
+dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_first_part" skip=$((0x38)) seek=$((0x38)) count=$((0x18)) status=none || exit 1
+cat "$tmpdir/insert_first_part" "$tmpdir/insert_last_part" > "$tmpdir/insert_oversize.rom" || exit 1
+# `truncate` not present by default on macOS
+dd bs=1 if="$tmpdir/insert_oversize.rom" of="$tmpdir/insert_fixed.rom" count="$INSERT_SIZE" status=none || exit 1
+
+# patch size in NPDE
+dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x2)) seek=$((0x48)) count=1 conv=notrunc status=none || exit 1
+
+# patch with vendor and device id from original GOP
+dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x20)) seek=$((0x20)) count=4 conv=notrunc status=none || exit 1
+
+# patch size in PCIR
+dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x16)) seek=$((0x16)) count=1 conv=notrunc status=none || exit 1
+
+# patch end marker in NPDE in fixed ROM (leave PCIR correct and EFI extractable from fixed ROM)
+echo -n -e '\x00' | dd bs=1 of="$tmpdir/insert_fixed.rom" seek=$((0x4A)) conv=notrunc status=none || exit 1
+
+echo "Writing ${OUT_FILE}..."
+cat "$tmpdir/original_first_part.rom" "$tmpdir/insert_fixed.rom" "$tmpdir/original_last_part.rom" > "$OUT_FILE" || exit 1
+
+# patch end marker in PCIR in out file
+echo -n -e '\x00' | dd bs=1 of="$OUT_FILE" seek=$(($GOP_OFFSET + 0x31)) conv=notrunc status=none || exit 1
+
+echo "Verifying ${OUT_FILE}..."
+dd bs=1 if="$OUT_FILE" of="$tmpdir/out_efi_part.rom" skip=$(($GOP_OFFSET)) status=none || exit 1
+UEFIRomExtract "$tmpdir/out_efi_part.rom" "$tmpdir/extracted.efi" 1>/dev/null || exit 1
+ERROR=0
+diff "$tmpdir/extracted.efi" "$EFI_FILE" 1>/dev/null || ERROR=1
+
+if [ "$ERROR" -ne 0 ] ; then
+  echo " - Failure comparing extracted EFI to original!"
+fi
+
+OLD_EFI_COUNT=$(EfiRom -d "$tmpdir/original_last_part.rom" | grep "0x0EF1" | wc -l) || exit 1
+OLD_EFI_COUNT=$(($OLD_EFI_COUNT)) || exit 1
+
+NEW_EFI_COUNT=$(EfiRom -d "$tmpdir/out_efi_part.rom" | grep "0x0EF1" | wc -l) || exit 1
+NEW_EFI_COUNT=$(($NEW_EFI_COUNT)) || exit 1
+
+if [ "$NEW_EFI_COUNT" -ne $(($OLD_EFI_COUNT + 1)) ] ; then
+  echo " - Found ${NEW_EFI_COUNT} EFI parts, expected $(($OLD_EFI_COUNT + 1))!"
+fi
+
+if [ "$ERROR" -eq 0 ] ; then
+  echo "SUCCESS."
+else
+  echo "*** WARNING - FAIL ***"
+fi
+
+rm -rf "$tmpdir" || exit 1
+
+echo "Done."
--- a/Staging/EnableGop/README.md
+++ b/Staging/EnableGop/README.md
@ -0,0 +1,154 @@
+# Provides standalone GOP driver for EFI era Mac Pro and iMac
+
+## Status
+**Current status: Early beta release.**
+
+This driver has been tested and is working on several iMac models
+with several different GPUs, and on several MacPro4,1/5,1 machines with several different GPUs. However, in the worst
+case (and still quite possible) scenario, an incompatible or incorrectly installed driver
+in firmware may brick your hardware.
+
+*In all cases take a backup of the main firmware or VBIOS firmware which you are modifying, and confirm that
+you can successfully restore from this, before starting.*
+
+## Recovery from bricked hardware
+ - If attempting firmware insertion on a MacPro4,1/5,1, for recovery from a bricked device you will either
+need a Matt card (which may breach intellectual property laws in some jurisdictions) or the ability to
+desolder and reprogram your own NVRAM chip.
+ - If testing via firmware insertion on an iMac, you will need the ability to disassemble your iMac and
+reprogram its NVRAM chip using a SOIC clip attached to a CH341A controller running on another computer.
+ - If testing via VBIOS insertion (iMac or Mac Pro), you will need the ability to disassemble your system,
+likely remove the heat sink from the graphics card, and then reprogram its NVRAM chip using a SOIC
+clip attached to a CH341A controller running on another computer.
+   - If testing via VBIOS insertion, in some cases it may also be possible
+to use physical electrical connection to your GPU NVRAM chip in order to boot with no graphics, then connect
+to your machine with `ssh` (which must have been enabled beforehand) and reprogram the GPU NVRAM. Advice on
+this is not provided here, but may be found for instance on the iMac GPU related forum threads listed below.
+
+*If you are not familiar with the above procedures, you are strongly recommended to wait for further testing by
+users who are. No further help can be provided here, and you proceed entirely at your own risk.*
+
+## Summary
+Targetting EFI-era (~2009-2012) MacPro4,1/5,1 and iMac firmware, this driver gathers and injects the parts of
+OpenCore needed for pre-boot graphics support with non-natively supported GPUs.
+
+The requirements for using this driver are:
+
+ - EFI-era (~2009-2012) MacPro4,1/5,1 or iMac with most recent firmware.
+ - A GPU which does not produce native pre-boot graphics (such as native picker when pressing ALT key during boot)
+ before OpenCore starts (otherwise, you do not need it).
+ - A GPU which produces graphics when using OpenCore (this must include successfully showing the native Apple boot
+ picker when started via the latest version of OpenCore tool `BootKicker.efi`) (otherwise, the driver will not work).
+   - *Note*: If your OpenCore installation includes a required GOP driver for your graphics card (this is added
+   automatically on some systems by recent versions of OpenCore Legacy Patcher, as a way to enable OpenCore menu
+   in cards such as ex-mining GPUs), then you would also need to burn that driver to the VBIOS of your graphics
+   card in order to obtain pre-OpenCore graphics; instructions for this are outside the scope of this tutorial,
+   although the procedures required for modifying VBIOS are similar to what is covered here.
+
+When installed, the driver should enable:
+
+ - Native boot picker via ALT key
+ - Firmware password UI
+ - Target disk mode UI
+ - macOS boot progress screen
+ - etc.
+
+Compiled versions of the driver files and these instructions may be found in the `Utilities/EnableGop`
+directory of the OpenCore release package.
+
+For GPUs needing `DirectGopRendering` in OpenCore configuration, use `EnableGopDirect.efi`, otherwise use `EnableGop.efi`
+as it renders faster on most other systems.
+
+The driver may be installed to VBIOS or to main firmware. It is expected that most Mac Pro users will use firmware insertion
+and most iMac users will chose VBIOS insertion, however both techniques work on both systems (but it is harder to modify the
+iMac firmware).
+
+## Usage
+
+## Install to firmware
+
+For reading and writing to firmware on the Mac Pro, @Macschrauber's [Rom Dump](https://www.youtube.com/watch?v=q4NW00oyUKE) works
+well. Alternatively the kexts and executables which this uses can be sourced individually (or extracted from the Rom Dump app) and
+run from the command line.
+
+The firmware on the iMac cannot be updated without an initial hardware flash (SOIC clip plus CH341A controller), therefore
+the recommended approach on iMac systems is [VBIOS injection](#install-to-vbios). However, the below instructions for firmware
+injection do work, if you are willing to do a hardware flash of the resulting firmware file, or if you have already
+[unprotected your iMac firmware](https://forums.macrumors.com/threads/imac-2011-see-more-uefi-firmware-mod.2257435/page-3?post=31087001#post-31087001) -
+which reduces security, and is only recommended for those actively developing firmware modifications.
+
+The `.ffs` file provided in this directory can be manually added to the extracted firmware file using [`UEFITool`](https://github.com/LongSoft/UEFITool),
+or automatically added using @dosdude1's [`DXEInject`](https://dosdude1.com/apps/). Once more, if you are not familiar with these procedures,
+you are recommended to proceed with extreme caution.
+
+### Using DXEInject
+
+To install the driver via `DXEInject`, the command is:
+
+ - `DXEInject {original}.rom {modified}.rom EnableGop.ffs`
+
+The file `{modifed}.rom` is ready for burning, although the result can be checked using UEFITool, if required.
+
+> *Note*: If only reading a file with UEFITool, the latest version is recommended, as it provides the most information.
+For writing, the older version 0.25.1 must be used, as described below.
+
+### Using UEFITool
+
+The `.ffs` file may be inserted anywhere within the same firmware volume which contains `DuetBds`
+(file GUID `A6F691AC-31C8-4444-854C-E2C1A6950F92`). However, for simplicity, these instructions
+will insert it in the same place that `DXEInject` does:
+
+ - Use UEFITool 0.25.1 (it must be that old version, not the newer NE or new engine versions, which
+cannot yet edit)
+ - Perform a header-only GUID search for `BAE7599F-3C6B-43B7-BDF0-9CE07AA91AA6`
+ - Double-click on the search result
+ - Right-click on the DXE driver with that GUID which should then appear
+ - Choose "Insert after..." and select `EnableGop.ffs`
+ - Save the modified firmware
+
+The end result, after saving and re-loading, should look like this:
+
+<img src="UEFITool_Inserted_Screenshot.png">
+
+## Install to VBIOS
+
+Instructions and a script for inserting the driver into NVidia VBIOS are provided.
+Similar techniques are appropriate for AMD GPUs.
+
+For further information on VBIOS modification, see:
+
+ - https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/
+ - https://forums.macrumors.com/threads/imac-2011-maxwell-and-pascal-gpu-upgrade.2300989/
+ - https://github.com/Ausdauersportler/IMAC-EFI-BOOT-SCREEN/wiki
+ - https://winraid.level1techs.com/t/amd-and-nvidia-gop-update-no-requests-diy/30917
+
+### Nvidia
+
+To use the provided `NvInsertEfi.sh` script:
+
+ - Locate an appropriate version of the `nvflash` tool (avilable for Linux and Windows), which can be used to read
+ from and write to your Nvidia GPU VBIOS.
+ - Use `nvflash` to read a copy of your VBIOS.
+ - Using a hex editor, search in the VBIOS for the byte sequence `F1 0E 00 00` with the byte sequence `55 AA` coming
+ close before it; the start address of the `55 AA` is the value needed for the insertion offset in the next step.
+ - Run `./NvInsertEfi.Sh {original}.rom EnableGop.ffs {offset} {modified}/.rom`.
+   - Only if you modified a rom file obtained via `flashrom` rather than `nvflash`, you should manually truncate
+   the modified file's size to the original file's size at this point. (`nvflash` files only contain the used section
+   of the VBIOS, and therefore must not be truncated.)
+ - The new file `{modified}.rom` may be burnt to the VBIOS firmware.
+ 
+ Please note all the cautions already given above about the difficulty of recovering, unless you are familiar with
+ the procedures necessary, if this process fails.
+
+### AMD
+
+Similar procedures as for Nvidia apply.
+
+ - Further assistance and information may be available in the forums and pages listed above.
+
+## No longer supported: Install as Driver#### entry
+
+Early test versions of this driver included code to allow it to work when installed as a `Driver####` entry
+(`Driver####` entries do work when installed via `bcfg` and using MacPro4,1/5,1 firmware; they do not work on
+that firmware if using `efibootmgr`, and they are not supported by iMac firmware). This code has been removed
+in order to minimise the driver size for VBIOS insertion.
--- a/Staging/EnableGop/UEFITool_Inserted_Screenshot.png
+++ b/Staging/EnableGop/UEFITool_Inserted_Screenshot.png
--- a/Staging/README.md
+++ b/Staging/README.md
@ -1,8 +1,11 @@
 Staging drivers considered experimental and not production ready.

-## OpenHfsPlus
-This driver implements HFS+ support with bless extensions.
-
 ## AudioDxe
 Improved audio driver (currently only Intel HD audio).  
 HDMI or other digital outputs don't work.
+
+## EnableGop
+Standalone firmware-embeddable driver for non-native GPU support on EFI-era Mac Pro and iMac.
+
+## OpenHfsPlus
+This driver implements HFS+ support with bless extensions.
--- a/build_oc.tool
+++ b/build_oc.tool
@ -249,6 +249,32 @@ package() {
    fi
  done

+  # Copy Mac Pro GOP firmware driver.
+  mkdir -p "${dstdir}/Utilities/EnableGop" || exit 1
+  ENABLE_GOP_GUID="3FBA58B1-F8C0-41BC-ACD8-253043A3A17F"
+  ffsNames=(
+    "EnableGop"
+    "EnableGopDirect"
+    )
+  for ffsName in "${ffsNames[@]}"; do
+    cp "FV/Ffs/${ENABLE_GOP_GUID}${ffsName}/${ENABLE_GOP_GUID}.ffs" "${dstdir}/Utilities/EnableGop/${ffsName}.ffs" || exit 1
+  done
+  gopDrivers=(
+    "EnableGop.efi"
+    "EnableGopDirect.efi"
+    )
+  for file in "${gopDrivers[@]}"; do
+    cp "X64/${file}" "${dstdir}/Utilities/EnableGop"/ || exit 1
+  done
+  helpFiles=(
+    "README.md"
+    "UEFITool_Inserted_Screenshot.png"
+    "NvInsertEfi.sh"
+  )
+  for file in "${helpFiles[@]}"; do
+    cp "${selfdir}/Staging/EnableGop/${file}" "${dstdir}/Utilities/EnableGop"/ || exit 1
+  done
+
  utils=(
    "ACPIe"
    "acdtinfo"