Add complete guide and all config variants

hackintosh-guide/Utilities/EnableGop/README.md

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+# Provides standalone GOP driver for EFI era Mac Pro and iMac
+
+## Releases
+
+EnableGop version (OpenCore version)
+
+### 1.4 (0.9.3)
+ - Incorporates recent updates to OpenCore console control code, but no difference in behaviour compared
+   to version 1.3 is expected on any supported systems.
+
+### 1.3 (0.9.2)
+ - Included fix to GopBurstMode for non-standard frame buffer information on AMD Radeon HD 7970 and similar
+ - Applied GopBurstMode even on natively supported cards, as it can provide a noticable speed up
+
+### 1.2 (0.9.1)
+ - Added GopBurstMode support
+
+*Note 1*: This should provide faster GOP rendering on all EnableGopDirect systems; and rendering at least at
+the same speed as before, and on some systems noticeably faster than before, on almost all EnableGop systems.
+
+*Note 2*: The compressed driver for version 1.2 is 1KB larger than for version 1.1, so for AMD GPU firmware which is
+tight on space version 1.1 may be used instead to avoid the need for VGA stripping to make additional space.
+
+### 1.1 (0.9.0)
+ - Fixed early verbose boot lines appearing over picker
+ - Added EnableGop version number to UI section
+
+### 1.0 (0.8.9)
+ - Initial public release
+
+## Status
+**Current status: 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 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 GPU firmware which you are modifying, and confirm that
+you can successfully restore from this, before starting.*
+
+## Recovery from bricked hardware
+ - If attempting main 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 SPI flash chip.
+ - If testing via main firmware insertion on an iMac, you will need the ability to disassemble your iMac and
+reprogram its SPI flash chip using a SOIC clip attached to a CH341A controller running on another computer.
+ - If testing via GPU firmware 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 SPI flash chip using a SOIC
+clip attached to a CH341A controller running on another computer.
+   - If testing via GPU firmware insertion, in some cases it may also be possible
+to use physical electrical connection to your GPU in order to enable booting with no graphics even though the GPU
+is present, then connect to your machine with `ssh` (which must have been enabled beforehand) and reprogram the GPU
+firmware. Advice on this headless boot approach 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 main 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, then you would
+   also need to burn that driver to the firmware 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
+   GPU firmware are similar to what is covered here.
+   Note that such a driver is added by the OCLP **Enable AMD GOP** option, which is enabled automatically on some
+   systems by recent versions of OpenCore Legacy Patcher, as a way to enable the OpenCore menu in cards such as ex-mining GPUs.
+
+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 GPU or main motherboard firmware. It is expected that most Mac Pro users will use main firmware insertion
+and most iMac users will chose GPU firmware insertion, however both techniques work on both systems (but it is harder to modify the
+iMac main firmware, since there is no simple way to enable writing to it).
+
+Further discussion and community support for this driver is available at:
+
+ - https://forums.macrumors.com/threads/pre-opencore-gop-support-for-efi-era-imacs-and-mac-pros.2378942/
+
+## Usage
+
+## Install to main firmware
+
+For reading and writing to main firmware on the Mac Pro, @Macschrauber's [Rom Dump](https://github.com/Macschrauber/Macschrauber-s-Rom-Dump) 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 main 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 [GPU firmware injection](#install-to-gpu-firmware). 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 GPU firmware
+
+Instructions and a script for inserting the driver into Nvidia or AMD GPU firmware (aka VBIOS) are provided.
+
+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.
+
+To use the provided `vBiosInsert.sh` script:
+
+ - Locate an appropriate version of the `nvflash` tool (Nvidia) or `amdvbflash` tool (AMD) (both are available for
+   Linux and Windows), which can be used to read from and write to the GPU firmware.
+ - Use that tool to read a copy of the GPU firmware.
+ - Run `./vBiosInsert.sh [-a|-n] {original}.rom EnableGop.efi {modified}.rom`, with `-a` for AMD and `-n` for Nvidia.
+    - If you have any problems with `vBiosInsert.sh` from a specific release
+    of EnableGop, please try the version included with the latest release of OpenCore
+    before reporting any issues.
+    The script receives updates to support additional graphics cards independently
+    of any bumps to the release version of EnableGop. If you need to, you can use
+    the latest version of `vBiosInsert.sh` to inject older versions of EnableGop.
+ - The new file `{modified}.rom` may be burnt to the GPU firmware.
+
+In the case of AMD, considerably less space is normally available, due to a strict limit of 128k for legacy and EFI 
+parts of the larger ROM image. If there is not enough space (i.e. script reports
+data would be truncated) then it is necessary to [strip some legacy VGA parts of the
+GPU firmware](https://github.com/Ausdauersportler/IMAC-EFI-BOOT-SCREEN/wiki/Deleting-the-VGA). This is beyond the scope
+of these instructions.
+
+If required to manually detect the GOP offset (this should normally be autodetected):
+
+> Using a hex editor, search in the GPU firmware dump 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 GOP offset value needed.
+
+For further information on GPU firmware 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

hackintosh-guide/Utilities/EnableGop/vBiosInsert.sh

@@ -0,0 +1,334 @@
+#!/bin/bash
+
+#
+# Copyright © 2023 Mike Beaton. All rights reserved.
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# Insert EFI into AMD or Nvidia VBIOS.
+# Tested back to Mac OS X 10.11 El Capitan.
+#
+
+usage() {
+  echo "Usage: ./${SELFNAME} [args] {rom-file} {efi-file} {out-file}"
+  echo "Args:"
+  echo "  -a              : AMD"
+  echo "  -n              : Nvidia"
+  echo "  -o {GOP offset} : GOP offset (auto-detected if Homebrew grep is installed)"
+  echo "                    Can specify 0x{hex} or {decimal}"
+  echo "  -t {temp dir}   : Specify temporary directory, and keep temp files"
+  echo "  -m {max size}   : Specify VBIOS max size (Nvidia only)"
+  echo "                    (For AMD first 128KB is modified, any remainder is kept)"
+  echo "Examples:"
+  echo "  ./${SELFNAME} -n -o 0xFC00 nv.rom EnableGop.efi nv_mod.rom"
+  echo "  ./${SELFNAME} -n nv.rom EnableGop.efi nv_mod.rom"
+  echo "  ./${SELFNAME} -a amd.rom EnableGop.efi amd_mod.rom"
+  echo ""
+}
+
+SELFNAME="$(/usr/bin/basename "${0}")"
+
+commands=(
+  "EfiRom"
+  "UEFIRomExtract"
+  "hexdump"
+  "grep"
+)
+
+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
+
+AMD=0
+AMD_SAFE_SIZE="0x20000"
+NVIDIA_SAFE_SIZE="0x40000"
+GOP_OFFSET="-"
+NVIDIA=0
+POS=0
+TRUNCATE=0
+
+while true; do
+  if [ "$1" = "-a" ] ; then
+    AMD=1
+    NVIDIA=0
+    shift
+  elif [ "$1" = "-n" ] ; then
+    AMD=0
+    NVIDIA=1
+    shift
+  elif [ "$1" = "-o" ] ; then
+    shift
+    if [ "$1" != "" ] && ! [ "${1:0:1}" = "-" ] ; then
+      GOP_OFFSET=$1
+      shift
+    else
+      echo "No GOP offset specified" && exit 1
+    fi
+  elif [ "$1" = "-s" ] ; then # semi-secret option to modify AMD safe size
+    shift
+    if [ "$1" != "" ] && ! [ "${1:0:1}" = "-" ] ; then
+      AMD_SAFE_SIZE=$1
+      shift
+    else
+      echo "No AMD safe size specified" && exit 1
+    fi
+  elif [ "$1" = "-m" ] ; then
+    shift
+    if [ "$1" != "" ] && ! [ "${1:0:1}" = "-" ] ; then
+      TRUNCATE=1
+      TRUNCATE_SIZE=$1
+      NVIDIA_SAFE_SIZE=$TRUNCATE_SIZE
+      shift
+    else
+      echo "No max size specified" && exit 1
+    fi
+  elif [ "$1" = "-t" ] ; then
+    shift
+    if [ "$1" != "" ] && ! [ "${1:0:1}" = "-" ] ; then
+      TEMP_DIR=$1
+      shift
+    else
+      echo "No temp dir specified" && exit 1
+    fi
+  elif [ "${1:0:1}" = "-" ] ; then
+    echo "Unknown option: ${1}" && exit 1
+  elif [ "$1" != "" ] ; then
+    case "$POS" in
+      0 )
+        ROM_FILE="$1"
+      ;;
+      1 )
+        EFI_FILE="$1"
+      ;;
+      2 )
+        OUT_FILE="$1"
+      ;;
+      * )
+        echo "Too many filenames specified" && exit 1
+      ;;
+    esac
+    POS=$(($POS+1))
+    shift
+  else
+    break
+  fi
+done
+
+if [ "$ROM_FILE" = "" ] ||
+   [ "$EFI_FILE" = "" ] ||
+   [ "$OUT_FILE" = "" ] ; then
+  usage
+  exit 0
+fi
+
+if [ "$AMD" -eq 0 ] && [ "$NVIDIA" -eq 0 ] ; then
+  echo "Must specify -a or -n" && exit 1
+fi
+
+if [ "$AMD" -eq 1 ] && [ "$TRUNCATE" -eq 1 ] ; then
+  echo "-m is not valid with -a" && exit 1
+fi
+
+if [ "$TEMP_DIR" != "" ] ; then
+  mkdir -p "$TEMP_DIR" || exit 1
+  tmpdir="$TEMP_DIR"
+else
+  # https://unix.stackexchange.com/a/84980/340732
+  tmpdir=$(mktemp -d 2>/dev/null || mktemp -d -t 'vbios') || exit 1
+fi
+
+ORIGINAL_SIZE=$(stat -f%z "$ROM_FILE") || exit 1
+
+if [ "$AMD" -eq 1 ] ; then
+  # For AMD we can only modify the first 128KB, anything above 128KB
+  # should not be moved, and is not mapped to memory visible by the CPU
+  # for loading EFI drivers.
+  TRUNCATE=1
+  TRUNCATE_SIZE="$AMD_SAFE_SIZE"
+
+  # Also works, with empty keep_part.rom, in the atypical case where we
+  # are provided with only the used part of the ROM below 128KB.
+  dd bs=1 if="$ROM_FILE" of="$tmpdir/modify_part.rom" count="$AMD_SAFE_SIZE" 2>/dev/null || exit 1
+  dd bs=1 if="$ROM_FILE" of="$tmpdir/keep_part.rom" skip="$AMD_SAFE_SIZE" 2>/dev/null || exit 1
+else
+  if [ "$TRUNCATE" -eq 0 ] ; then
+    # If original size is a plausible ROM size (exact power of two, 64KB or
+    # larger; 64KB chosen partly for neat regexp) treat it as the full available
+    # size of the VBIOS chip unless overridden with -m.
+    printf '%x' "$ORIGINAL_SIZE" | grep -Eq "^(1|2|4|8)0000+$" && TRUNCATE=1
+    if [ "$TRUNCATE" -eq 1 ] ; then
+      echo "Detected standard ROM size."
+      TRUNCATE_SIZE="$ORIGINAL_SIZE"
+    else
+      if [ "$ORIGINAL_SIZE" -gt "$((NVIDIA_SAFE_SIZE))" ] ; then
+        echo " - File size of ${ORIGINAL_SIZE} bytes must be no more than $((NVIDIA_SAFE_SIZE)) bytes; use -m or check file" && exit 1
+      fi
+      TRUNCATE=1
+      TRUNCATE_SIZE="$NVIDIA_SAFE_SIZE"
+    fi
+  fi
+
+  cp "$ROM_FILE" "$tmpdir/modify_part.rom" || exit 1
+fi
+
+if [ "$GOP_OFFSET" = "-" ] ; then
+  echo "Auto-detecting GOP offset..."
+
+  # nicer techniques which do not assume nice alignment of what is being searched for do not work on older Mac OS X
+  OUTPUT=$(hexdump -C "$tmpdir/modify_part.rom" | grep '55 aa .. .. f1 0e 00 00' | head -1)
+  # Make macOS bash to split as expected:
+  # shellcheck disable=SC2206
+  GOP_ARRAY=($OUTPUT)
+  GOP_OFFSET=${GOP_ARRAY[0]}
+  if [ "$GOP_OFFSET" != "" ] ; then
+    GOP_OFFSET="0x${GOP_OFFSET}"
+    GOP_OFFSET=$(($GOP_OFFSET))
+  else
+    GOP_OFFSET=-1
+  fi
+
+  if [ "$GOP_OFFSET" -eq -1 ] ; then
+    echo " - No GOP found in ROM!" && exit 1
+  fi
+fi
+
+dd bs=1 if="$tmpdir/modify_part.rom" of="$tmpdir/original_first_part.rom" count=$(($GOP_OFFSET)) 2>/dev/null || exit 1
+dd bs=1 if="$tmpdir/modify_part.rom" of="$tmpdir/original_last_part.rom" skip=$(($GOP_OFFSET)) 2>/dev/null || exit 1
+
+echo "Compressing EFI using EfiRom..."
+if [ "$AMD" -eq 1 ] ; then
+  EfiRom -o "$tmpdir/insert.rom" -ec "$EFI_FILE" -f 0xAAAA -i 0xBBBB -l 0x30000 -p || exit 1
+else
+  EfiRom -o "$tmpdir/insert.rom" -ec "$EFI_FILE" -f 0xAAAA -i 0xBBBB -l 0x30000 || exit 1
+fi
+
+if [ "$NVIDIA" -eq 1 ] ; then
+  dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_first_part" count=$((0x38)) 2>/dev/null || exit 1
+  dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_last_part" skip=$((0x38)) 2>/dev/null || exit 1
+
+  # TODO: truncation logic should be fixed for when there is not enough spare padding in output of EfiRom;
+  # we currently assume without checking that there is enough space to fit in the NPDE header (if not,
+  # script will report failure to verify with UEFIRomExtract below).
+  INSERT_SIZE=$(stat -f%z "$tmpdir/insert.rom") || exit 1
+
+  # Calculate NPDE size from original GOP and add to new image
+  EfiImageOffset=$(dd if="$tmpdir/original_last_part.rom" ibs=1 skip=$((0x16)) count=2 2>/dev/null | od -t u4 -An | xargs)
+  if [ "$EfiImageOffset" -eq $((0x50)) ] ; then
+    NpdeSize=$((0x18))
+  elif [ "$EfiImageOffset" -eq $((0x4C)) ] ; then
+    NpdeSize=$((0x14))
+  elif [ "$EfiImageOffset" -eq $((0x38)) ] ; then
+    NpdeSize=0
+  else
+    # Note: We need at least 0x14 NPDE size for the patch-ups we do below for size and end-marker to make sense
+    printf "Unsupported EFI Image Offset 0x%x, cannot calculate NPDE Size!\n" "$EfiImageOffset"
+    exit 1
+  fi
+fi
+
+if [ "$NVIDIA" -eq 1 ] && [ "$NpdeSize" -ne 0 ] ; then
+  echo "Adding Nvidia header..."
+
+  dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_first_part" skip=$((0x38)) seek=$((0x38)) count="$NpdeSize" 2>/dev/null || exit 1
+  cat "$tmpdir/insert_first_part" "$tmpdir/insert_last_part" > "$tmpdir/insert_oversize.rom" || exit 1
+  # Note: `truncate` command is not present by default on macOS
+  dd bs=1 if="$tmpdir/insert_oversize.rom" of="$tmpdir/insert_fixed.rom" count="$INSERT_SIZE" 2>/dev/null || exit 1
+
+  # Patch size in NPDE
+  dd bs=1 if="$tmpdir/insert.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x2)) seek=$((0x48)) count=1 conv=notrunc 2>/dev/null || exit 1
+else
+  cp "$tmpdir/insert.rom" "$tmpdir/insert_fixed.rom" || exit 1
+fi
+
+# patch with vendor and device id from original GOP
+dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x20)) seek=$((0x20)) count=4 conv=notrunc 2>/dev/null || exit 1
+
+if [ "$NVIDIA" -eq 1 ] && [ "$NpdeSize" -ne 0 ] ; then
+  # Patch EFI image offset in PCIR
+  dd bs=1 if="$tmpdir/original_last_part.rom" of="$tmpdir/insert_fixed.rom" skip=$((0x16)) seek=$((0x16)) count=1 conv=notrunc 2>/dev/null || exit 1
+
+  # Patch end marker in NPDE in fixed ROM (leave PCIR correct and EFI extractable from fixed ROM)
+  echo -n -e '\x00' | dd bs=1 of="$tmpdir/insert_fixed.rom" seek=$((0x4A)) conv=notrunc 2>/dev/null || exit 1
+fi
+
+echo "Combining..."
+cat "$tmpdir/original_first_part.rom" "$tmpdir/insert_fixed.rom" "$tmpdir/original_last_part.rom" > "$tmpdir/combined.rom" || exit 1
+
+# If new ROM is larger than truncate size, determine overflow by seeing
+# whether truncated ROM still has padding.
+# For Nvidia we would need to parse and navigate NVGI and NPDE headers
+# to calculate true occupied VBIOS space. To calcuate AMD occupation below
+# 128KB limit, we could navigate normal PCI expansion ROM headers.
+COMBINED_SIZE=$(stat -f%z "$tmpdir/combined.rom") || exit 1
+if [ "$COMBINED_SIZE" -le "$(($TRUNCATE_SIZE))" ] ; then
+  TRUNCATE=0
+fi
+if [ "$TRUNCATE" -eq 1 ] ; then
+  echo "Truncating to original size..."
+
+  dd bs=1 if="$tmpdir/combined.rom" of="$tmpdir/truncated.rom" count="$TRUNCATE_SIZE" 2>/dev/null || exit 1
+
+  COUNT=$(hexdump -v -e '1/8 " %016X\n"' "$tmpdir/truncated.rom" | tail -n 8 | grep "FFFFFFFFFFFFFFFF" | wc -l)
+  if [ "$COUNT" -ne 8 ] ; then
+    # Some Nvidia ROMs, at least, incorrectly have 00000000 padding after active contents
+    # (it is incorrect, since writing only active contents using nvflash resets the rest to ffffffff).
+    # May also be relevant if we ever have any truly 00000000 default ROM images.
+    COUNT=$(hexdump -v -e '1/8 " %016X\n"' "$tmpdir/truncated.rom" | tail -n 8 | grep "0000000000000000" | wc -l)
+  fi
+
+  if [ "$COUNT" -ne 8 ] ; then
+    echo " - Not enough space within $((TRUNCATE_SIZE / 1024))k limit - aborting!" && exit 1
+  fi
+
+  if [ "$AMD" -eq 1 ] ; then
+    cat "$tmpdir/truncated.rom" "$tmpdir/keep_part.rom" > "$OUT_FILE" || exit 1
+  else
+    cp "$tmpdir/truncated.rom" "$OUT_FILE" || exit 1
+  fi
+else
+  cp "$tmpdir/combined.rom" "$OUT_FILE" || exit 1
+fi
+
+# patch end marker in PCIR in out file
+echo -n -e '\x00' | dd bs=1 of="$OUT_FILE" seek=$(($GOP_OFFSET + 0x31)) conv=notrunc 2>/dev/null || exit 1
+
+printf "Verifying (starting at 0x%X)...\n" "$GOP_OFFSET"
+dd bs=1 if="$OUT_FILE" of="$tmpdir/out_efi_part.rom" skip=$(($GOP_OFFSET)) 2>/dev/null || exit 1
+# UEFIRomExtract error messages are on stdout, so we cannot suppress unwanted normal output here
+UEFIRomExtract "$tmpdir/out_efi_part.rom" "$tmpdir/extracted.efi" || exit 1
+ERROR=0
+diff "$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 " - ${OLD_EFI_COUNT} EFI parts in original ROM, and detected ${NEW_EFI_COUNT} EFI parts in modified ROM, expected $(($OLD_EFI_COUNT + 1))!"
+  ERROR=1
+fi
+
+if [ "$ERROR" -eq 0 ] ; then
+  echo "SUCCESS."
+else
+  echo "*** WARNING - FAIL ***"
+fi
+
+if [ "$TEMP_DIR" = "" ] ; then
+  rm -rf "$tmpdir" || exit 1
+fi
+
+echo "Done."