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A script to help with diagnosing legacy BIOS boot issues on Macs
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| #!/bin/bash | |
| # | |
| # Get Partition Info from all disks | |
| # | |
| # Written by joevt updated Dec 29. 2020 | |
| # Patches marked "rgh" July, 2010, to dump information beyond the | |
| # four bios partitions | |
| # | |
| # sudo ./dumpvols.sh > dumpvols_result.txt 2>&1 | |
| # | |
| # Based on johnsock's AHCI Master Boot Record Patch. | |
| # | |
| # This script is freely distributable. | |
| # | |
| if [ ! "$USER" = "root" ]; then | |
| echo WARNING: This script must be run as root. | |
| exit | |
| fi | |
| MBRHASHES=\ | |
| "Windows_XP=d88d4f2dbc2c662db7d7d60ebf9e3e00 "\ | |
| "Windows_Vista=12c9d7ff4914c88a7f9eadf9211b861b "\ | |
| "Windows_7=118eb70c44cb69284e5d8aa93096831e "\ | |
| "None_all_zeros=4ebc676ce4896613a3a9df6e2a1c77ae "\ | |
| ""\ | |
| "MSDOS_or_FreeDOS_on_FreeDOS=93dd2ee87a995e36cbab0c2d5c2f041a "\ | |
| ""\ | |
| "Windows_XP_On_BootCamp2_with_AHCI_patch=c3fb54174bc479899d4ef6e45308dc18 "\ | |
| "Windows_XP_On_BootCamp2=cb4dabdd862da0508083b05814e198b8 "\ | |
| "Windows_Vista_on_XP_with_AHCI_patch=4979e1b9d70738759280f6962c2ad298 "\ | |
| "Windows_7_on_XP=7db43c1425e9ff3077dd62b776a50419 "\ | |
| "Windows_7_with_AHCI_patch=a243d3475531b0f6f0d7199043c2eb5c "\ | |
| "Windows_7_on_XP_with_AHCI_patch=24977c27865adec9ac8298f1a8d214bf "\ | |
| ""\ | |
| "Apple_Partition_Map_Block0_Driver_Descriptor_Map_390721968_blocks_and_Tiger_OS_9_drivers=087f35e49a39d52a46e3a94882869f51 "\ | |
| "" | |
| #All VBR hashes use all the bytes starting from offset 0x60. It may be better to use a different range for each type of VBR... | |
| # GRUB2 hash was incorrectly named GRUB #rgh | |
| # added GRUB hash from observation of kununtu 9.04 #rgh | |
| # added Windows 8 | |
| VBRHASHES=\ | |
| "None_all_zeros=acf496fff71230daa6985a701f83ce49 "\ | |
| "NTFS_No_Loader=3be27456483746abb85cd614381dac5e "\ | |
| "NTFS_Windows_XP_NTLDR=dd1728a59343b9fa9458d80657f68771 "\ | |
| "NTFS_Windows_Vista_BOOTMGR=d1c278b56eeea9536d0eb5898fe6a0b5 "\ | |
| "NTFS_Windows_8_BOOTMGR=771df8b803f96296854316d3d5918812 "\ | |
| "GRUB_from_Ubuntu=332469fa146db809f58d6392e2e0bdce "\ | |
| "GRUB2_from_Ubuntu=9c249066e1eb9c842d8acdfe6d23a2e3 "\ | |
| "FAT32_FRDOS4.1=98050815221ee147066f99f806c23203 "\ | |
| "FAT32_FRDOS4.1_or_MSWIN4.1_BOOTMGR=aec608de8ac709d91e6f3340b643ab4d "\ | |
| "FAT32_NTFS_NTLDR=d9c3d66e975d2b3b122353951a598b32 "\ | |
| "FAT12_BSD_4.4_BOOTMGR=4cc92970d5a3350bc72d2b975e28b915 "\ | |
| "FAT16_Non_system_disk=2a3d0f51ad246f115aa7d37891788857 "\ | |
| "FAT32_Non_system_disk_or_EFI=34f2d1f3c3ecce5c00cae8f0b82c922b "\ | |
| "HFS_boot_block_0=28f5bc1563fbaedeb8dabbd4ef9eb4c2 "\ | |
| "" | |
| FindHash () { | |
| # $1: name of hashed contents | |
| # $2: list of known hashes | |
| # $3: the hash to search for | |
| DIDFIND=0 | |
| for CURHASH in $2; do | |
| THEHASH=$(expr "$CURHASH" : '[^=]*=\(.*\)') | |
| THEOS=$(expr "$CURHASH" : '^\([^=]*\)=') | |
| if [ "$3" = "$THEHASH" ]; then | |
| DIDFIND=1 | |
| break | |
| fi | |
| done | |
| echo "" | |
| if [ $DIDFIND = 1 ]; then | |
| echo "$1: $THEOS" | |
| else | |
| echo "$1: Unrecognized (hash=$3)" | |
| fi | |
| } | |
| disklist="$(diskutil list)" | |
| echo "$disklist" | |
| echo | |
| diskutil apfs list | |
| DRIVELIST=$(sed -n -E "/^[ ]*0: [ ]{0,25}([A-Za-z_]+)[ ]*\*[0-9.]+ [TGMK]B[ ]+(disk[0-9]+)$/s//\1_\2/p;/^[ ]*0: [ ]{0,26} .* \*[0-9.]+ [TGMK]B[ ]+(disk[0-9]+)$/s//whole_\1/p" <<< "$disklist") | |
| for PARTDRIVE in $DRIVELIST; | |
| do | |
| DRIVE=$(expr "$PARTDRIVE" : '.*_\([^_]*\)') | |
| PTYPE=$(expr "$PARTDRIVE" : '\(.*\)_[^_]*') | |
| echo "===============================================================================" | |
| diskutiloutput="$(sed -nE '/\/dev\/'$DRIVE' /,/^$/ p' <<< "${disklist}")" | |
| echo "$diskutiloutput" | |
| echo "---------------------------------------------" | |
| diskinfo="$(diskutil info $DRIVE)" | |
| echo "$diskinfo" | |
| echo | |
| BLOCKSIZE=$(sed -nE '/^ *Device Block Size: +([0-9]+).*/s//\1/p' <<< "$diskinfo") | |
| if [[ -z $BLOCKSIZE ]]; then | |
| BLOCKSIZE=512 | |
| fi | |
| DEVLIST=$(echo "$diskutiloutput" | sed -n -E "/^.* (disk[0-9]+s[0-9]+)$/s//\1/p") | |
| for THEDEV in $DEVLIST; do | |
| echo "---------------------------------------------" | |
| diskutil info $THEDEV | |
| done | |
| if [ "$PTYPE" = "Apple_partition_scheme" ]; then | |
| pdisk -r -l "/dev/$DRIVE" | |
| pdisk -r -l -f "/dev/$DRIVE" | |
| # use the same bytes as MBR hash even though Block0 contents are totally different | |
| HASH=$(dd if="/dev/$DRIVE" bs=1 count=446 2> /dev/null | xxd -p -l 440 | md5) | |
| FindHash "Block0 contents" "$MBRHASHES" "$HASH" | |
| dd if="/dev/$DRIVE" bs=1 count=512 2> /dev/null | xxd -c 16 | |
| elif [ "$PTYPE" = "GUID_partition_scheme" -o "$PTYPE" = "FDisk_partition_scheme" ]; then | |
| gptoutput="$(gpt -r show $DRIVE 2>&1)" | |
| gptoutput2="$(gpt -r show -l $DRIVE 2>&1)" | |
| fdiskoutput="$(fdisk /dev/r$DRIVE)" | |
| echo "$gptoutput" | |
| echo "$gptoutput2" | |
| echo "$fdiskoutput" | |
| HASH=$(dd if="/dev/$DRIVE" bs=1 count=446 2> /dev/null | xxd -p -l 440 | md5) | |
| FindHash "MBR contents" "$MBRHASHES" "$HASH" | |
| dd if="/dev/$DRIVE" bs=1 count=512 2> /dev/null | xxd -c 16 | |
| if [ "$PTYPE" = "FDisk_partition_scheme" ]; then | |
| PARTLIST=$(echo "$fdiskoutput" | sed -n -E "/^[ \*]+([0-9])\: .*\[[ ]*([0-9]+) \-[ ]+([1-9][0-9]*)\].*$/s//\1_\2_\3/p") | |
| PARTTYPE="MBR" | |
| else | |
| HASH=$(dd if="/dev/$DRIVE" bs=1 skip=$((BLOCKSIZE + 96)) count=416 2> /dev/null | xxd -p -l 440 | md5) | |
| FindHash "GPT Header @ 1: GPT Header contents" "$VBRHASHES" "$HASH" | |
| dd if="/dev/$DRIVE" bs=1 skip=$BLOCKSIZE count=$BLOCKSIZE 2> /dev/null | xxd -c 16 | |
| PARTLIST=$(echo "$gptoutput" | sed -n -E "/^[ ]+([0-9]+)[ ]+([0-9]+)[ ]+([0-9]+)[ ]+GPT part \-.*$/s//\3_\1_\2/p") | |
| PARTTYPE="GPT" | |
| fi | |
| for THEPART in $PARTLIST; do | |
| PNUM=$(expr "$THEPART" : '\([0-9]*\)_') | |
| PSTART=$(expr "$THEPART" : '[0-9]*_\([0-9]*\)_[0-9]*') | |
| PLENGTH=$(expr "$THEPART" : '[0-9]*_[0-9]*_\([0-9]*\)') | |
| HASH=$(dd if="/dev/$DRIVE" bs=1 skip=$((PSTART * BLOCKSIZE + 96)) count=416 2> /dev/null | xxd -p -l 440 | md5) | |
| FindHash "$PARTTYPE $PNUM @ $PSTART: VBR contents" "$VBRHASHES" "$HASH" | |
| dd if="/dev/$DRIVE" bs=1 skip=$((PSTART * BLOCKSIZE)) count=$BLOCKSIZE 2> /dev/null | xxd -c 16 | |
| done | |
| elif [ "$PTYPE" = "whole" ]; then | |
| HASH=$(dd if="/dev/$DRIVE" bs=1 count=416 2> /dev/null | xxd -p -l 440 | md5) | |
| FindHash "0 @ 0: VBR contents" "$VBRHASHES" "$HASH" | |
| dd if="/dev/$DRIVE" bs=512 count=1 2> /dev/null | xxd -c 16 | |
| else | |
| echo "Unknown partition scheme" | |
| fi | |
| done | |
| echo "===============================================================================" | |
| ioreg -rw 0 -c IOMedia | sed -n -E "/^[ \|]*\+\-o (.*) <class IOMedia[^a-zA-Z]/,/^[ \|]+ }$/p" | sed -n -E "/^[ \|]*\+\-o (.*)/s//\1/p;/^[ \|]* \| (.*)/s//\1/p;" | |
| echo "===============================================================================" | |
| bless --verbose --getboot | |
| echo "===============================================================================" | |
| bless --verbose --info | |
| echo "===============================================================================" | |
| ioreg -rw 0 -n AppleEFINVRAM | sed -n -E "/^[ \|]+[ ]+(\".*)$/s//\1/p;" | |
| echo "===============================================================================" |
Updates
Aug 28, 2025:
- Fixes and improvements.
Mar 20, 2025:
- Add MFS partition support.
- Add support for whole disk partition (no partition map).
Mar 16, 2024:
- Fixes for Mac OS X 10.5 Leopard.
- Fixed an issue where embedded HFS+ info was not output when a block is unexpectedly not all zeros.
Jul 28, 2023:
- Bug fixes.
May 20, 2023:
- Added 64-bit VSDB volume id to Volume UUID conversion for HFS and HFS+ partitions.
Dec 2, 2022:
- Fixes for Mac OS X 10.4 Tiger.
- Added the following (related to Mac booting from Open Firmware or EFI):
- Apple Partition Map
- APM Patch Driver
- HFS/HFS+ Boot Blocks
- HFS Wrapper
- HFS Master Directory Block
- HFS+ Volume Header
chosen,aliasesoptions(was previously output only for Intel Macs)
- Pass a disk name (e.g.
disk0) or a disk slice (e.g.disk0s2) to reduce the output to a single drive or partition.
what is b3e20f39f29211d697a400306543ecac ?
what is b3e20f39f29211d697a400306543ecac ?
It is b3e20f39-f292-11d6-97a4-00306543ecac or HFS_UUID_NAMESPACE_ID - a 128-bit UUID which is prepended to the 64-bit VSDB volume id of a HFS partition. The 192-bit result is passed to MD5 to generate a 128-bit Mac OS X volume UUID.
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Notes
Run the command before and after making partition changes. Use a different file name each time. This way you can compare the files to see what changed and to make sure the changes are correct.
This script does not list boot files. Do that manually for each partition you think should be bootable. The boot code in a VBR (also know as PBR) should show what file it's looking to boot. For Windows 7 and later, it should be BOOTMGR. That file should exist in the root directory with a Boot folder containing a BCD folder containing a BCD file. The BCD file contains a menu of items to be bootable and boot options. Use EasyBCD.exe to edit the BCD of any partition. The files may be invisible in macOS - type Command-Shift-Period to show invisible files in the Finder.