Making the installer in Linux #

While you don’t need a fresh install of macOS to use OpenCore, some users prefer having a fresh slate with their boot manager upgrades.

To start you’ll need the following:

• 4GB USB Stick
• macrecovery.py

Downloading macOS #

Now to start, first cd into macrecovery’s folder and run one of the following commands:

# Adjust below command to the correct folder
cd ~/Downloads/OpenCore-0/Utilities/macrecovery/

Next, run one of the following commands depending on the OS you’d like to boot:

# Lion (10.7):
python3 ./macrecovery.py -b Mac-2E6FAB96566FE58C -m 00000000000F25Y00 download
python3 ./macrecovery.py -b Mac-C3EC7CD22292981F -m 00000000000F0HM00 download

# Mountain Lion (10.8):
python3 ./macrecovery.py -b Mac-7DF2A3B5E5D671ED -m 00000000000F65100 download

# Mavericks (10.9):
python3 ./macrecovery.py -b Mac-F60DEB81FF30ACF6 -m 00000000000FNN100 download

# Yosemite (10.10):
python3 ./macrecovery.py -b Mac-E43C1C25D4880AD6 -m 00000000000GDVW00 download

# El Capitan (10.11):
python3 ./macrecovery.py -b Mac-FFE5EF870D7BA81A -m 00000000000GQRX00 download

# Sierra (10.12):
python3 ./macrecovery.py -b Mac-77F17D7DA9285301 -m 00000000000J0DX00 download

# High Sierra (10.13)
python3 ./macrecovery.py -b Mac-7BA5B2D9E42DDD94 -m 00000000000J80300 download
python3 ./macrecovery.py -b Mac-BE088AF8C5EB4FA2 -m 00000000000J80300 download

# Mojave (10.14)
python3 ./macrecovery.py -b Mac-7BA5B2DFE22DDD8C -m 00000000000KXPG00 download

# Catalina (10.15)
python3 ./macrecovery.py -b Mac-00BE6ED71E35EB86 -m 00000000000000000 download

# Big Sur (11)
python3 ./macrecovery.py -b Mac-42FD25EABCABB274 -m 00000000000000000 download

# Monterey (12)
python3 ./macrecovery.py -b Mac-FFE5EF870D7BA81A -m 00000000000000000 download

# Ventura (13)
python3 ./macrecovery.py -b Mac-4B682C642B45593E -m 00000000000000000 download

# Latest version
# ie. Sonoma (14)
python3 ./macrecovery.py -b Mac-937A206F2EE63C01 -m 00000000000000000 download

From here, run one of those commands in terminal and once finished you’ll get an output similar to this:

• Note: Depending on the OS, you’ll either get BaseSystem or RecoveryImage files. They both act in the same manner so when we reference BaseSystem the same info applies to RecoveryImage
• macOS 12 and above note: As recent macOS versions introduce changes to the USB stack, it is highly advisable that you map your USB ports (with USBToolBox) before installing macOS.
• CAUTION: With macOS 11.3 and newer, XhciPortLimit is broken resulting in boot loops.
  • If you’ve already mapped your USB ports and disabled XhciPortLimit, you can boot macOS 11.3+ without issues.

Making the installer #

This section will target making the necessary partitions in the USB device. You can use your favorite program be it gdisk fdisk parted gparted or gnome-disks. This guide will focus on gdisk as it’s nice and can change the partition type later on, as we need it so that macOS Recovery HD can boot. (the distro used here is Ubuntu 18.04, other versions or distros may work)

Credit to midi1996 for his work on the Internet Install Guide guide which this is based off of.

Method 1 #

In terminal:

1. run lsblk and determine your USB device block
   
2. run sudo gdisk /dev/<your USB block>
3. if you’re asked what partition table to use, select GPT.
   
4. send p to print your block’s partitions (and verify it’s the one needed)
   
5. send o to clear the partition table and make a new GPT one (if not empty)
   1. confirm with y
      
6. send n
   1. partition number: keep blank for default
   2. first sector: keep blank for default
   3. last sector: keep blank for whole disk
   4. Hex code or GUID: 0700 for Microsoft basic data partition type
7. send w
   • Confirm with y
     
   • In some cases a reboot is needed, but rarely, if you want to be sure, reboot your computer. You can also try re-plugging your USB key.
8. Close gdisk by sending q (normally it should quit on its own)
9. Use lsblk to determine your partition’s identifiers
10. run sudo mkfs.vfat -F 32 -n "OPENCORE" /dev/<your USB partition block> to format your USB to FAT32 and named OPENCORE
11. then cd to /OpenCore/Utilities/macrecovery/ and you should get to a .dmg and .chunklist files
12. mount your USB partition with udisksctl (udisksctl mount -b /dev/<your USB partition block>, no sudo required in most cases) or with mount (sudo mount /dev/<your USB partition block> /where/your/mount/stuff, sudo is required)
13. cd to your USB drive and mkdir com.apple.recovery.boot in the root of your FAT32 USB partition
14. now cp or rsync both BaseSystem.dmg and BaseSystem.chunklist into com.apple.recovery.boot folder.

Method 2 (in case 1 didn’t work) #

In terminal:

1. run lsblk and determine your USB device block
   
2. run sudo gdisk /dev/<your USB block>
3. if you’re asked what partition table to use, select GPT.
   
4. send p to print your block’s partitions (and verify it’s the one needed)
   
5. send o to clear the partition table and make a new GPT one (if not empty)
   1. confirm with y
      
6. send n
   1. partition number: keep blank for default
   2. first sector: keep blank for default
   3. last sector: +200M to create a 200MB partition that will be named later on OPENCORE
   4. Hex code or GUID: 0700 for Microsoft basic data partition type
      
7. send n
   1. partition number: keep blank for default
   2. first sector: keep blank for default
   3. last sector: keep black for default (or you can make it +3G if you want to partition further the rest of the USB)
   4. Hex code or GUID: af00 for Apple HFS/HFS+ partition type
      
8. send w
   • Confirm with y
     
   • In some cases a reboot is needed, but rarely, if you want to be sure, reboot your computer. You can also try re-plugging your USB key.
9. Close gdisk by sending q (normally it should quit on its own)
10. Use lsblk again to determine the 200MB drive and the other partition
    
11. run sudo mkfs.vfat -F 32 -n "OPENCORE" /dev/<your 200MB partition block> to format the 200MB partition to FAT32, named OPENCORE
12. then cd to /OpenCore/Utilities/macrecovery/ and you should get to a .dmg and .chunklist files
13. mount your USB partition with udisksctl (udisksctl mount -b /dev/<your 200MB partition block>, no sudo required in most cases) or with mount (sudo mount /dev/<your 200MB partition block> /where/your/mount/stuff, sudo is required)
14. cd to your USB drive and mkdir com.apple.recovery.boot in the root of your FAT32 USB partition
15. download dmg2img (available on most distros)
16. run dmg2img -l BaseSystem.dmg and determine which partition has disk image property
    
17. run sudo dmg2img -p <the partition number> BaseSystem.dmg /dev/<your 3GB+ partition block> to extract and write the recovery image to the partition disk
    • It will take some time. A LOT if you’re using a slow USB (took me about less than 5 minutes with a fast USB2.0 drive).
      

Now with all this done, head to Setting up the EFI to finish up your work #