Dual Boot Linux Mint 21.2 and macOS with OpenCore Legacy Patcher and OpenCore Bootpicker

[rikerjoe]

Hello, fellow Tinkerers! Although real life has intruded on my tinkering over the last few months, I’ve managed to squeeze in a small project or two. One of my background projects during this low key period has been testing OpenCore Legacy Patcher (OCLP) on a variety of unsupported MacBooks in my collection, specifically in multiboot arrangements with multiple installations of macOS and Linux. I thought I’d share a few tidbits I’ve acquired along the way through my tinkering and invite others to contribute as well.

Most recently I’ve been testing installations on a MacBook Pro Retina, 15-inch, Mid 2015 (MacBookPro11,5) with a 500-GB SSD. The below represents my outcomes with this MBP, and I intend on trying the same with some older Pros and Airs in my collection soon.

On my 2015 MBP, I am using a single APFS container with multiple versions of macOS, each installed in separate volumes within the single container. By the way, Mr. Macintosh just posted a YT video about multiboot and OCLP where he opted to install multiple macOS versions in separate APFS containers. I’ve been using the single APFS container approach for quite a while to make optimal use of shared free space among the volumes, and have seen no ill effects to date. However, if any of you APFS wizards out there know why separate containers versus a single container is the way to go, please comment below.

My preferred macOS philosophy is to keep an installation of the latest version supported natively as a failsafe, and install one or more later macOS versions via OCLP in separate volumes. Monterey is the latest version of macOS supported natively by the 2015 MBP, so I have it installed in a volume in the APFS container. I installed Ventura and Sonoma via OCLP in separate volumes in the same APFS container as Monterey. I configure OCLP to always show the OpenCore bootpicker, which shows all three installed versions of macOS at boot. Cool.

I wanted to add a Linux distro to the mix, because why not? My preferred distro is currently Linux Mint 21.2. I created a separate partition on the SSD and installed Linux Mint into it, which went smoothly.

My goal was to get Linux Mint to show in the OpenCore bootpicker along with the installed versions of macOS. Here is what I did. Please note that these steps require mounting the EFI partition and making edits to a config.plist file, which if done incorrectly can mess up booting for your Mac. Please don’t do these steps unless you are comfortable with Terminal and unix commands and poking around the EFI partition.

Boot into macOS, mount EFI, and make a backup copy of the config.plist file under /Volumes/EFI/EFI/OC.

1. In Terminal, diskutil list - to identify where EFI is located, typically disk0s1
2. In Terminal, sudo diskutil mount disk0s1 - to mount EFI to /Volumes/EFI
3. Open a Finder window from the EFI mounted on your Desktop (you do have Finder configured to show mounted drives, right?) and navigate to config.plist - it should be under EFI/OC, or in your Terminal window surf to /Volumes/EFI/EFI/OC
4. Make a backup copy of config.plist before trying any of the methods below, just in case

Instructions for setting up multiboot via Dual Booting with Linux are located here: https://dortania.github.io/OpenCore-Multiboot/oc/linux.html. Here are the methods I tested. If you are going to switch methods, use a fresh copy of the config.plist file for each method to avoid mixing edits.

For Method A: OpenLinuxBoot -
This method uses OpenLinuxBoot.efi driver, which was added to OpenCore 0.7.3. OCLP 0.3.1 was based on OpenCore 0.7.4, so this and any subsequent version of OCLP should install this driver by default. OCLP 1.2.1 (the version I used) definitely installed the driver. However, this method needs an additional driver corresponding to the filesystem used for the Linux install to make the Linux kernels visible to the OpenCore bootpicker; the following steps are for installing an ext4 driver and checking a few other settings in config.plist.

1. Download ext4_x64.efi from here: https://github.com/acidanthera/OcBinaryData/tree/master/Drivers; if you used a different filesystem for your Linux install, find the corresponding driver and substitute it in the steps below (I only tested the ext4 driver, so your mileage may vary)
2. Copy ext4_x64.efi to the Drivers directory under /Volumes/EFI/EFI/OC; verify that OpenLinuxBoot.efi already exists in the Drivers directory. (It should.)
3. Edit config.plist in your favorite editor (I used TextEdit in macOS; you can use Xcode in macOS, or nano or pico or vim or whatever editor in Terminal if you like)
4. Verify that OpenLinuxBoot.efi exists as an entry in the Drivers section (it did in mine) and add an entry in the Drivers section for ext4_x64.efi (I copied a nearby entry in the Drivers section and edited it); make sure ext4_x64.efi is listed before OpenLinuxBoot.efi, or you might get boot problems (ask me how I know)
5. Verify RequestBootVarRouting, LauncherOption, and HideAuxiliary are enabled (they were in mine by default)
6. Exit and reboot - in theory, Linux Mint 21.2 (or your particular distribution) should appear in the OCLP bootpicker along with the various flavors of macOS installed previously

If the idea of adding a driver to your EFI from an external source is not palatable, or you run into problems with your particular filesystem driver, there is another option you can try. This one worked for me as well. Use a fresh config.plist file, not one with the Option A changes. (You did make a backup copy, right?)

For Method B: Chainloading an EFI Bootloader, Method 1: Using BlessOverride
This method requires that you know something about your Linux distribution’s bootloader, at least enough to recognize what bootloader your distribution uses and where it lives. There are some hints below, but by no means is it a comprehensive list.

1. Edit config.plist in your favorite editor (I used TextEdit)
2. Find the BlessOverride entry under Misc - in my case it was set to \EFI\Microsoft\Boot\bootmgfw.efi, which I believe is the default configuration to dual boot Windows; I did not see this driver contained in the Drivers directory from installation of OCLP, so I figured I could alter this entry with no ill effects
3. Look for your Linux distribution’s bootloader under EFI, and change the BlessOverride entry to match your bootloader; some common ones are
   1. \EFI\arch\grubx64.efi
   2. \EFI\ubuntu\grubx64.efi (this is what Linux Mint 21.2 uses)
   3. \EFI\systemd\systemd\systemd-bootx64.efi
4. Exit and reboot - an EFI entry representing your Linux install should appear in the OpenCore bootpicker along with the various flavors of macOS installed previously

There are other methods listed in the Dual Booting with Linux source which I didn’t try. In the end, I chose Method A as my preferred method since it shows the actual Linux kernel by name instead of a generic EFI entry shown in Method B1.

Have any of you experimented with multiboot arrangements with different Linux distros or other OSes? What bootpickers and methods did you try, and what worked well or not well for you? I would love to see your experiences below!

 

[phunguss]

I haven't played with rEFInd in many years... but OCLP was great in getting everything from 10.6.8 through Sonoma loaded on an iMac12,1. I haven't dared to try Windows or Linux on the same drive, I always prefer a secondary drive for isolation.

 

[mtriplett1]

rikerjoe, Thanks for this post. You taught me how to solve a problem I had been working on for months in just a few minutes. I tried both of your solutions and both were easily done and worked just great! Last Christmas, I was a very new Linux user, and the first thing I wanted to do was have a Linux Mint partition on my MacBook Air 2017 running Sonoma through OCP. I tried on and off for several months with OCP pretty much preventing anything but a 1 or 2 time successful dual boot. Both took just minutes to try. Thanks again for this!!

 

[rikerjoe]

rikerjoe, Thanks for this post. You taught me how to solve a problem I had been working on for months in just a few minutes. I tried both of your solutions and both were easily done and worked just great! Last Christmas, I was a very new Linux user, and the first thing I wanted to do was have a Linux Mint partition on my MacBook Air 2017 running Sonoma through OCP. I tried on and off for several months with OCP pretty much preventing anything but a 1 or 2 time successful dual boot. Both took just minutes to try. Thanks again for this!!

You’re welcome, glad the solutions are working for you.

After a few months of testing with my 2015 MBP, I found Method A would lead to occasional boot problems that I think are associated with the drivers loaded with the boot picker. Method B just works, and it is what I’m currently using on it. I have a similar test underway on a 2013 MBA and so far so good with Method A.

keep me posted on how it goes for you. I may pass along my information to the developer of the OpenLinuxBoot driver in case it is a funny bug with the 2015 MBP and would like to know if other models have problems, too.

 

[mtriplett1]

I finally decided on option B. Like you I wanted to see my distro name in the menu. Thanks again, and I’ll keep you posted!

 

[ryandesign]

rikerjoe, thank you also from me. When I installed Linux Mint for the first time a few months ago, it set up the computer to boot into grub automatically. Later I rebooted to a macOS partition using the boot picker after which I could not figure out how to return to Linux until I found your very helpful instructions. Your "Method A" works well for me on a 2011 13" MBP and avoids the need to ever see grub so I have not tried "Method B".

I have had to come back to these instructions several times because something (probably an OpenCore Legacy Patcher update but maybe a macOS update) wipes out my changes and I have to make them again. I grew tired of performing the same steps manually over and over so I wrote a script to automate them; maybe it will also be useful to others:

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected.

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected. - add_oclp_ext4_driver.sh

gist.github.com

 

[rikerjoe]

rikerjoe, thank you also from me. When I installed Linux Mint for the first time a few months ago, it set up the computer to boot into grub automatically. Later I rebooted to a macOS partition using the boot picker after which I could not figure out how to return to Linux until I found your very helpful instructions. Your "Method A" works well for me on a 2011 13" MBP and avoids the need to ever see grub so I have not tried "Method B".

I have had to come back to these instructions several times because something (probably an OpenCore Legacy Patcher update but maybe a macOS update) wipes out my changes and I have to make them again. I grew tired of performing the same steps manually over and over so I wrote a script to automate them; maybe it will also be useful to others:

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected.

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected. - add_oclp_ext4_driver.sh

gist.github.com

Yes, OCLP updates remove the OC directory from the EFI and install a new one, meaning we have to reapply the mods to the config.plist file after every update, as you discovered. Thanks for the script!

 

[mtriplett1]

rikerjoe, thank you also from me. When I installed Linux Mint for the first time a few months ago, it set up the computer to boot into grub automatically. Later I rebooted to a macOS partition using the boot picker after which I could not figure out how to return to Linux until I found your very helpful instructions. Your "Method A" works well for me on a 2011 13" MBP and avoids the need to ever see grub so I have not tried "Method B".

I have had to come back to these instructions several times because something (probably an OpenCore Legacy Patcher update but maybe a macOS update) wipes out my changes and I have to make them again. I grew tired of performing the same steps manually over and over so I wrote a script to automate them; maybe it will also be useful to others:

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected.

Adds ext4 driver to OpenCore Legacy Patcher so that a Linux partition can be selected. - add_oclp_ext4_driver.sh

gist.github.com

That script is going into my files! Thanks to all!! Almost can't wait till the next update.

Ultimately I wish I could keep refind running, but OCLP prevents all of that. If I was running a current supported macbook, this would be no problem at all!

 

[ryandesign]

I know I can get a custom icon to appear on my Linux Mint partition in OCLP by creating the file /Volumes/EFI/EFI/ubuntu/.contentFlavour with the contents

Mint:Linux

but does anyone know where to get the actual Mint.icns and ExtMint.icns icons to put in /Volumes/EFI/EFI/OC/Resources/Image/Acidanthera/GoldenGate/ that match the style of the existing icons? Or how the existing icons were created—is there a template or script somewhere that I can use to create my own in a matching style?

 

[rikerjoe]

I know I can get a custom icon to appear on my Linux Mint partition in OCLP by creating the file /Volumes/EFI/EFI/ubuntu/.contentFlavour with the contents

Mint:Linux

but does anyone know where to get the actual Mint.icns and ExtMint.icns icons to put in /Volumes/EFI/EFI/OC/Resources/Image/Acidanthera/GoldenGate/ that match the style of the existing icons? Or how the existing icons were created—is there a template or script somewhere that I can use to create my own in a matching style?

I haven’t tried it myself but there is this post on apple.stackexchange that might offer some insights.

 

[phunguss]

Dortania guide

Try this info for converting a folder of icons to icns

and a source logo

Here is my quick try at creating it for you, convert and try to insert it.