We discovered a serious bug: booting High Sierra without System Integrity Protection (csrutil disable) possibly corrupts another mounted (unsupported) APFS2* OS Preboot volume, even when on another drive.
Consequently, the corrupted OS may appear as High Sierra and check for compatibility with Board IDs compatible with High Sierra, possibly prevents booting.
I've created a tool to address this problem.
This is a follow-up by the writings a while ago in a Macrumors thread:
https://forums.macrumors.com/threads/manually-configured-opencore-on-the-mac-pro.2207814/page-500?post=31995153#post-31995153
Screenshots of the issue:
Ventura with High Sierra icon and data volume name
Try to boot the newer OS with High Sierra's PlatformSupport.plist got prevented because Board ID of Mac Pro7,1 is missing, if not on the spoofless approach.
Booting High Sierra (natively) and having APFS2 Volume(s) in the machine could possibly replace SystemVersion.plist and PlatformSupport.plist in the Proboot volume of another mounted APFS2 OS with its own outdated version.
Also, the .contentDetails and .disk_label* files, which stores the name the BootPicker and OpenCore displays for the System name, could be renamed to the data volume name of the OS.
If the Data Disk name for this system is 'Ventura - Data', High Sierra could have set the name for the System to 'Ventura - Data.'
Where the latter is just cosmetic, the no more matching board ID in PlatformSupport.plist could make the system non-bootable.
Also we found that it replaces 3 .im4 files for Macs with T2 chip.
The following example details is for a Mac Pro 5,1: A wrong PlatformSupport.plist file of High Sierra gives a prohibited sign, or in verbose mode, the message for an unsupported board ID of a Mac Pro 7,1 Mac-27AD2F918AE68F61 if this machine is spoofed.
And shuts down hard after 30 seconds.
If we set the boot-arg -no_compat_check in OpenCore's config.plist, the OS ignores these issues and boots.
A wrong SystemVersion.plist file of High Sierra gives a High Sierra icon in the OpenCore boot menu (which is just cosmetic) but could prevent the OS from updating or installing an OS reading the wrong High Sierra version 10.13.x.
Replacing SystemVersion.plist, PlatformSupport.plist and the .im4 files with the proper versions.
They are also stored in the CoreServices folder of the System volume and in the i386 folder of the Preboot volume.
So we replace the Preboot files with the proper files, and the situation is fixed. If the OS cannot boot anymore because of the missing Board ID (prohibition sign or Board ID message), we need to either boot another APFS2 capable OS, mount the System volume, and replace the files or add the boot-arg:
-no_compat_check to the OpenCore config.plist.
Screenshots of the cure
1 Ventura SystemVersion_plist mismatch:
2 found High Sierra SystemVersion.plist in Ventura Preboot:
3 fix SystemVersion.plist?:
4 fixed SystemVersion.plist:
5 Ventura PlatformSupport_plist mismatch.png:
6 the report when the tool is done:
7 .contentDetails fix:
8 2nd readout, now ok:
9 Ventura icon and System name are back
10 ESPs were renamed by the Label all bootloader ESPstool of the Dumper package, names are correct (or adjusted).
Show and let rename the Preboot rendered name, as appears in the Apple Boot Picker or OpenCore boot menu.
Preboot fixer and renamer checks all Preboot folders for matching SystemVersion / PlatformSupport plists and .im4 files and asks for replacing them if they don't match.
If it is started on an APFS1 OS (late versions of Sierra, High Sierra, Mojave), it cannot mount the APFS2 System volume to read the original plists.
However, it alarms if it finds High Sierra SystemVersion.plist files in APFS2 Preboots.
The wrong .contentDetails and the .disk_label* icon drawn by the native Apple boot picker can be rebuilt by the tool as well.
You can edit the names and icons with the tool as well, even with multiple lines by entering option-return for a new line.
This is the button . Thanks to @joevt for all the help and providing the bash functions for it.
The names in the boot picker could be renamed by the preboot fixer and renamer tool.
The @joevt multiline names are ESPs, there is also a tool for renaming ESPs in the Dumper package
you can try to update the date of High Sierra's SystemVersion.plist
This needs more testing but it seems it helps, preventing High Sierra from replacing files in newer System's Preboots.
Boot High Sierra and do this in Terminal
sudo touch -t 203009110327 /System/Library/CoreServices/SystemVersion.plist
sudo touch -t 203009042358 /System/Library/CoreServices/PlatformSupport.plist
*
APFS1: APFS Systems with one volume
APFS2: APFS Systems with a separated system and data volume
I placed the tools in my firmware dumper package to ease administration.
They can be found in the Readme & other tools folder.
Using the Dumper to check and backup the bootrom is a good practice for all Macs, but that's another topic ;-)
link to the Macrumors Dumper post:
https://forums.macrumors.com/threads/high-sierra-booting-possibly-corrupts-newer-systems-fix-description-and-a-boot-picker-renamer.2415320/