MP 1,1-5,1 Sequoia and Mojave on Same 5,1 Mac Pro?

[riven2000]

I'm running Sequoia 15.7.3 on a 5,1 cMP with OCLP, and am trying to find out how to run Mojave on the same machine for older software. It's installed now but won't boot. I'm a little fuzzy on this, but I think it has to do with OCLP not playing well with Mojave. Any way I can get both to run in this situation?

 

[Bigwaff]

Yes. Install Mojave on separate disk. Hold down Option key on boot to get Apple boot picker. Select Mojave disk.

 

[reader50]

I have every macOS installed on my cMP that it's capable of running: Snow Leopard through Sequoia. Tahoe will be added once OCLP supports it. Snow Leopard through Sierra have separate HFS+ partitions. Mojave through Sequoia share the same APFS partition. High Sierra has its own HFS+ partition on the SATA drive, but is in the shared APFS partition on the nVME drive.

Note: Leopard used to be bootable. I lost that capability after upgrading to X5680 CPUs. The Leopard kernel doesn't know what to do with this CPU family.

macOS versions that will boot through OCLP: Snow Leopard, High Sierra through Sequoia (and presently Tahoe).
macOS versions that will direct-boot: Snow Leopard through Big Sur.

notes: Catalina had to be installed with the DosDude install tool. Big Sur needs to be installed and patched via OCLP. But after that's all done, it will direct-boot.

Your copy of Mojave should boot through OCLP. Have you tried direct-booting (option key during boot)? If it won't boot either way, then try a reinstall while booted via OC. Or do that anyway, to cure the problem. Or use the DosDude install tool for Mojave while booted either way.

 

[riven2000]

Thanks all!! One thing I just remembered though - I'm using a Radeon RX 580 that doesn't have its own boot screen. Will this affect Mojave vs the OCLP boot screen? Haven't dealt with this in a while.

 

[reader50]

It will prevent you from using the firmware boot picker. It will be fine with the OCLP boot picker.