Title sais it all. Warn that OldWorld PPC users will reboot in macOS as their bootloader isn't configured yet.
Now your machine is booted in MacOS, open the BootX control panel.
BootX can be configured to start Linux upon boot. If you do this, you will
first see your machine boot into MacOS then, during startup, BootX will
load and start Linux. See the
Warn about GRP only. Install