Booting in EFI (and legacy CSM bios) mode not possible on older Apple EFI based systems (2)
Hi all
As mentioned in bug #71 (closed), there exist regarding the earlier Apple Intel computers a fundamental incompatibility in how the hybrid legacy/EFI CD images are build. Because of this, the standard legacy boot option is not accessible. And furthermore the EFI mode is also broken. This effectively prevents gparted to be used on those machines. In summary affected are the iMac4,1, iMac4,2, iMac5,1, iMac5,2 and iMac6,1 models. But this is also true for the corresponding Macbook, Mac-mini and MacPro models of that generation.
This problem is present also in 2021, it is not possible to start-up gparted in legacy or EFI mode. To make the legacy boot work, the gparted image has to be "remasterd" with a C program. That one removes all the EFI related information in the "CD boot sector".
However, I was finally able to find out the necessary GRUB / kernel parameters to get gparted working in EFI mode also on older 32 bit EFI based Apple iMac computers! The solution came from clonezilla, - to my really big surprise I was able to boot (in EFI mode) with their latest CD build 2.7.3-19 also on older Apple EFI computers.
After intensive testing I can confirm that also gparted is booting up (in EFI mode) at the affected Apple models when the following additional parameters are set: nomodeset
enforcing=0
xforcevesa
vga=791
Note, I have added them directly at the first (standard) boot entry. Maybe gparted uses a different standard resolution, so the vga=788
value would be also working.
So that's it! I recommend to add an additional Apple EFI specific boot entry like "Apple EFI mode" which contains the above mentioned parameters. ;-) And just to be clear, this would make sense not only for the 32bit x86 version but also for the 64bit x86-64 version of gparted. There exist also there a few models that cause problems, with these Apple specific EFI values also these should now boot up fine.