Re: Why it's so difficult to fix PowerMac booting for good
Hello,
On May 30, 2023 12:42:39 PM EDT, Linux User #330250 <linuxuser330250@gmx.net> wrote:
> On 05/30 2023 17:13 Stan Johnson wrote:
> > On 5/30/23 7:16 AM, Ben Westover wrote:
> >> The GRUB Manual [1] says that the PPC port of GRUB only supports booting Linux at the moment. AFAIK booting macOS with GRUB on x86 machines works by just chainloading macOS' UEFI bootloader. I assume this is what yaboot does as well, telling Open Firmware to load OS X's blessed binary instead of the second stage of yaboot and Linux from there. All we need to do is find a way to support Open Firmware chainloading from within GRUB.
>
> AFAIR yaboot does its magic within the CHRP boot script. It would be
> relatively easy to add an option to load GRUB, I guess. The "chain"
> would then start by choosing Mac OS (Classic), Mac OS X, or GRUB, via
> the yaboot CHRP script. But then, GRUB would be only managing Linux.
That makes a lot more sense now. The "first stage" of yaboot where you select Linux, OS X, or CD Boot is actually a script run by Open Firmware, and that's how it can so easily chainload, since it's just a script selecting which binary for Open Firmware to load.
In that case, instead of trying to integrate chainloading functionality into GRUB itself, we could just set a similar script to run before GRUB that allows you to make that selection.
--
Ben Westover
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