OK, now it is certain, than quite any Linux distro can be installed to a GPT-partitioned drive in PowerMac
😀. First of all, you need to be sure that your OpenFirmware version can read GPT drives (I don't know all versions & their capabilities). Simplest way (may be) - partition something (HDD, USB flash or whatever) to GPT & create HFS partition. Later - try to use dir command in OF console & see the drive directory structure. (This all in brief to give all of us the idea what to do). As for now - reinstalled Debian to another IDE drive (Seagate 250Gb), GPT partitioned in Gentoo.
A bit of console output here
🙂.
root@PowerMacG5-QUAD:~# fdisk -l /dev/sdb
Disk /dev/sdb: 232,88 GiB, 250058268160 bytes, 488395055 sectors
Disk model: ST3250820A
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: ED67B67F-1F47-4B8F-9BDE-96BDFC2CA9CA
Device Start End Sectors Size Type
/dev/sdb1 2048 4196351 4194304 2G Apple HFS/HFS+
/dev/sdb2 4196352 488394751 484198400 230,9G Linux filesystem
root@PowerMacG5-QUAD:~# mount | grep /dev/sd
/dev/sdb2 on / type ext4 (rw,noatime,errors=remount-ro)
/dev/sdb1 on /boot/grub type hfs (rw,relatime,uid=0,gid=0)
root@PowerMacG5-QUAD:~# uname -a
Linux PowerMacG5-QUAD 5.14.0-1-powerpc64 #1 SMP Debian 5.14.6-3 (2021-09-28) ppc64 GNU/Linux
As you see, drive is GPT, 2 partitions. The idea to create a standalone partition for /boot/grub came from aforementioned video (but that guys don't finalize bootloader configuration & use pram reset, which is clumsy work). (BTW, I made this patition way too large - 2 GB, confused it to kernel storage place.) And (U)EFI-based systems uses EFI System Partition, whic is mounted to /boot/efi usually (well, this does not work for Intel Macs). Installation was quite simple. (Not to mention inability to select hfs partition at drive partitioning stage, so I left it unused). After packages install - do not use stage "install (yaboot|GRUB) bootloader", skip it directly to next pphase, BUT DO NOT REBOOT. Now we need to go to shell & chroot to our fresh installation; chroot /target/ /bin/bash. Mount our hfs partition to /boot/grub (mount /dev/sdXY, your drive letter & partition number here). Afterward - install grub2 (apt install grub2), it have to install grub-ieee1275 packages. Now install grub intself: grub-install (hfs partition). Check if our hfs partition is now populated (ls /boot/grub). Instead of creating grub image, I just copied quite everything from /usr/lib/grub/powerpc-ieee1275/ to /boot/grub/powerpc-ieee1275. You may try to reboot now (I made several reboots & amendmens before it all works & drive become shown in boot-picker). Several boot was made fro OF console (of paths is something to remeber
🙂 ). From actual system I've made ofboot directory in our hfs partition, placed very minimalistic ofboot.b config there.
(ofboot.b)
<CHRP-BOOT>
<COMPATIBLE>
MacRISC MacRISC3 MacRISC4
</COMPATIBLE>
<DESCRIPTION>
DEBIAN SID
</DESCRIPTION>
<BOOT-SCRIPT>
boot /ht/pci@9/ata-6@d/disk@1,:\grub
</BOOT-SCRIPT>
</CHRP-BOOT>
You can laugh but for about 2 or 3 attempts to boot from boot-picker I've just FORGOT to write command "boot" in this config
😀. (You see here is no OS-BADGE - If ever I can somehere find Debian logo or something else ...). Here Debian is bootable from boot picker, using GRUB2
🙂. This post does not pretend to be full detailed manual, just to give the idea what to do for GPT booting
🙂. This articles helps alot:
http://cynic.cc/blog/posts/running_grub2_on_powerpc_macs/
wiki.gentoo.org
(Congratulations are welcome
😀). (Interesting - is it possible to make such trcks with OpenSUSE..?
😀 )