Re: Why it's so difficult to fix PowerMac booting for good
Okay, so this whole issue got me thinking...
I couldn't find a way to boot from FAT because it doesn't support
blessing a file. I also couldn't find a default boot file, e.g. some
bootinfo.txt or similar (boot.b, boot.bootinfo, boot.xcoff, ??) that
Open Firmware would default to and use in case of FAT (with no chance to
bless a file). Such filename would have to be hard-coded in OF.
It seems, the only real convenient way to go remains HFS or HFS+. Which
got me thinking...
We could make a /binary image/ of a pre-configured HFS partition with a
version of GRUB installed and configured to search for the real
configfile to use for booting on any supported filesystem (not only
ext2/3/4; only limited by available GRUB file system support modules).
This image could be dd'ed to a target "NewWorld Bootblock" partition,
and OF would find and load the blessed GRUB on it (as pre-configured in
the HFS image). This GRUB would then search for a pre-defined UUID
filesystem with the real grub.cfg on it.
The only thing that would have to be done during installation is to make
/boot the right pre-configured UUID, so grub from the HFS binary image
will load grub.cfg from it.
OF3+
--> HFS NewWorld Bootblock: blessed bootinfo-style GRUB, hardcoded UUID
--> finds grub.cfg on [ext2/3/4, xfs, btfs, etc. /boot] and loads it
--> boot selected OS
Installation steps:
1. create NewWorld Bootblock anywhere on fresh or existing HDD
2. copy binary image of pre-configured image HFS+GRUB
3. create /boot of supported fs, with UUID used in image from step 2
4. Linux only ever needs to manage grub.cfg on /boot
This would transfer the need to non-free HFS utilities to be used by the
package maintainer only, who has to create the NewWorld Bootblock HFS
image and bless the bootinfo/GRUB2 bootloader file. The target system
installing the prepared image then doesn't need to use any HFS tools...
If GRUB would support something else instead of a filesystem UUID, we
could also use a partition type or something similar in the
pre-configured binary image for the NewWorld Bootblock HFS image...
BTW, apparently this guide uses such a way also, not blessing anything
on ext2, as previously (wrongly) suggested in this discussion:
https://wiki.gentoo.org/wiki/GRUB_on_Open_Firmware_(PowerPC)
IMHO for the OS Picker to work intuitively, an icon via a blessed
bootinfo file is key... (to be included in the NewWorld Bootblock HFS
image by the maintainer...)
Any thoughts?
Greetings, Linux User #330250
Some useful links:
https://flylib.com/books/en/2.316.1.51/1/ -- The Hardware Boot Process
https://flylib.com/books/en/3.126.1.47/1/ -- BootX
https://lowendmac.com/2018/installing-linux-on-powerpc-macs/
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