Re: Why it's so difficult to fix PowerMac booting for good
On 05/29 2023 21:01 Stan Johnson wrote:
I don't know anything about Apple_Boot, but you are likely right that it
is also hidden from Mac OS 9 and Mac OS X. It appears Apple_Bootstrap is
used only by NewWorld PowerPC Macs. It's just an HFS-formatted partition
that is type Apple_Bootstrap instead of Apple_HFS, so while it can be
mounted manually by Mac OS X, it isn't accessible by default. And I
don't think it shows up in the boot selector menu (option key at boot).
Apple_Boot, Apple_Bootstrap, Apple_HFS, Apple_HFSX... doesn't matter for
the OS Picker to list it. Only the filesystem is important (HFS and HFS+
support blessing), and if there's a blessed CHRP boot script or not.
All you need to add is a CHRP boot script to make it appear on the OS
Picker screen.
That's actually easy: no matter what your boot file is, it's probably
blessed. So, find which file that is. As an example, this might be grub.bin.
So, now simply create a text file of any filename (it really doesn't
matter!) with the following content:
<CHRP-BOOT>
<COMPATIBLE>
MacRISC MacRISC3 MacRISC4
</COMPATIBLE>
<OS-NAME>
Debian GNU/Linux
</OS-NAME>
<BOOT-SCRIPT>
" screen" output
load-base release-load-area
boot &device;,grub.bin
</BOOT-SCRIPT>
</CHRP-BOOT>
Now, simply bless the CHRP boot script filename instead of the original
one (grub.bin in the example). The CHRP script loads whatever you
specify, so in the example the original grub.bin...
Next time you boot, hold the option key and you should now see "Debian
GNU/Linux" (or whatever you wrote in the <OS-NAME> field) as one option
(with no icon). The important part really is that the <COMPATIBLE> field
matches the actual hardware -- if it doesn't, it won't be shown by the
OS Picker.
Look at https://wiki.gentoo.org/wiki/GRUB_on_Open_Firmware_(PowerPC) for
an example with the GNU icon, and also how to bless the CHRP boot script.
The last time I installed Debian SID with GRUB on a PowerBook Pismo, the
Apple_Bootstrap partition was mounted as /boot/grub (it might have been
/boot, I don't remember now). But it was a persistent mount. Everything
worked, except Mac OS and Mac OS X volumes could not be boot from the
menu (booting Mac OS X also doesn't work on an Intel Core 2 Duo system).
Actually, I was able to boot Mac OS X from GRUB. But if I remember
correctly, I had to play with it a bit as it isn't intuitive...
os-prober might be helpful as a starting point.
Unfortunately, I don't have the programming skills to fix it. If anyone
has found or developed working grub.cfg entries that allow booting of
Mac OS X and Mac OS 9, please let me know, as I would prefer to use GRUB
if I can. Also, if anyone has GRUB working on a PowerBook Lombard,
please let me know (AFAIK, that's the only NewWorld PowerMac that
doesn't work at all with GRUB; its Firmware version may be too old for
something that GRUB is doing.)
The oldest hardware I own is a Clamshell, original 1999 edition without
firewire. I have getting Debian installed on it on my "hobby to-do
list", but haven't found the time yet.
Linux User #330250
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