Re: Why it's so difficult to fix PowerMac booting for good
Hi Adrian,
On 5/10/23 3:36 AM, John Paul Adrian Glaubitz wrote:
> Hello!
>
> On Wed, 2023-05-10 at 11:25 +0200, Frank Scheiner wrote:
>> On 10.05.23 10:24, John Paul Adrian Glaubitz wrote:
>>> [...]
>>> If we could get Apple PowerMac machines to boot from a FAT filesystem, the licensing
>>> issue with hfsprogs would no longer be a headache. According to Apple's documentation,
>>> booting from a FAT boot partition should work [4] but I have never gotten around to
>>> testing that.
>>>
>>> So, if anyone has the time and enthusiasm to be able to get an Apple PowerMac to boot
>>> off a FAT partition, please give it a try and let me know. If it works, we can replace
>>> the current bootloader installation in grub-installer [2] and fix the issue for good.
>>
>> See [5] for an implementation from end of 2018 (worked for me on a 11,2
>> Power Mac G5 and a Mac mini G4). The discussion that followed might be
>> also of interest.
>>
>> [5]: https://lists.debian.org/debian-powerpc/2018/12/msg00054.html
>
> Does your approach include a blessing tool? I want to avoid messing around with the NVRAM
> as this approach is very fragile. A blessed bootloader, on the other hand, is automatically
> displayed in the boot menu and booted unless any alternatives are present. It's therefore
> much more robust.
>
> Adrian
>
With this disk layout,
root@ppc-g5:~# parted -l
Model: ATA WDC WDBNCE0010P (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: mac
Disk Flags:
Number Start End Size File system Name Flags
1 512B 32.8kB 32.3kB Apple
2 32.8kB 1081kB 1049kB hfs Apple_Bootstrap boot
3 1081kB 43.0GB 42.9GB hfs+ Leopard
4 43.0GB 85.9GB 42.9GB hfs+ Tiger
5 85.9GB 223GB 137GB hfs+ Users
6 223GB 241GB 17.2GB ext3 Debian_7
7 241GB 258GB 17.2GB ext3 Debian_sid
8 258GB 301GB 42.9GB ext3 Gentoo
9 301GB 303GB 2147MB linux-swap(v1) swap swap
10 303GB 657GB 354GB ext3 data
11 657GB 1000GB 344GB hfs+ Archive
I think Apple_Bootstrap has to be either an HFS or an Extended HFS
partition. I tried creating fat, vfat, and ext2 filesystems on
Apple_Bootstrap, with the same contents, and the system booted from the
first HFS partitiion. If some program "blesses" another partition, then
it appears the G5 will try to boot from that partition -- when that has
happened, I have had to boot using the Debian 7.8 installation CD in
rescue mode to run "ybin -v" from Debian 7.8 to re-bless the
Apple_Bootstrap partition, though there is likely an easier way to
"re-bless" it.
There is some Gentoo documentation that says a "/boot" partition can be
configured as an ext2 partition, and the system will boot from that
partition if it's "blessed", but I haven't tried that:
https://wiki.gentoo.org/wiki/GRUB_on_Open_Firmware_(PowerPC)
I still use yaboot (I haven't found any way to configure GRUB to
dual-boot Linux and Mac OS X). My yaboot.conf file specifies
"/boot/vmlinux" and "/boot/initrd.img" for each Linux distribution, then
I use symbolic links in the individual root filesystems to boot the
actual kernel and initrd that I want. In yaboot, I use "x" to boot
Leopard and "m" to boot Tiger (and of course "c" to boot a CD or DVD).
One advantage to using an Apple_Bootstrap partition, instead of an
Apple_HFS partition, is that the Apple_Bootstrap partition doesn't
normally ever have to be mounted, unless yaboot.conf needs to be
changed. In addition, even if the internal PRAM battery dies and power
is lost, the G5 will (I think) continue to boot using the
Apple_Bootstrap partition, even if it is not "blessed" (at least that's
what happens on a Lombard G3 PowerBook).
-Stan
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