Re: Changing bootstrap method for NewWorld Power Macs
Hi Mark,
On 1/2/19 16:27, Mark Cave-Ayland wrote:
On 31/12/2018 13:15, Frank Scheiner wrote:
Sorry to hear that, though I think you need to provide additional details at this time:
What do you mean with "Debian images"? Because if you speak of the installer ISOs, my
changes won't change anything with their ability to boot on NewWorld Power Macs or
QEMU (I think).
The part I'm worried about is that OpenBIOS searches the Apple Partition Map for an
"Apple_Bootstrap" partition on PPC Mac machines, probes the FS, and then tries to
boot dev:part:,\\:tbxi, dev:part:,\ppc\bootinfo.txt and dev:part:,%BOOT in that order.
Is that done via the "standard" `boot` command with OpenBIOS?
I believe that yaboot blesses itself on the HFS "Apple_Bootstrap" partition which
allows OpenBIOS to locate and run the bootloader. My understanding is that you would
like to change to MBR and FAT16 which would then fail in QEMU as OpenBIOS doesn't
have a functioning FAT driver - is that correct?
I think so, but you are talking about the installed OS now. Earlier it
sounded like you were talking about the installer ISOs and my changes
don't touch the boot method used for these.
And still, my remark below should hold true:
My changes also do not remove existing code related to HFS as bootstrap. I expect
that you will be able to still create all relevant partitioning and file systems
manually from within the Debian installer, if needed to make it work under QEMU.
Other point: why can't you directly load kernel and initramfs with QEMU?
That is one potential workaround, but for years everyone has booted their PPC VMs
under QEMU with "qemu-system-ppc -cdrom path/to/cdrom.iso" and for me that is an
extremely high barrier, particularly for novice users, to require them to extract a
kernel and initrd from an ISO first.
I don't see a reason for that, because again the boot method for the
ISOs isn't changed. Sure, in the end the installed OS (via a default
installation) is then not bootable via OpenBIOS anymore, but users could
workaround that by extracting kernel and initrd and load them directly
with QEMU.
****
BTW could the "grubfs" stuff ([1]) not be used to access FAT? I mean by
just using `boot` and `boot-device` set to e.g.
`<OF_PATH_TO_1ST_MBR_PART>:,\grub`? So that the OpenBIOS defaults don't
change, but users could also boot from FAT16 on MBR partitioned drives.
[1]: https://github.com/openbios/openbios/tree/master/fs/grubfs
Cheers,
Frank
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