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Re: PowerPC bootdisks for potato release.

On Thu, Feb 10, 2000, Ethan Benson <erbenson@alaska.net> wrote:

>doesn't Miboot also require non-free Apple bootblock code in the 1K
>bootblock of the HFS partition?

Hum... the status of this bootblock code is difficult to determine. It's
only a few bytes of 68k assembly that calls the ROM _InitFS trap and
loads the remaining "boot " resources (and those contain only miboot
code). It would be difficult to write it differently. Also, any bootable
CD needs to have a this and the Apple CD driver in the partition map.
When burning a bootable CD with Toast on MacOS, Toast will actually
extract the CD driver from the MacOS driver and will put it in the
partition map.

If we _really_ want to make something absolutely and completely stripped
of any Apple code, miBoot should be turned into a fake CD driver burned
in the disk's partition map. This is possible but more complex and I
didn't have time to do yet. The current mecanism is really enough to make
bootable distribution CDs, and since all CD burning software always put
those boot stuffs on bootable CDs, I beleive there's no legal problems here.

>bootable CDs would rock, its not easy to accomplish however, in theory
>a small HFS partition with a CHRP script set to type tbxi and miboot
>as well should boot properly on all macs, but for oldworld macs you
>would need a non-free apple CD driver too.. and CD booting is
>reportedly a bit broken when you add ISO to the mix..

Yep. If you need bootable CDs, you need the CD to begin with an Apple
partition map (with a special layout for CDs) containing a CD driver and
at least one HFS partition with miBoot & yaboot on it. New versions of
the various redhat-based PPC distros will appear soon with bootable CDs,
so you'll be able to see how it's actually implemented.

For the "linux" part of the CD, you have several solutions: You can
simply have an ext2 image in a big file on the HFS partition and mount it
via loopback (slow). You can also probably add ext2 partitions using the
apple partition map of the CD, I _think_ the kernel will see them. You
can probably also do a multicession CD with the bootable HFS stuffs in
the first session, but tests must be done to see if MacOS can boot such CDs.

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