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Some background information - was: Re: Recipe for installing Debian on powerpc (G4, 32-bit) Mac? [failed installation -- looking for advice]


On 12/19/21 19:54, Johannes Brakensiek wrote:
> Sorry, that's my bad. Did not know only certain images are supposed to
> work.

In order to avoid this confusion in the future, let me briefly explain the

Both debian-installer, i.e. the application installing Debian, and the installation
images are assembled from a large number of individual packages.

In order to support a new platform, one needs to add support for this platform to
a number of different packages, both in debian-installer and d-i packages as well
as a number of other packages.

For debian-installer to work with PowerMacs, quite a number of changes were necessary
due to the complicated boot mechanism that these machines use. The packages that needed
to be changed or created, are:

- grub-installer
- partman-hfs (new package)
- grub2
- debian-cd
- debian-installer
- hfsprogs

While the changes in debian-installer, grub2 and debian-cd have been implemented for a long
time, the changes to grub-installer, hfsprogs and the new package partman-hfs were long
incomplete and I often just used crude hacks to get the installation working. None of these
crude hacks were naturally ever committed to the source code meaning that only a certain number
of installation images that included these hacks were more or less working. I eventually started
working on making the necessary changes to grub-installer and hfsprogs in a proper way and adding
a new proper partman-hfs package.

First of all, hfsprogs was unmaintained in Debian for a long time and due the way the package
is maintained upstream by Apple - as part of a large source code dump - it was rather challenging
to get hfsprogs updated to a newer upstream version. The source cannot be built as is on Linux but
needs customization. Furthermore, Apple quietly removed support for legacy HFS which I had to restore
as well when updating the package.

Then I worked on grub-installer to get support added for GRUB installation on PowerMacs using hfsprogs
and partman-hfs. I took me around three days with lots of testing and trial and error until I got the
changes right that needed to be made for grub-installer. A quite long and nerve-wrecking process given
the fact that you need to re-install Debian several times a day on a machine with a 1 GHz CPU. After
I got it all ironed out, I committed the changes to grub-installer.

Then hfsprogs needed to be changed again to add a hfsprogs-udeb package so that mkhfs and mkhfsplus were
available inside debian-installer. The changes did not take long to implement, but the package was stuck
in the Debian FTP NEW queue for almost a year. So, again for this change to be used, I had to resort to
temporary hacks. This is further complicated by the fact that hfsprogs uses the APSL license which Debian
currently considers to be non-free meaning that hfsprogs had to be moved to the "non-free" section which
Debian Ports currently does not support.

Last but not least, the partman-hfs udeb package is currently not part of the official Debian distribution
as I have not continued with the work while the updated hfsprogs package was still in the NEW queue. I
wasn't sure whether hfsprogs would still be accepted after such a long time, so I decided to rather wait
with partman-hfs.

The current situation is now that partman-hfs needs to be worked on next and Debian Ports needs to get
support for the "contrib" and "non-free" distributions. The former is relatively easy and since I already
have a rough draft package, it won't take me too long to get a proper partman-hfs package ready.

However, getting support for "contrib" and "non-free" added to Debian Ports is not trivial and also outside
my influence. I have been told by the Debian Ports FTP admins that there has been done some work to get
this implemented, but I have unfortunately no time estimate when this will have been finally implemented.

Until that has happened, please stick to the images that are known to work or wait until I release new
images with the missing temporary hacks implemented and which I am declaring as "supposed to work" or
"known to work". FWIW, since I also create images for other architectures, I'm trying to create new
images regularly. But I cannot always take care of the manual changes required for Apple PowerMac
which is why even newer images might not work.


 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

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