Bug#323182: debian-installer: boot.img for sarge doesn't, on PPC

[Sven Luther <sven.luther@wanadoo.fr>]

On Tue, Aug 16, 2005 at 06:36:39PM -0400, Rick Thomas wrote:
> 
> It's clear that, as a practical matter, Apple doesn't mind if people 
> distribute the "boot block which is coming directly from Apple and has 
> a couple tens of m68k assembly instructions nobody could be bothered to 
> reverse-engineer", because other Linux distributions provide it and 
> Apple has not sued them.  So it would seem that the only thing keeping 
> it out of the Debian/PPC distribution is the Debian Freeness 
> guidelines.  I respect the guidelines, and wouldn't want to go against 
> them, but it seems a shame that we can't find a practical solution to 
> this.
> 
> 
> Would it be possible to have an otherwise fully functioning boot floppy 
> image minus the "non-free" part?  Then someone, while disclaiming all 
> connection with Debian except as an interested observer, could put the 
> "non-free" part on a website somewhere with instructions for combining 
> the two into a functioning boot floppy?

I can build the miboot files and distribute them from p.d.o, they can just not
be part of the release.

> Rick
> 
> 
> PS: Sven makes it sound as if reverse engineering the boot block is a 
> trivial bit of work.  That's not entirely true.  It's  only trivial if 

Well, we alreadsy know it is some 100 or so m68k assembly lines, and those are
mostly trap calls to the apple rom.

So, what is needed is :

  someone to take the bootblock and extract the code part from the bootblock.
  The format of the bootblock is described on some apple page.

  someone who dissasembles those assembly lines.

  someone who then mapps the trap calls to apple rom calls.

  Once that is done, we need to write a specification of what is supposed to
  happen to make it work, not mentioning the real code or what rom calls are
  made.

Then once zwe have that, someone fully not incvolved with the above can do the
reimplementing part :

  take the specification and rewrite said code.

Also, we need a compiler that is able to generate apple m68k code and thus
able to compile miboot, altough i have a version of codewarrior 4 or whatever
it was CD, which is needed to build miboot.

Now, it has been rumored that a boot code containing only the (free) non-code
part would be able to boot. Nobody tried though.

> you happen to have the necessary coding and de-coding skills and the 
> necessary background in calling Apple's OF boot-rom routines.  People 
> with those skills are few and far between.   And acquiring them from 
> scratch for this project is definitely non-trivial.  That's why I 
> didn't volunteer.  I don't have the skills and I don't have the time to 
> acquire them.

The first step can be done easily enough, and upto obtaining the m8k assembly
lines. Then we can go look for help from the m68k community, which probably
even has someone knowledgeable in apple roms. There are probably also books
mentioning how to program said roms, at least there was for the amiga
computers back then.

> Maybe we should establish a bounty for someone to reverse-engineer the 
> Apple floppy boot block.  That might get somebody with the necessary 

(A stack of 10 oldworld machines ? :)

> skills to come out of the woodwork...  If ten of us put up US$100, 
> would that be enough?

Probably, not sure though.

There is also the approach of applefreeing aid code, but they probably lost
the source code for it, altough chances are good it was directly written in
assembly.

Someone at apple releaseing the boot sector code as BSD code with the assembly
source would be well enough.

Friendly,

Sven Luther