plan9 vs aout

[Jens Staal <staal1978@gmail.com>]

Dear all,

First a bit of background:
I am currently attempting to update the old i386-plan9 target for binutils/gcc
in order to generate a modern cross compiler targeting plan9.

I have extracted the changes done to gcc 3.0 and binutils 2.11.2 from:
https://9p.io/sources/extra/gcc/

My binutils and gcc attempts can be found at:

https://github.com/staalmannen/gcc
branch plan9 : porting attempt to current gcc (10)
branch gcc-3.0-plan9 : original port added to the 3.0 branch

https://github.com/staalmannen/binutils-gdb
branch plan9: porting attempt to current binutils (2.34)
branch binutils-2_11-plan9 : original port added to the 2.11 branch

Definitely not just a copy-and-paste endeavour unfortunately. The old port
almost 20 years old and some style and structure changes have happened in that
time.

I have built a binutils variant but when I try to compile a "Hello.S" with
i386-lucent-plan9-as and execute it under i386 9front, I get an error about
incorrect file header, so something is wrong.

What I learned from looking at the old port and trying to adapt it to compile in
a modern binutils background is that a lot of it is basically copied from the
generic aout target (I have some uncommitted changes where I am updating the
obj-plan9 files to modern modified obj-aout files with the original changes
applied).

So to my question: what are the differences between the plan9 file format and
what binutils would see as generic aout? 


PS. If someone would be interested to help out, you are more than welcome ;) DS.