Subject: Can UNIX coexist with AmigaDOS? Porting UNIX under AmigaDOS
To: None <amiga@NetBSD.ORG>
From: Frantisek Dufka <>
List: amiga
Date: 02/09/1996 16:44:50
Hello ladies and gentlemen,

I just had an idea. Running UNIX under AmigaDOS. I'd like to ask you -
developers and experienced users of NetBSD and AmigaDOS, if it could
be done in a relatively simple way.

Many people like idea of running AmigaDOS applications under Linux or NetBSD.
Couple of them thought about writing Amiga DOS emulator. Maybe somebody
started. But I'm sure nobody finished. Because it is almost impossible.
AmigaDOS is too much tied to hardware. To port this you have to rewrite
almost all the 0.5 MB ROM code to take care of UNIX environment. This could
take years of hard work!

But porting UNIX is far more simple, it is written to be portable. AmigaDOS
do not use MMU, so it is free for UNIX.

My idea is Linux or NetBSD running as one task (or few tasks) under AmigaDOS
like PC-Task or Shape Shifter.

All we have to do, to port Linux-m68k or NetBSD-Amiga is to rewrite kernel
core to not to take over hardware, i.e. not using interrupts and timers
directly, but using AmigaDOS instead (timer.device, interrupt handlers). MMU
and scheduling stuff can stay almost unchanged.

Then all lowlevel kernel drivers - console, scsi, ide, serial, .. etc. have
to be rewritten to use AmigaDOS devices. This will, by the way IMHO, reduce
kernel size.
All other things like networking, filesystems will stay unchanged.

AmigaDOS task switching and interrupt handling should be probably also
patched a bit, to restore back MMU tables to normal Amiga memory layout (but
protecting UNIX memory of course).

I'd like to ask you programmers and kernel hackers

How much of the NetBSD or Linux kernel sources should be really changed ?
Are there any problems which make it hard or impossible ?
What about system overhead ?
Is it worth of all the work ?

Any opinions ?

 Frantisek Dufka, age 21
 Computer Science student                     e-mail :
 Palacky University
 Czech Republic                 C64, A500, A1200 68030/28Mhz 8+2MB 1.2G HD

          Reality is for people who can't face science fiction