Path: utzoo!attcan!uunet!mcsun!hp4nl!star.cs.vu.nl!sreiz
From: sreiz@cs.vu.nl (=Steven Reiz)
Newsgroups: comp.os.minix
Subject: amiga minix bugfix
Keywords: amiga minix bugfix
Message-ID: <7958@star.cs.vu.nl>
Date: 16 Oct 90 15:05:52 GMT
Sender: news@cs.vu.nl
Lines: 47

Do you have an amiga with more than 512 KB chip ram?
Is minix acting weird?

If you answered YES! to both questions this posting is for you!

Recent amigas (A500s and A2000s with a 1MB agnus and A3000s) can have
(chip) memory in the $080000 - $100000 range and I just discovered that
minix has a bit of a problem with that... 

In fact on those machines it will add the screen memory and the disk buffers
to the free memory list. This means that if you execute a small minix program,
like ls, it will trash the disk buffers, and if you execute a large program,
or a program with a large data segment, like diskcopy, it will trash the
diskbuffers and the screen memory.

Indeed some people have reported exactly those problems: disk errors when
using various small programs and diskcopy messing up the screen.

Below follows a quick and dirty fix which will let minix think that your
machine does not have memory at $080000 - $0c0000:

Change your BOOT:s/startup-sequence, which should be:

BOOT:c/assign devs: BOOT:devs
BOOT:c/setmap m_usa1
BOOT:Minix -s 0 -e $200

to:

BOOT:c/assign devs: BOOT:devs
BOOT:c/setmap m_usa1
BOOT:Minix -s 0 -e $200 -n $080000

Note that I assume here that you have 'installed' the BOOT disk.
Please let me know if this fix works or not! (Preferably email to 
amiga@cs.vu.nl)
I will summarize to the net as soon as possible.
Unfortunately the code that causes the bug is part of the minix kernel, not
the loader, so a proper fix will require a new version of minix.img.
When I am sure how this bugfix works out I will recompile minix.img and
post it.

Please let us know of any other problems that you have with minix as well!

Regards,

                        Steven Reiz