Re: Afterburner and Linux

From: Petr Stehlik <>
Date: Tue, 9 Jun 1998 00:00:26 +0100

On Fri, 5 Jun 1998 14:51:47 -0700, Michael Schmitz wrote:

MS>The only problem the AB040 poses on top of that is not doing bus snooping
MS>(plus maybe other weirdness we didn't discover yet). But the ball is back in
MS>your court now - I hope I could prove that Linux works on the AB040 when you
MS>don't cache the RAM.

Linux worked on my AB040 since a friend from Australia compiled first
kernel with support for 040 only (back in 1996). Current versions
(2.0.33 and 2.1.99) run on my AB040 OK as well. I haven't played with
ST/FastRAM caching yet. So I'd say that a plain Linux kernel can run
fine on *some* AB040 at least.

As for the peculiarities of AB040 (compared to stock Falcon):

- SCSI is very sensitive (when VIDEL generates screen the SCSI timeouts
  and/or produces errors or hangs whole kernel). When it happens to work
  (for example with NOVA graphics) the performance is painful (90 kB/s
  compared to 950 kB/s under TOS (yes I know I must not compare it)).

- when kernel is in FastRAM, the interrupts from MFP timer are somehow
  missed or lost, which causes wrong timming, scary BogoMIPS values and
  IDE lock up during partition check. This situation is definitely
  dependent on clock patch/buffer mod installed. I remember that with a
  certain pre-Nemesis clock-patch I used to run 2.0 kernels in FastRAM
  without problems.

>From the lines above it sounds like AB040 is a completely brain-dead
hardware hack that has a plenty of design bugs and can't actually run.
Surprisingly, many people use it for several years under TOS/MiNT or
even MagiC, they use both overclockers and SCSI drivers and are quite
happy with it. I think Linux still could be patched somehow to be more
AB040 friendly (by respecting its hardware misdesign, probably).

MS>Please also try running the kernel in FastRAM, just for reference.

Since ATABOOT version 3.1 it's impossible to place kernel in FastRAM,
just because FastRAM is there only if PMMU is correctly programmed.
During Linux boot the PMMU is reprogrammed so FastRAM disappears... On
one hand it's a pity as kernel runs very slowly in ST-RAM (up to 10-20
times slower than in FastRAM). On the other hand, more people are able
to boot it as they have to run it in ST-RAM and so never see the FastRAM
related problems.

E-mail:                        PARCP developer
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Received on ma. juni 08 1998 - 23:58:00 CEST

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