Re: Bochs / plex86 (was Re: C++?)

From: Paul Hepworth <paul1+vsta_at_nospam.org>
Date: Mon Mar 01 2004 - 11:26:42 PST

> >This is my first time playing with Bochs... is the ICU config bit ignore
> >done in a config file, or do I need to recompile Bochs?
>
> The latter, unfortunately. But the error messages Bochs logs are pretty
> good, so it's easy to find the bit of code to change.

Well, under Bochs 2.1.1, I have a vfat16 volume with all of the vsta .tz's
unzipped (with long filenames preserved via linux vfat driver). I have a
floppy image with grub 0.93 (latest version I could find though references
to 0.94 exist).
grub comes up just fine (and I can chainload the freedos that's also on the
vfat16 volume).
When I boot vsta with the following commands:
root (hd0,0)
kernel /vsta/boot/vsta
module /vsta/boot/cons
module /vsta/boot/namer
module /vsta/boot/wd d0:readp
module /vsta/boot/dos -d //disk/wd:wd0_dos0 -n fs/root
module /vsta/boot/init
boot

I get the following from bochs.
01251466473p[PIC ] >>PANIC<< write to port 20h = 02

If I remember right, port 20h is the control port for the primary interrupt
controller. (I remeber doing out 20h, 20h to clear the source in an ISR.)
I guess that's what your ICU abbreviation must have been: interrupt control
unit or similar.
Referring to handy dandy book on PC architecture...
8259 programmable interrupt controller ICW1 bit1 is for "single": 1 =
single, 0 = cascade.
Naturally, all AT+ PCs have a second cascaded 8259 (equivalent). Does VSTa
use only the one? Or does it later sit ICW1 bit 1 back to 0 and initialize
the other interrupt controller?
Anyway, you said it was safe to just setup bochs to ignore this bit. I'll
try it out.
Once I get up and running, should I consider modifying the vsta startup not
to write port 20h = 02 so that others could run in an unmodified bochs? Or
is there an important reason for vsta to do what it does? (I could always
make the modified bochs binary available.)

Paul
Received on Mon, 1 Mar 2004 12:26:42 -0700

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