Possible workaround for 'BTX halted' error

andrew clarke mail at ozzmosis.com
Sun Nov 22 17:35:14 UTC 2009


I have an old 200 MHz Pentium Pro.  A slow machine by today's
standards but my intention was to put a minimal installation of
FreeBSD 7.2 on it (ultimately installing to a CF or SD memory card
using an IDE adapter), turning it into a very basic home office
firewall and not much else.

One of the problems I encountered (which I've also encountered on
other old PCs) was the dreaded "BTX halted" error when attempting to
boot from the FreeBSD install CD:

  AMIBIOS (C)1992 American Megatrends, Inc.
  (C) 1992 - 1998 Intel Corporation.
  BIOS Version 1.00.18.CS1
  Intel Corporation VS440FX Motherboard
  Serial Number: M04090465

  0131072 KB

  Press <F1> Key if you want to run SETUP

  Hard Disk  0 Installed QUANTUM FIREBALL EL2.5A

  CD Loader 1.2

  Building the boot loader arguments
  Looking up /BOOT/LOADER... Found
  Relocating the loader and the BTX
  Starting the BTX loader
  BTX loader 1.00  BTX version is 1.01
  int=00000000  err=00000000  efl=00010246  eip=0002c85b
  eax=00000000  ebx=00000000  ecs=00000000  edx=00000000
  esi=00000000  edi=00040320  ebp=00093ff8  esp=00093fc4
  cs=002b  ds=0033  es=0033    fs=0033  gs=0033  ss=0033
  cs:eip=f7 f1 85 db 89 c1 89 45-94 74 08 8b 55 18 89 32
         89 7a 04 89 4d 98 8b 45-94 8b 55 98 83 c4 6c 5b
  ss:esp=91 01 00 00 dc df 09 00-00 00 00 00 00 00 00 00
         00 00 00 00 20 00 20 00-60 01 20 00 0b 00 20 00
  BTX halted

At this point the machine freezes.  Ctrl+Alt+Del won't reset it.

I've seen the same bug crop up occasionally for more than a few years
now (since FreeBSD 5.x, I think).  Presumably there's no urgency to
fix it.

Until now the workaround I used was to boot from floppy diskettes (all
five of them) made from the images in the \floppies directory on the
install CD.  The FreeBSD installer would then operate normally and
install from the CD.  But this is frustrating as diskettes are
obviously terribly slow and often unreliable.

Today by accident I found a much simpler workaround.  There's a
freeware program called PLoP Boot Manager that can be used to boot
from CD.  I burnt plpbtinnoemul.iso (from plpbt-5.0.4.zip) to CD on
another PC then got the Pentium Pro to boot from it.  When I reached
the boot menu I took out the PLoP CD, replaced it with the FreeBSD 7.2
CD and told PLoP to boot from that.  FreeBSD 7.2 then proceeded to
boot from CD with no apparent problems.

I've successfully booted FreeBSD 7.2, 7.0, 6.2, 5.4 & 5.3 from CD on
this machine using the PLoP CD as a boot loader.  Also a recent
version of the FreeNAS LiveCD.  PLoP isn't required to boot the
FreeBSD 4.10 CD on this machine, but the 4.10 CD causes it to freeze
very early on with no messages displayed if I do use PLoP to boot it.


Apologies if this is long-winded, but I haven't seen this information
anywhere else, so I thought I'd pass it on!  I hope it helps someone.


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