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Date: Fri, 23 Jan 1998 23:54:55 +1000 (EST)
Organization: Chaotic Software
From: chaos@ultra.net.au
To: lizard@freemail.gr
Subject: RE: bin/5549: Kernel Problem
Cc: freebsd-bugs@FreeBSD.ORG
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On 23-Jan-98 lizard@freemail.gr wrote:
> 
>>Number:         5549
>>Category:       bin
>>Synopsis:       Kernel Problem
>>Confidential:   no
>>Severity:       non-critical
>>Priority:       medium
>>Responsible:    freebsd-bugs
>>State:          open
>>Quarter:
>>Keywords:
>>Date-Required:
>>Class:          sw-bug
>>Submitter-Id:   current-users
>>Arrival-Date:   Thu Jan 22 18:50:01 PST 1998
>>Last-Modified:
>>Originator:     Filargyropulos Stavros
>>Organization:
>>Release:        2.2.5
>>Environment:
>>Description:
>> My CPU is Cyrix
> 
> The lines are:dosdev=80, biosdrive=0, unit=0, maj=0
> Booting 0: wd(0,a)/kernel @ 0x100000
> text=0x126000 data=0x12000 bss=0x16ae4
> symbols=[+0x51c+0x4+0x12bd0+0x4+018051]
> total=0x279c29 entry point = 0x100000
> 
> Copyright (c) ...
> .....
> ....
> FreeBSD 2.2.5-RELEASE #0: Tue Oct 21 14:33:00 GMT 1997
> jkh@time.cdrom.com:/usr/src/sys/compile/GENERIC
> Fatal trap 1: privileged instruction fault while in kernel mode
> instruction pointer    =  0x8:0xf01beb8a
> stack pointer           =  0x10:0xefbfff38
> frame pointer           =  0x10:0xefbfff50
> code segment          =  base 0x0 , limit 0xfffff , type 0x1b
>                                =  DPL 0 , pres 1 , def32 1 , gran 1
> processor eflags      =  resume , IOPL=0
> current process       = 0 ( )
> interrupt mask         = net tty bio
> panic: privileged instruction fault
> 
> ( AND THEN REBOOTS)


I also have this problem. I have also found a fix which I emailed to -hackers
about 2 months ago I'm still waiting for an offical patch. If you can get the
machine booted, go and edit/sys/i386/i386/identcpu.c and where

static int
identblue(void)
{
  trap_by_wrmsr = 0;
  /* 
   * Cyrix 486-class CPU does not support wrmsr instruction.
   * The wrmsr instruction causes invalid opcode fault, and exception


line 566 add return 0;

so it reads

static int
identblue(void)
{
  return 0;
  trap_by_wrmsr = 0;
  /* 
   * Cyrix 486-class CPU does not support wrmsr instruction.
   * The wrmsr instruction causes invalid opcode fault, and exception


The problem is that the identblue() probe sets off a condition in the Cyrix
chip that causes frebsd to panic. The CPU I have that's causing the problem is
a Cyrix 686 P166+ MMX M2 chip.

Hope this helps.