From: Ching-Hsiang Chen <chchen@stat.fsu.edu>
Subject: Re: Kernel Panic
Reply-To: chchen@stat.fsu.edu
Organization: The Internet
Date: Wed, 7 Oct 1992 09:57:15 GMT

I am posting this message for my new friend Olli who has same
kernel panic problem due to an odd number of RAMs on board (mine is
5 mb and his 6 ):
--------------------------------------------------------------
From opp@otsoni.tkk.tele.fi Wed Oct  7 04:37:42 1992
Subject: Re: Kernel Panic

In article <1992Oct6.055750.8976@athena.mit.edu> you write:
|>After I installed 4 256k SIMMs to make my system 5 mb RAM, I've been
|>having kernel panic problems...

I am having problems after adding 2 more megs to make 6 Megs of RAM.
Linux does not boot at all !!!

When it reaches the point where it normally displays the partition table
of my harddisk, it either halts with an error message (see below)
or reboots immediately without any messages

I've done every possible msdog-based memory tests to the whole memory and
no errors were found, I've swapped the memory banks so that the new
memory is in low address space (0 to 2 Megs) I've tried running
8 MHz clock speed or adding 1 wait state, result is always the same:
	4 MB of RAM, Linux works
	6 MB of RAM, Linux does not boot

Have You had any success after posting ? Have You heard anyone using 5 or
6 Megs succesfully ? Do we have anything in common which could cause
the problem ?

My setup: 386sx 16 MHz, 4-6 M ram, AMI BIOS, NEAT Chipset, 
"TURBO 386sx" - board ( you can insert 4 M SIPPs and 4 M DILs )
42 MB Maxtor HDU, Paradise SVGA w. 512 k, Linux 0.98

	Olli Per{

PS: The error message
...
sock_init: initializing family 1 (AF_UNIX)	# this line is OK
General Protection: 0000
EIP: 0008:0000D69B
EFLAGS 00010246
fs: 0017
base: C0000000, limit 000A000
Pid 0, process nr 0
83 c3 fc 81 fb 88 d3 03 00 77
task[0] (swapper) killed: unable to recover
Kernel panic: trying to free up swapper memory space
In swapper task - not syncing

PPS: I'll post my problem to the Net as soon as my Newsposter is repaired.

From opp@otsoni.tkk.tele.fi Wed Oct  7 05:22:59 1992


Please do, I _have_ a working News-connection but temporarily
I cannot post anything and my System Administrator is too busy
to repair it. Maybe tomorrow...

(got another message from You while writing this, so comments to that too)

|1) The RAM chips are too slow, e.g. 120ns (not true, mine are 80ns)
I added wait-states and reduced clock speed, did not help.

|2) Remove or reseat the SIMMs (I tried to reseat them, but didn't work)
I moved the memory banks around, did not help (new memory works perfectly
when it is used as a low part of 4 megs)

I Have ideas of two possible reasons:

1. Linux is broken, it thinks that if you have more than 4 Megs, You must have
  8 megs. Has anybody reported that He/She has Linux 0.98 working in 5 or 6 M ?

2. The address lines are broken; the same ramchip is active in two different
   addresses (I had such a problem once in another machine in 1986 I think.
   It was a difficult job to find that bug !!!)
   So when CPU tries to write to an address above 4 Megs, it is succesfull
   and data can be read from that same address. BUT !!! the same data is
   visible in some address below 4 megs and causes "some confusion" there.

   This could be tested by a program which:
	- fills the memory below 4 megs with 0ffh
	- fills the memory above 4 Megs with 0h
	- checks that nothing has changed below 4 megs
   I don't have tools to test this. pity

BUT: I have tested my RAM with CheckIt and no errors were found. I am not
sure if this "stuck address-line" error is checked in that program.

--
TELEKEHITYSKESKUS   Internet: olli.pera@tkk.tele.fi
Oulun T&K-yksikko   X.400:    c=fi; a=mailnet; p=telesse; s=pera; g=olli 
P.O. Box 487        Tel:      +358-81-3151861       Fax: +358-81-3151899
SF-90101 OULU       Telex:    1081305 sf; attn: Olli Pera

Newsgroups: comp.os.linux