Subject: 128Mbyte memory Pentium Pro problem
To: None <current-users@NetBSD.ORG>
From: Tim W. Janes <>
List: current-users
Date: 07/26/1996 11:49:00
I am having problems getting NetBSD to see the full 128Mbytes of
memory in a Dell Dimension Pentium Pro machine.

I have been trying various values for the EXTMEM_SIZE parameter in the
kernel config file with some success.

I can increase it up to 111*1024 Kbytes without any problem.
(setting EXTMEM_SIZE= 113664 boot message reports 117047296 bytes)

If I go up to 119*1024 Kbytes ( or any number above) the system will
not boot - it ends up in the debugger.
(setting EXTMEM_SIZE= 121856 boot message reports 125435904 bytes)

I have not determined the exact figure that breaks the system, but it
is between 111 and 119 Mbytes.

The debugger trace is as follows ( manually copied leaving out all the
hex numbers)

Changing root device to wd0a
panic: ptdi 24e023
db> trace
_Debugger (......) at _Debugger+0x4
_panic				0x3b
_pmap_enter			0x56
_vm_fault			0x83f
_vm_fault_wire			0x31
_vm_map_pageable		0x288
_kmem_alloc			0x108
_pmap_pinit			0x17
_vmspace_alloc			0x41
_vmspace_fork			0x31
_vm_fork			0x26
_fork1				0x39e
_sys_fork			0x10
_main				0x45a

In fact I have only borrowed this Dell machines to try out PentiumPro
+ NetBSD for a particualr application prior to purchasing a number of
machines (with 128Mbytes memory) of our own.

Is this problem common to all 128Mbyte Pentium Pro's - if not
which Motherboards are OK?

Or is this a known problem that can be fixed?  

Thanks for any help

Tim Janes                   | e-mail :
Defence Research Agency     |    tel : +44 1684 894100
Malvern  Worcs              |    fax : +44 1684 895103
Gt Britain                  |   #include <std/disclaim.h>