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Q148501: Preventing PCI Resource Conflicts on Intel-Based Computers

Article: Q148501
Product(s): Microsoft Windows NT
Version(s): winnt:3.5,3.51,4.0
Operating System(s): 
Keyword(s): kbhw kbHardware
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0 
- Microsoft Windows NT Server versions 3.5, 3.51, 4.0 
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SYMPTOMS
========

On your Intel-based (x86-processor-based) computer running Windows NT, after you
add another PCI device, the system stops responding (hangs) or the PCI device
may fail to operate.

CAUSE
=====

The Windows NT Hardware Abstraction Layer (HAL) HAL assigned an I/O port address
or memory resource for the new PCI device that overlaps with an existing PCI
device therefore causing a PCI resource conflict on your system.

Under normal operation, the system BIOS is responsible for setting the PCI device
resource requirements. When Windows NT loads, the Windows NT HAL sometimes moves
the PCI device resources. PCI devices are dynamically configurable. However, the
Windows NT HAL sometimes assigns overlapping I/O port addresses or memory
resources for the PCI devices.

WORKAROUND
==========

To resolve this problem, upgrade to Windows NT 4.0 and follow the instructions
under Windows NT 4.0 Upgrade Information below. To work around this problem use
one of the workarounds below.

Windows NT 4.0 Upgrade Information
----------------------------------

Under Windows NT 4.0, an option has been added to the BOOT.INI file that the
x86-based HALs can recognize. Note that only those HALs shipped by Microsoft
will recognize this switch. When a HAL recognizes the /PCILOCK switch (option),
the HAL does not allow the operating system to change the PCI device resources
as long as the system BIOS settings appear to be correct and complete.

If the adding of a PCI adapter causes a hang during boot, remove the offending
PCI adapter card. Reboot the system and modify the BOOT.INI file by adding the
/PCILOCK option. Shut down the system, add the new adapter card, and reboot the
system.

The Windows NT 4.0 HALs that currently have this fix in are: HAL.DLL, HALMPS.DLL,
and HALAPIC.DLL.

Workarounds
-----------

To work around this problem, do one of the following:

- Insert the PCI adapter cards to a different PCI slot. This option does not
  apply to PCI devices built in to the main system board (motherboard).

  -or-

- Change the driver load order for the conflicting PCI adapters. This is not
  always possible when the types of drivers loaded have to be in a
  pre-determined order. Be very careful when modifying the registry as an
  incorrect setting may cause the system to become unstable or unbootable.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT versions 3.5 and
3.51. Microsoft has corrected this problem in Windows NT 4.0 and in the latest
Windows NT 3.51 U.S. Service Pack. For information on obtaining the Service
Pack, query on the following word in the Microsoft Knowledge Base (without the
spaces):

  S E R V P A C K


MORE INFORMATION
================

When you write device drivers for Windows NT, remember that the call to
HalAssignSlotResources is the API that moves the PCI resources. Some drivers use
IoReportResourceUsage, as a HalAssignSlotResources alternative, with the current
resource settings obtained from the configuration space of the PCI device. The
calls to HalGetBusData and HalGetBusDataByOffset can be used to read the PCI
device configuration space. This method should only be used as a last resort as
it contradicts the purpose of having a dynamically configurable bus.

Additional query words: prodnt

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Keywords          : kbhw kbHardware 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT350search kbWinNT400search kbWinNTW350 kbWinNTW350search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS350 kbWinNTS351search kbWinNTS350search
Version           : winnt:3.5,3.51,4.0

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