How to Disable PCI Bus IRQ Steering in Windows

ID: Q182628

The information in this article applies to:

Microsoft Windows 98

SUMMARY

This article describes how to disable Peripheral Component Interconnect (PCI) bus interrupt request (IRQ) steering in Windows.

MORE INFORMATION

When PCI bus IRQ steering is enabled, Windows dynamically assigns or "steers" PCI bus IRQs to PCI devices. If there are IRQ conflicts between PCI devices, you may need to disable PCI bus IRQ steering to determine where the conflicts occur. To disable PCI bus IRQ steering, follow these steps:

Click Start, point to Settings, click Control Panel, and then double-click System.

Click the Device Manager tab.

Double-click the System Devices branch.

Double-click PCI Bus, and then click the IRQ Steering tab.

Click the Use IRQ Steering check box to clear it, click OK, and then click OK again.

When you are prompted to restart your computer, click Yes.

NOTE: If you click No instead of Yes when you are prompted to restart your computer, the changes do not take affect.

NOTE: You may also have to disable PCI bus IRQ steering in your computer's basic input/output system (BIOS). For information about how to do so, contact you BIOS manufacturer.

The following settings determine which routing tables Windows uses when programming IRQ steering:

Get IRQ table using ACPI BIOS:

When this check box is selected, the ACPI BIOS IRQ routing table is the first table Windows tries to use to program IRQ steering. If a PCI device is not working properly, click this check box to clear it.

Get IRQ table using MS Specification table:

When this check box is selected, the MS Specification routing table is the second table Windows tries to use to program IRQ steering.

Get IRQ table from Protected Mode PCIBIOS 2.1 call:

When this check box is selected, the Protected Mode PCIBIOS 2.1 routing table is the third table Windows tries to use to program IRQ steering.

Get IRQ table from Real Mode PCIBIOS 2.1 call:

When this check box is selected, the Real Mode PCIBIOS 2.1 routing table is the fourth table Windows tries to use to program IRQ steering.

NOTE: By default, the "Get IRQ table from Protected Mode PCIBIOS 2.1 call" check box is not selected. You should only click this check box to place a check mark if a PCI device is not working properly.

IRQ Holder For PCI Steering may appear under IRQ Routing Status even though PCI bus IRQ steering is disabled. This can occur if the IRQ settings are being read by your computer's BIOS. For information about modifying the BIOS, contact your BIOS manufacturer.

For additional information about PCI bus IRQ steering, please see the following article in the Microsoft Knowledge Base:

Q182604 Description of PCI Bus IRQ Steering

Additional query words:


Keywords          : kbenv win98 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbhowto

Last Reviewed: January 30, 1999