re: IRQs in WinXP
Thursday, July 11, 2002 at 7:51 pm
Windows 98 Annoyances Discussion Forum
Posted by Everett
(2940 messages posted)
Johan: Glad to help out. WinXP handles IRQs differently, as you found out:
It is normal behavior for PCI devices to have IRQs shared among them, especially
on Advanced Configuration and Power Interface (ACPI) computers that have Windows
ACPI support enabled.
In Windows XP, Device Manager may list some or all of the devices on your ACPI motherboard
as using the same IRQ (IRQ 9). (To view the list of resources, click either Resources
by type or Resources by connection on the View menu). No option is available to change
the IRQ setting.
Windows takes advantage of the ACPI features of the motherboard, including advanced
PCI sharing. The PCI bus uses IRQ 9 for IRQ steering. This feature lets you add more
devices without generating IRQ conflicts.
Note that Windows XP cannot rebalance resources in the same way that Microsoft Windows
98 does. After PCI resources are set, they generally cannot be changed.
If you change to an invalid IRQ setting or I/O range for the bus that a device is
on, Windows XP cannot compensate by rebalancing the resource that was assigned to
that bus.
Windows XP does not have this ability because of the more complex hardware schemas
that Windows XP is designed to support.
Windows 98 does not have to support IOAPICs, multiple root PCI buses, multiple-processor
systems, and so on. When you are dealing with these hardware schemas, rebalancing
becomes risky and therefore is not implemented in Windows XP except for very specific
scenarios.
PCI devices are required to be able to share IRQs. In general, the ability to share
IRQs does not prevent any hardware from working.
The above is courtesy of article Q314068
On Thursday, July 11, 2002 at 12:11 am, Johan B wrote:
>Hello Everett,
>
>thanks for the tip! You were absolutely right: I manually assigned my ISA Soundblaster
>AWE 32 to IRQ 5, the same one W98 assigned to LPT1, and the system seems to work
>fine!
>
>One question though: how come LPT1 requires an IRQ in W98 and not in XP? Is the
latter
>more clever in handling resources?
>
>Thanks again, Johan
- Written in response to:
- Thanks, works for me! (Johan B: Thursday, July 11, 2002 at 12:11 am)
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