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DFI K6XV3+/66 - BIOS mod/patch to disable ACPI IRQ (re: IRQ 2) ?

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First post, by sofakng

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Are there any BIOS mods or patches for the DFI K6XV3+/66 to release IRQ 2 from ACPI?

The BIOS has an option to disable ACPI but according to MQDIAG (from PCMIDI), IRQ 2 is still not available.

I've tried using ModBin to modify the BIOS but I don't even see the hidden option that I can enable. However, I think it's possible because keropi is using another super socket 7 motherboard with the VIA3 chip and his BIOS does have the option... ?

Reply 1 of 1, by kmeaw

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IRQ 2 is normally used to cascade two interrupt controllers used on the original IBM PC AT. So IRQ 2 cascades to IRQ 8-15 on a second chip.
When a second 8259 chip was introduced, the IRQ2 line on the slots has been rewired to IRQ9 to free up IRQ2 on the first chip for cascading purposes.

Do you mean IRQ9 which is usually connected to the system control interrupt that is emitted from the SCIOUT# pin of VT82C596B?
If it is the case, you can use the SCI interrupt assignment register available in the PCI configuration space of the power management device (1106:3050) at offset 42 at the 4 least significat bits - see page 60 of the VIA VT82C596B datasheet.
The relevant code in your BIOS which sets up the SCI interrupt is located in awardext.rom at offset 0x2A25 for version 12/31/1999-VP3-596B-DD-2A5LED4GC-B0

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