quirk_via_ioapic

Performs the following code when io_apic is enabled.

tmp = 0x1f;
pci_write_config_byte (dev, 0x58, tmp);

Which happens to be a bad idea(tm) on my Tyan Tiger 230T (Via 691+686 chipset) because it will cause one of the upper IRQ lines (>15) to trigger about 10M times / minute. In this case it's the ide controller, but is seen on other devices too.

Things sortof work w/o the quirk.
What is going on here ? :)

leeloo:~# cat /proc/interrupts...
 17:          0   IO-APIC-level  Ensoniq AudioPCI
 19:         12   IO-APIC-level  ide2
...

Pretending to use the quirk....

leeloo:~# pcitweak -w 0:7:0 -b 0x58 0x1f

And just a few seconds later...

leeloo:~# cat /proc/interrupts
...
 17:          0   IO-APIC-level  Ensoniq AudioPCI
 19:    2007685   IO-APIC-level  ide2