[coreboot] IRQ 9 on s2895 and s2892

Rudolf Marek r.marek at assembler.cz
Sun Mar 15 20:43:59 CET 2009

>> Maybe you can boot orig coreboot sources and see what device listens on IRQ
>> 9 ;)
> With coreboot without ACPI tables no one listens on IRQ 9.  With or
> without ACPI tables I get a spurious IRQ 7.

Hmm OK. Maybe there is some glitch on int line?

> These are interesting things from the boot log:
>  Nvidia board detected. Ignoring ACPI timer override.
>  If you got timer trouble try acpi_use_timer_override
>  Intel MultiProcessor Specification v1.4

Hmm this is because reference BIOS has some timer override bug. Its OK (the 
override when there is HPET)

>  ExtINT in hardware and MP table differ

This means that the pin for 8259IRQ is configured else where (the ExtINT) than 
it is written in MPTABLE. It may be some other bug?

This does not move us any further. It makes me wonder why the unchanged coreboot 
is not having the IRQ9 issue.

The only explanation could be that that usage the IRQ9 interrupt with ACPI is 
set to level, active low. But without ACPI it is unused and set to edge trigger. 
Maybe changing the 0x4d0 (ECLR) in unmodified coreboot from edge to level may 
expose again the irq9 problems.

Can you dump here the 0x4d0 and 0x4d1 so we can check how the level/trigger is set.


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