[coreboot] IRQ 9 on s2895 and s2892

Myles Watson mylesgw at gmail.com
Mon Mar 16 19:59:22 CET 2009

On Sun, Mar 15, 2009 at 1:43 PM, Rudolf Marek <r.marek at assembler.cz> wrote:
>>> 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.

All of the other interrupts from 0x0-0xf are set as Edge triggered in
the mptable, so that seems likely.

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

Again I'm ignorant.  How do I dump those values?


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