[coreboot] AMD platform: IO-APIC => Local APIC delivery modes

[Andriy Gapon]

On 10/10/2016 21:59, Rudolf Marek wrote:
> Hi Andriy,
> 
>> An example:
>> $ ioapic_wr 3 0xff00000000000300
> 
> I tried with minicom and IRQ 4, and I can confirm that NMI is delivered only
> when using the redirection entry above. The one 0x0000000000000400  does nothing
> in my case. I tested on AMD Hudson chipset,

It would be interesting to test 0x00...300 and 0xff...400 just for completeness.

> I had to add #include <stdint.h> to
> have the proper type defines under Linux.

I'll also add this one just in case.

> The NMI arrived to all CPUs, Linux said:
> 
> Oct 10 20:51:08 ruik kernel: [  891.596625] Uhhuh. NMI received for unknown
> reason 31 on CPU 2.
> Oct 10 20:51:08 ruik kernel: [  891.596631] Uhhuh. NMI received for unknown
> reason 31 on CPU 1.
> Oct 10 20:51:08 ruik kernel: [  891.596633] Uhhuh. NMI received for unknown
> reason 31 on CPU 0.
> Oct 10 20:51:08 ruik kernel: [  891.596636] Uhhuh. NMI received for unknown
> reason 31 on CPU 3.
> Oct 10 20:51:08 ruik kernel: [  891.596638] Do you have a strange power saving
> mode enabled?
> Oct 10 20:51:08 ruik kernel: [  891.596639] Do you have a strange power saving
> mode enabled?
> Oct 10 20:51:08 ruik kernel: [  891.596644] Do you have a strange power saving
> mode enabled?
> Oct 10 20:51:08 ruik kernel: [  891.596646] Dazed and confused, but trying to
> continue
> Oct 10 20:51:08 ruik kernel: [  891.596648] Dazed and confused, but trying to
> continue
> Oct 10 20:51:08 ruik kernel: [  891.596652] Dazed and confused, but trying to
> continue
> Oct 10 20:51:08 ruik kernel: [  891.596666] Do you have a strange power saving
> mode enabled?
> Oct 10 20:51:08 ruik kernel: [  891.596670] Dazed and confused, but trying to
> continue
> 
> I can try to contact Mr. AMD ask them to at least publish new errata versions.

That would be great.  I am really curious about the official clarification on
the issue.  Maybe there is a configuration bit that they forgot to set or
something like that.

I found a really old document about AMD-8131 chipset which seems like something
that later morphed into the APIC component of the southbrdiges and in that
document they discuss APIC -> HT mapping quite extensively.   I wonder what went
wrong later on.
In this copy of the document it's on page 67
http://www.tautec-electronics.de/Datenblaetter/Schaltkreise/AMD8131.pdf

-- 
Andriy Gapon