amd64 bsp issue on modern Kontron/Fujitsu board: spurious interrupt 7 on attempt to remap PIC.

[Karel Gardas]

On 12/30/20 12:17 AM, Joel Sherrill wrote:
> I didn't even know the x86_64 port was mature enough to run on real
> hardware. 
> 

It is, at least hello world and ticker seem to run fine! I'm hacking in
multiboot support but more and more tinker with an idea to play with
real uefi support. But for this I need to have reference point working
on my reference boards -- and unluckily those are those Kontron beauties...

> On the old PC PIC, irq 7 was the daisy chain from one 8259 to the other
> a d some hardware was prone to spurious interrupts. Google for "spurious
> irq 7". It may mean irq 13 (on the second 8259) has an interrupt at
> program start which should be cleared. But that's a guess

https://wiki.osdev.org/8259_PIC -- I've thought second PIC is hooked to
the IRQ2 line of the master...

Also since PIC is not remapped, then we probably can't decide if the
event happening here is CPU exception or real IRQ right?

Anyway, I've forgot to mention that linux/freebsd/openbsd run fine on
those boards so in the worst case I would need to debug/printf one of
these to find out required trick.

Thanks!
Karel