DragonFly bugs List (threaded) for 2007-04
Re: lenovo R60 SMP/APIC_IO woes
Matthew Dillon wrote:
No, its probably a summary interrupt from the IOAPIC. Because the BIOSHi Matt,
is stupid, hardware chipsets are often able to route *ALL* of the masked
IOAPIC interrupts to a single PIC interrupt. It's usually IRQ 7 or
IRQ 15. Since the method to disable this routing is not usually
documented, we have no way of turning it off short of hoping that the
BIOS knows how to do it when we use the IOAPIC. Some IOAPICs
automatically route this special interrupt if their pins are masked.
Unfortunately, pin masking is a normal part of our interrupt handling
code (linux does something nutty to try to avoid pin masking).
The only real solution is for us to not use IRQ 7 at all and just
mask it out on the PIC.
Reading this makes me wonder, what does FreeBSD do about this issue?
They do not have APIC_IO option (as far as i know they have just option
SMP) and it seems to be relatively trouble free in regards to
IOAPIC/LAPIC: On DragonFly it seems to be an issue more often.