lenovo R60 SMP/APIC_IO woes

Petr Janda elekktretterr at exemail.com.au
Mon Apr 23 00:05:54 PDT 2007

Matthew Dillon wrote:
    No, its probably a summary interrupt from the IOAPIC.  Because the BIOS
    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.
Hi Matt,
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.


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