DragonFly bugs List (threaded) for 2007-04
Re: lenovo R60 SMP/APIC_IO woes
Matthew Dillon wrote:
> :Hmm. I though APIC_IO was needed for SMP to work... I've
> :never been 100% sure about how the two
> :are coupled though.
> Most SMP systems ought to work without APIC_IO. Basically there are
> two types of APICs. Each cpu has a LAPIC, and the motherboard chipset
> has one or more IOAPICs. SMP requires the per-cpu LAPIC to be present
> but doesn't require the IOAPICs.
Nice to know! Thanks Matt!
> When you compile a SMP kernel without APIC_IO it will compile in LAPIC
> support but not IOAPIC support, and depends on the legacy 8259 (called
> the 'PIC') to route interrupts, which is sometimes more compatible
> with the BIOS.
In the last few hours I've noted about 24 'stray interrupt 7' messages while
running SMP (no IOAPIC) .. I'm guessing that these are incorrectly routed
> There are lots of potential gotchas but usually a SMP box will work
> in one or the other modes (IOAPIC or legacy PIC). If all else fails
> you can turn on emergency interrupt polling in /boot/loader.conf or
> with a sysctl. With emergency interrupt polling turned on only the
> timer and IDE disk IRQs need to be properly routed, and they
> usually are.
> kern.emergency_intr_enable (default 0 = off)
> kern.emergency_intr_freq (default 10 = 10hz)
Do these need to be set by the bootloader, I suppose so, eh ?
Thanks for all the info, Matt! As always you're a great help!
. . any ideas about my other problem (previous message) wrt 1/2 speed kernel builds?