[Asterisk-Users] Intel Desktop MotherBoards Unsuitable for Digium Boards

[Rusty Dekema]

How do you get your system to use IO-APIC style interrupts? I am running
linux-2.6.14 and have enabled "Local APIC support on uniprocessors" and
"IO-APIC support on uniprocessors" in the kernel options, but
/proc/interrupts says that everything is using XT-PIC. I am running an Intel
P3-1200 CPU although I forget what chipset the machine has. Is there an
option in the BIOS of a typical Intel machine that needs to be enabled in
order for this to work?

This has not been a problem in the past as I have been using only SIP and
IAX connections. But I have ordered a digium TDM card and will be installing
it tomorrow, and I would like to head off any potential problems if
possible.

-Rusty


On 11/9/05, Andrew Kohlsmith <akohlsmith-asterisk at benshaw.com> wrote:
>
> On Tuesday 08 November 2005 18:20, George Pajari wrote:
> > To make a long story short, according to Intel Dealer Technical Support
> > (we became Intel dealers in order to get answers to our questions) there
> > is no Intel motherboard that permits the IRQs to be configured uniquely.
> > They are all hardwired and shared. This information applies to both the
> > Intel Desktop Board and Server Board product lines.
>
> I find this almost impossible to believe.
>
> In XT-PIC mode, absolutely. However every modern chipset utilizes an
> IOAPIC
> now and every device has its own IRQ line. When the IOAPIC is in emulation
> (XT-PIC) mode, then yes many of the interrupts get "merged" into the
> standard
> 16 interrupts.
>
> However, if your Linux kernel is utilizing the IOAPIC's native mode things
> change drastically:
>
> # cat /proc/interrupts
> CPU0
> 0: 942314955 IO-APIC-edge timer
> 1: 10 IO-APIC-edge i8042
> 8: 1 IO-APIC-edge rtc
> 9: 0 IO-APIC-level acpi
> 12: 111 IO-APIC-edge i8042
> 14: 496236 IO-APIC-edge ide0
> 177: 211098355 IO-APIC-level eth0
> 185: 2 IO-APIC-level ehci_hcd:usb1
> 193: 0 IO-APIC-level ohci_hcd:usb2
> 201: 0 IO-APIC-level ohci_hcd:usb3
> 209: 86 IO-APIC-level ohci_hcd:usb4
> 217: 3769265646 IO-APIC-level wct4xxp
>
> As you can see on this particular system (not an Intel reference board,
> granted, but my Intel boards do work similarly) everything is on its own
> interrupt, and the interrupt numbers don't stop at 15.
>
> I'd really like some clarification on that... Do Intel reference boards
> actually tie the physical INT# signals of peripherals together, or are
> they
> just stating that unless you use the native IO-APIC mode you will have
> shared
> interrupts due to the "emulation"?
>
> Hopefully someone from Digium will step in and give the official word,
> because
> I have it on good authority that Digium hardware on Intel motherboards
> work
> well together. Hell, I've had my old P4 Intel reference board (with RamBus
> memory) work just fine without shared interrupts.
>
> -A.
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