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

[Eric "ManxPower" Wieling]

Andrew Kohlsmith 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"?

Here's a list form an Intel Server Board, Dual CPU support (only 1 CPU 
installed):

           CPU0
   0:  120413974    IO-APIC-edge  timer
   1:       2434    IO-APIC-edge  keyboard
   2:          0          XT-PIC  cascade
   8:          1    IO-APIC-edge  rtc
  14:     642794    IO-APIC-edge  ide0
  15:         51    IO-APIC-edge  ide1
  18: 1204255212   IO-APIC-level  wctdm
  19: 1198491079   IO-APIC-level  t1xxp
  21:    3395482   IO-APIC-level  eth0
  22: 1198502476   IO-APIC-level  wcte11xp