[asterisk-users] Re: Dell PowerEdge 2950 Sharing NIC IRQ with Digium Card

[Leo Ann Boon]

Matt wrote:
>
> I guess the question is... is it even possible to have a real-time 
> VoIP card running on PCIe?  Or with 1,000 Interrupts a second.. does 
> it simply need to have its own IRQ?
Have you tried the Sangoma PCIe cards?

APIC is supposed to fixed the PCI IRQ problem. AFAIK, APIC is not a 
virtual interrupt. It requires an additional interrupt controller to 
deal with the additional interrupt lines. The BIOS cannot see it because 
it's still stuck with the 8086 15-interrupt mindset. When you run a 
modern OS like Windows XP and Linux, the OS can will make the CPU aware 
of the additional interrupts from the secondary interrupt controllers. 
At the BIOS level, you'll see 'shared' interrupts for APIC system 
because the mobo designer need to cascade the new interrupt controller 
to the standard controller. Otherwise, the interrupts from the secondary 
controller will not be available to real-mode applications.

I believe the Digium cards (and some other cards as well) are picky 
about interrupts because of a faulty PCI controller. That said, the 
problem is usually more apparent in systems with PCI risers and entry 
level chipsets. In other words, you get what you pay for.

The other alternative is to use industrial PCs with a PCI backplane bus. 
So far, I've never encountered any interrupt issues with IPCs.

Leo