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

[Matt]

Eric,
I understand what you are saying about APIC... and from my understanding the
O/S takes over control of the IRQs.. but aren't there still only 15 physical
IRQs that you can set in the BIOS for devices?   I've never seen a machine
in which I could go above 15 for a device in the BIOS.

I have a machine on which I have APIC turned on and cat/proc/interrupts
shows:
          CPU0
  0:  103074143    IO-APIC-edge  timer
  1:         79    IO-APIC-edge  i8042
  2:          0          XT-PIC  cascade
  8:          1    IO-APIC-edge  rtc
 12:         93    IO-APIC-edge  i8042
 14:         23    IO-APIC-edge  ide0
121:     663241   IO-APIC-level  uhci_hcd:usb2, eth0
137:          0   IO-APIC-level  uhci_hcd:usb3
153:          0   IO-APIC-level  ehci_hcd:usb1
161:     104218   IO-APIC-level  ips
169:  103024435   IO-APIC-level  wctdm24xxp
NMI:          0
LOC:  103059761
ERR:          0
MIS:          0

Everything looks good, yes?  wctdm24xxp is on it's own IRQ.  However, that's
not entirely true.  If you do an lspci -vb you get:

[root at mrn-svr06 ~]# lspci -bv | grep -i "IRQ 11" --before-context=2
00:1d.0 USB Controller: Intel Corporation 82801EB/ER (ICH5/ICH5R) USB UHCI
Controller #1 (rev 02) (prog-if 00 [UHCI])
        Subsystem: IBM: Unknown device 02dd
        Flags: bus master, medium devsel, latency 0, IRQ 11
--
04:04.0 Ethernet controller: Unknown device d161:2400 (rev 11)
        Subsystem: Unknown device d161:2400
        Flags: bus master, medium devsel, latency 64, IRQ 11
--
05:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5721 Gigabit
Ethernet PCI Express (rev 11)
        Subsystem: IBM: Unknown device 02c6
        Flags: bus master, fast devsel, latency 0, IRQ 11

Ooops.  There's the Ethernet controller and the Digium (Unknown device) on
the same IRQ.


On 2/11/07, Eric ManxPower Wieling <eric at fnords.org> wrote:
>
> None of these mention APIC, so I assume they are written about machines
> without APIC support.  I'm sure what you claim was true in 1998, but is
> not true on any modern PC.
>
> Here are some links about APIC and IO-APIC.
>
> http://www.microsoft.com/whdc/system/sysperf/apic.mspx
> http://osdev.berlios.de/pic.html
> http://www.tek-tips.com/faqs.cfm?fid=4455
>
> http://www.asteriskguru.com/tutorials/pci_irq_apic_tdm_ticks_te410p_te405p_noise.html
>
> MANY other types of cards have issue with sharing IRQs.  This seems to
> be especially common with audio cards.
>
> Matt wrote:
> > Sure, not a problem.
> >
> > http://www.pcguide.com/ref/mbsys/res/irq/num.htm
> > *IRQ Number:* The number of the IRQ from 0 to 15.
> >
> > http://www.pcnineoneone.com/howto/irq1.html
> >
> > http://www.computerhope.com/irqs.htm
> > No, unfortunately with PCs they are limited to 00-15.
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