IRQ Confusion

[slacker_x]

I am suspicious that IRQ conflicts might be preventing my NIC from working in my new kernel.

This is really confusing. When I boot my comp, the bios spits out these values just before lilo:

IDE controller 14
Serial bus NA
Multimedia 10
Network controller 5
Display controller 11

where the number is the IRQ. There was other information too, but I thought this was the only important stuff.

what confuses me is that when I look at /proc/pci in my new kernel, both the ethernet controller and my USB controller are listed under IRQ 10.

What's going on???

I guess ideally I would like to be able to manually specify the IRQs, but in my award bios, it doesn't really make sense. If I choose to manually enable IRQs, all I have is a Y or N option for most IRQ numbers and dma.

eg. IRQ 5: Y
DMA 3: N


help!

[x]

In BIOS you normally specify whether IRQ's are assigned by PnP or legacy/ISA, You don't give each card an IRQ here. So your "Yes or No" - options probably answers a question like "Auto-assign IRQ's?" or something like that.

There is an option "Plug-and-Play aware OS" that shall be set to "No" when running Linux.
I believe this is more important than the IRQ-setting, but if you have problems set your IRQ's for manual/ISA/Legacy assignment.
Also make sure that your cards are not set to PnP.

Regarding 2 devices with same IRQ: this can work but it's not a good way to do it. Do you have USB-devices? If not it doesn't matter that USB & NIC share IRQ.

[slacker_x]

So if I do set them for manual assignment, does that mean entering a Y or an N?

and once they are set manual, how do I set the IRQ?

thanks
David Frey

[Lorithar]

turn off the pnp aware os flag...
remove all manually allocated irq/dma's

on the pci bus .. the cards will figure it out with the bus controller at startup.
check /proc/pci after boot .. this will list the pci card irqs and whatnot ..
What mobo/award bios level are you using.
I could check more for ya ...

[knute]

Originally posted by slacker_x:
So if I do set them for manual assignment, does that mean entering a Y or an N?

and once they are set manual, how do I set the IRQ?

thanks
David Frey


You have one of 3 options:
1) Jumpers/switches on the card itself
2) A dos based program on a floppy disk to configure the irq on an EProm Chip
3) It is hard coded into the hardware

Normally the third option is for ancient hardware before electronically programmable chips and the plethora of hardware available in todays market. :)

[slacker_x]

pnp aware OS flag is off
I moved the cards around in the case. now the soundcard is sharing with the USB controller.....haven't got that working yet either.

I am using award bios version 4.51PG

when I run ifconfig eth0 in my 2.2.18pre21 kernel, I get a line that says ip addr, bcast and mask, but in my 2.4.2 kernel I don't get that line.


another thing that is interesting is when I look at /proc/pci in my 2.2.18 kernel, there is no irq assigned to the USB controller, but in the 2.4.2 kernel there is

here are my ifupconfig eth0 messages from both kernels:

2.2.18pre21:
eth0 Link encap:Ethernet HWaddr 00:80:C8:F8:53:93
inet addr:24.69.108.236 Bcast:24.69.109.255 Mask:255.255.254.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:179 errors:0 dropped:0 overruns:0 frame:0
TX packets:176 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:58676 (57.3 Kb) TX bytes:13090 (12.7 Kb)
Interrupt:5 Base address:0xec00


2.4.2:
eth0 Link encap:Ethernet HWaddr 00:80:C8:F8:53:93
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:138 (138.0 b) TX bytes:0 (0.0 b)
Interrupt:10 Base address:0xec00

Thanks,
David Frey