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Date:      Tue, 13 Feb 2001 10:14:13 -0500
From:      Mark Stosberg <mark@summersault.com>
To:        freebsd-questions@freebsd.org
Subject:   configuring irqs for a dial out modem
Message-ID:  <3A894E85.F2081BE2@summersault.com>
References:  <F5A360E18D6D7144AEEF3CCC71C0638C51F4@rmexchcorp01.corp.real-med.com> <3A880148.A9C72029@summersault.com>

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Hello!

  After using FreeBSD as a server for a long time, I'm setting up at a
FreeBSD box at home for a desktop machine. I'm having trouble getting
the modem recognized. At this point, I think it's an irq related
problem. I've got a generic (but new) 56K modem card in a PCI slot. 

When I try using ppp or minicom with /dev/cuaa0 the machine locks up and
when I try 
/dev/cuaa1 I get a " device not configured" error. I rebuilt both
devices with MAKEDEV, which made no difference. I got out the card and
examined it, there are no jumpers on it to configure. 

Here's some parts of "dmesg" that might be interesting:

sio0: configured irq 4 not in bitmap of probed irqs 0 
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 8250 
sio1: configured irq 3 not in bitmap of probed irqs 0

I cross referenced this information with the a report from the BIOS. It
reports that it finds a  "Simple COMM Controller" with an irq that
varies, though it was never 4, to match above. However, the irq it
reported would always match this other line in "dmesg":

pci0: <unknown card> (vendor=0x118183 dev=0x4000) at 10.0 irq 7

So at that point I was convinced that the "pci0" entry was in fact my
modem card, and it was just a matter of getting the irqs aligned. 

In the BIOS the irqs were set to auto configure themselves. I tried to
force the card to have an irq 4 in the BIOS to match sio0, but I
couldn't get it be irq 4, so I approached it from the other side. In the
kernel, I found that sio0 was hardcoded to irq 4, so I set it to "10",
which I could also set in the BIOS, and rebuilt the kernel. (I should
note that this the first time I rebuilt a kernel-- it was easy enough to
do, but I didn't realize how long the compile took!). 

Eventually I rebooted and the irqs lined up as I had hoped--- sio0 and
pci0 both reported using irq 10 now, and the BIOS reported this location
for my card. ( Yeah! Right? Nope. ). Unfortunately, the errors were the
still the same, and the failure patterns were the still the same. I
decided I needed a guru at this point. :)

My ideas at this point are that:

	A. I have a poor understanding of how irqs and devices work. 
	B. My card is somehow too pitiful and generic. 

I'm guessing it's "A". :) 

Any tips? Thanks!

  -mark

personal website             }      Summersault Website Development
http://mark.stosberg.com/    {      http://www.summersault.com/


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