abcs_of_irqs

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Date: Sun, 17 Dec 2000 03:26:04 -0800
From: Erik Steffl <steffl@bigfoot.com>
To: SVLUG <svlug@svlug.org>
Subject: [svlug] IRQ: how to find out which is to be used?

  I have internal modem (real one, it works, the question is not about
it and I know I should get external one:-) which acts as a serial port.
It is ISA PnP card, can use different IRQs.

  My main question is: how do I find out which IRQ it uses using linux
tools?

  the only way I can do it now is boot windows and peek into control
panel|system (btw it uses either 9 or 11)

  I have also a strange related story to contribute: I have this modem
along with other cards (ISA: sb awe 64, PCI: voodoo 3, network card
lne100tx) and it has been using IRQ 11 for ages. Since the network card
does not work properly, I taken all the cards out (except of
video&network) and tested the network card (just to see if there are any
strange confilcts, becuase previously I noticed that network card
conflicted with soundcard when inserted in particular PCI slot (even
though soundcardis ISA card)). No config files were changed, AFAIK.

  Later on I put all the cards back into computer (exactly the same
slots) and suddenly I noticed that modem works incredibly slow, it
couldn't connect (timeouts). I suspected IRQ so I rebooted win95 and
sure enough, IRQ for the modem was now 9 (it was 11 before). I rebooted
back to linux, changed IRQ to 9 and now the modem works.

  neither 9 nor 11 is used by anything else. however, network card used
to be 9 and now is 10.

  any ideas why was the irq changed?

  thanks in advance

	erik

===


Date: Sun, 17 Dec 2000 11:45:25 -0500
From: Brian Coyle <brianc@magicnet.net>
To: SVLUG <svlug@svlug.org>
Subject: Re: [svlug] IRQ: how to find out which is to be used?

Erik Steffl wrote:
> 
> It is ISA PnP card, can use different IRQs.
> 
>   My main question is: how do I find out which IRQ it uses 
> using linux tools?

$ man 8 pnpdump
$ man 5 isapnp.conf
$ man 8 isapnp


===

Date: Sun, 17 Dec 2000 11:00:41 -0800
From: Erik Steffl <steffl@bigfoot.com>
To: SVLUG <svlug@svlug.org>
Subject: Re: [svlug] IRQ: how to find out which is to be used?

Brian Coyle wrote:
> 
> Erik Steffl wrote:
> >
> > It is ISA PnP card, can use different IRQs.
> >
> >   My main question is: how do I find out which IRQ it uses
> > using linux tools?
> 
> $ man 8 pnpdump
> $ man 5 isapnp.conf
> $ man 8 isapnp

  pnpdump gives the possible configurations, not the one to use.

  it has the -c switch that attempts to find safe config but it uses
info about what is already used (/etc/interrupts and /etc/isapnp.gone),
which is not what I am asking about. In my case both irq 9 and irq 11
are free (not used) but only setserial /dev/ttyS2 irq 9 works. how do I
find that out? (without using win or trying all unused IRQs)

	erik


===


Date: Sun, 17 Dec 2000 11:47:57 -0800 (PST)
From: Rafael <raffi@linwin.com>
To: Erik Steffl <steffl@bigfoot.com>
Subject: Re: [svlug] IRQ: how to find out which is to be used?

On Sun, 17 Dec 2000, Erik Steffl wrote:

>   I have internal modem (real one, it works, the question is not about
> it and I know I should get external one:-) which acts as a serial port.
> It is ISA PnP card, can use different IRQs.
> 
>   My main question is: how do I find out which IRQ it uses using linux
> tools?

There are GUI tools in most decent distributions that can tell you about
hardware parameters just like the lame OS you mentioned elsewhere. Poke
around pulldown menus.

However, we have access to the kernel file system, assuming it's compiled
to do so, which is a huge advantage for troubleshooting, stats, and
monitoring.

 cat /proc/interrupts
           CPU0
  0:  271695712          XT-PIC  timer
  1:     629370          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  8:          6          XT-PIC  rtc
 10:    2542314          XT-PIC  eth0
 11:      54425          XT-PIC  53c7,8xx
 12:    6210633          XT-PIC  PS/2 Mouse
 13:          1          XT-PIC  fpu
 14:    6221167          XT-PIC  ide0
NMI:          0

As you can tell my PC doesn't show the sound card. But I do have one. I
can see it when playing 'saytime' for example. Why the difference?
Loadable modules.

cat /proc/interrupts
           CPU0
  0:  271751152          XT-PIC  timer
  1:     631862          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  5:     440957          XT-PIC  soundblaster
  8:          6          XT-PIC  rtc
 10:    2545965          XT-PIC  eth0
 11:      54425          XT-PIC  53c7,8xx
 12:    6212958          XT-PIC  PS/2 Mouse
 13:          1          XT-PIC  fpu
 14:    6221390          XT-PIC  ide0

So when you use /proc/interrupts you need to pay attention to how the
kernel works.

My  /etc/modules.conf

alias scsi_hostadapter ncr53c8xx
alias eth0 tulip
alias parport_lowlevel parport_pc
alias sound-slot-0 sb
options sound dmabuf=1
options opl3 io=0x388
#alias midi awe_wave
#post-install awe_wave /bin/sfxload /etc/midi/GU11-ROM.SF2
options sb io=0x220 irq=5 dma=0 dma16=0 mpu_io=0x330
alias char-major-81     videodev
alias char-major-81-0   bttv
pre-install bttv        modprobe -k msp3400; modprobe -k tuner
options bttv            radio=1
options tuner           type=5

>   the only way I can do it now is boot windows and peek into control
> panel|system (btw it uses either 9 or 11)

Whatz that?

It's a good idea to 'ls /usr/(s)bin' sometimes and then 'man whatever'
appears to be interesting. You "discover" all kinds of tools you never
imagined exist on your system.

For the brave souls, execute any of those programs as a regular user and
see what happens. Sometimes it tells you have to be root to run it and if
you read it's man pages you learn new command. Worth writing down 
the important ones and keep them in private quick admin guide.

>   I have also a strange related story to contribute: I have this modem
> along with other cards (ISA: sb awe 64, PCI: voodoo 3, network card
> lne100tx) and it has been using IRQ 11 for ages. Since the network card
> does not work properly, I taken all the cards out (except of
> video&network) and tested the network card (just to see if there are any
> strange confilcts, becuase previously I noticed that network card
> conflicted with soundcard when inserted in particular PCI slot (even
> though soundcardis ISA card)). No config files were changed, AFAIK.
> 
>   Later on I put all the cards back into computer (exactly the same
> slots) and suddenly I noticed that modem works incredibly slow, it
> couldn't connect (timeouts). I suspected IRQ so I rebooted win95 and
> sure enough, IRQ for the modem was now 9 (it was 11 before). I rebooted
> back to linux, changed IRQ to 9 and now the modem works.

Plug&play changes IRQ and DMA stuff on some cooperating (?) interfaces
during PeeCee selftest. Get a real computer based on Alpha, Sparc or such
CPU and you won't have this problems :-)

> 
>   neither 9 nor 11 is used by anything else. however, network card used
> to be 9 and now is 10.

/usr/sbin/sndconfig (RH) is a tool you can use to modify the parameters on
sound card. I usualy use IRQ5 for sound card since IRQ5 is by the
definition designated to the second parallel port (how good idea that
was?) which most computers don't use. Some older ethernet cards can only
use IRQ 5,7,9.

As we all know, PeeCee hardware (architecture sucks) so it's better to
have fixed IRQ and DMA parameters for bus handshaking than plug and play
with older cards.


===
From: Jean-Philippe.Laroche@cel.com
To: steffl@bigfoot.com, svlug@svlug.org
Subject: RE: [svlug] IRQ: how to find out which is to be used?
Date: Mon, 18 Dec 2000 14:40:18 -0800

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Often the best way is to turn off th eplug and play capability of the card, and configure the IRQ the old way, by asking for detection or assigning an IRQ.

I had no success with isapnp tools, so I used a dos program (from a floppy) to disable the PNP feature of the card.


===

From: dfox@belvedere.sbay.org
Subject: Re: [svlug] IRQ: how to find out which is to be used?
To: raffi@linwin.com (Rafael)
Date: Tue, 19 Dec 2000 18:39:38 -0800 (PST)
Cc: svlug@svlug.org

> As you can tell my PC doesn't show the sound card. But I do have one. I
> can see it when playing 'saytime' for example. Why the difference?
> Loadable modules.

Interesting. OTOH, my PCI netcard (no modules) doesn't show up in
/proc/interrupts unless it's activated via ifconfig eth0. I thought that
was kind of strange.

===

Date: Tue, 19 Dec 2000 19:35:24 -0800
To: dfox@belvedere.sbay.org,raffi@linwin.com (Rafael)
From: Ray Olszewski <ray@comarre.com>
Subject: Re: [svlug] IRQ: how to find out which is to be used?
Cc: svlug@svlug.org

At 06:39 PM 12/19/00 -0800, dfox@belvedere.sbay.org wrote:
>> As you can tell my PC doesn't show the sound card. But I do have one. I
>> can see it when playing 'saytime' for example. Why the difference?
>> Loadable modules.
>
>Interesting. OTOH, my PCI netcard (no modules) doesn't show up in
>/proc/interrupts unless it's activated via ifconfig eth0. I thought that
>was kind of strange.

In my experience (most of the relevant experience being with serial ports),
/proc/interrupts lists only the IRQs of devices that have been used. That's
why it's hard to spot the IRQ conflict caused by a NIC trying to use IRQ3
when an unused serial port (or modem) is also on that IRQ. 

Rafael, you might check if the sound card's IRQs show up *after* you play
something through it. David, I'd expect your NIC exierience to be the
standard way NICs get reported.

===

Date: Tue, 19 Dec 2000 22:29:40 -0800 (PST)
From: Rafael <raffi@linwin.com>
To: Ray Olszewski <ray@comarre.com>
Subject: Re: [svlug] IRQ: how to find out which is to be used?

On Tue, 19 Dec 2000, Ray Olszewski wrote:

> At 06:39 PM 12/19/00 -0800, dfox@belvedere.sbay.org wrote:
> >> As you can tell my PC doesn't show the sound card. But I do have one. I
> >> can see it when playing 'saytime' for example. Why the difference?
> >> Loadable modules.

[*] That's what I pointed out here. IRQ becomes "visible" when I run
'saytime' for example. Realaudio etc would do the same.

I thought I explained what's the difference in the above statement.

> >Interesting. OTOH, my PCI netcard (no modules) doesn't show up in
> >/proc/interrupts unless it's activated via ifconfig eth0. I thought that
> >was kind of strange.
> 
> In my experience (most of the relevant experience being with serial ports),
> /proc/interrupts lists only the IRQs of devices that have been used. That's
> why it's hard to spot the IRQ conflict caused by a NIC trying to use IRQ3
> when an unused serial port (or modem) is also on that IRQ. 
> 
> Rafael, you might check if the sound card's IRQs show up *after* you play
> something through it. David, I'd expect your NIC exierience to be the
> standard way NICs get reported.

[*]

===

Date: Wed, 20 Dec 2000 08:28:06 -0800
From: Erik Steffl <steffl@bigfoot.com>
To: svlug@svlug.org
Subject: Re: [svlug] IRQ: how to find out which is to be used?

dfox@belvedere.sbay.org wrote:
> 
> > As you can tell my PC doesn't show the sound card. But I do have one. I
> > can see it when playing 'saytime' for example. Why the difference?
> > Loadable modules.
> 
> Interesting. OTOH, my PCI netcard (no modules) doesn't show up in
> /proc/interrupts unless it's activated via ifconfig eth0. I thought that
> was kind of strange.

  that's what it says it docs, only 'occured' interrupts are shown in
/proc/interrupts, it does not report what you've set but what actually
happened.

===

Subject: Re: Installing Samba
From: Rick Moen <rick@linuxmafia.com>
Date: Thu, 21 Dec 2000 18:53:01 -0800

begin Todd Cary quotation:

> As many of you know, I have installed Red Hat Linux 6.1 on a computer
> that is on a NT network.  During the installation I was not asked about
> being on a network or about a NIC.

Are you the guy with the 3Com 3C509B ethernet card?  If so, did you 
remember to use the Etherdisk utilities to disable ISA Plug and Play, as
I mentioned?

If the installer didn't prompt you for network details, then it sounds
as if it didn't see your NIC.  It probably didn't see your NIC because
of the the &$%T#$+D#$# ISA PNP crud.

Ergo....

> What is my next step?

Disable the 3Com's PnP design-error.  Then start over.  (Yes, there are 
certainly ways to retroactively tell a distribution about a NIC that
it didn't find during installation.  I'm just not going to get into
those.)

If you'd rather not disable Plug'n'Pray, good luck to you.  The
advantage of my way is that it works.

===

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