[plug] Interrrupt conflict question

[Tomasz Grzegurzko]

On Tue, Apr 15, 2008 at 11:04 AM, Bret Busby <bret at busby.net> wrote:
>
>  Hello.
>
>  For a number of reasons, a system rebuild was done on my portable computer;
> an HP NX5000.
>
>  In the course of the rebuild, with the system being dual booting with MS
> Windows XP and Debian etch, the network card appears to be not working in
> Debian etch.
>
>
> > From memory, when the system was originally built, with Windows XP and
> >
>  Debian sarge, we found that an interrupt conflict involving the network
> card and (I think) the graphic card, was present.
>
>  That was found and resolved, by installing the then current version of
> Ubuntu Linux, then installing Debian Sarge on top of it, to replace it,
> using the interrupt values allocated by the Ubuntu version.
>
>  Now, we have the "live" versions, I think they are named, of various Linux
> distributions, like Knoppix, where we insert an optical disk, boot from the
> optical disk, into a particular Linux distribution, and, "away we go", able
> to use the "live" Linux distribution, as if it is installed.
>
>  My query, then, is this; with Debian etch already (more or less) installed
> on the computer, would it work, to use a "live" disk of the current version
> of Ubuntu, to obtain the table of interrupts allocated by Ubuntu, and to
> modify the Debian etch table of interrupts, to correspond with the Ubuntu
> table of interrupts (I am assuming that the "live" version of Ubuntu, would
> create in RAM, a virtual table of interrupts for all of the hardware
> devices, for use while that OS is running)? And, how do I find the table of
> interrupts, that would include the interrupt numbers of the cards like the
> network card and the graphics card; what is the path/filename, for both
> Ubuntu "live" and for Debian etch?
>
>  Thanks in anticipation.
>
>  --
>  Bret Busby
>  Armadale
>  West Australia
>  ..............

Hi,

I think you've got some of the concepts a little off, but you're
getting there. The table of interrupts is assigned by the BIOS at boot
time and then the OS is notified, the OS can in some cases modify this
or leave them as the BIOS set them (there is an option in the BIOS for
this, something like "Automatic IRQ allocation". The only differences
that you care about between the two Linux-based installations you
describe are Kernel versions; the table of IRQs is not stored in RAM
however, it gets allocated each time you power the thing on. Generally
later kernel series will handle automatic allocations better, and way
back in the day it was necessary to turn on BIOS allocation rather
than Linux-kernel based allocation as it didn't really handle it too
well, but with a NX5000 I'd say you should be okay to let the kernel
do it. I've had such a machine before and never seen the kinds of
problems you're describing however..

To answer your question then: no :)

But in any case you can look under /proc/interrupts to see what's been
allocated.

Regards,
Tomasz