[vox-tech] [OT] IRQ's under win2k

Peter Jay Salzman vox-tech@lists.lugod.org
Sat, 13 Dec 2003 14:15:48 -0800


hi all,

i have a linux/win2k dual boot.  everything is fine under linux, but
i've got IRQ problems under windows.

the sound sucks under win2k, but only when playing games.  it's fine
when playing mp3's.  looking at the control panel, i noticed that the
whole damned system is assigned to IRQ 11:

    linux           win2k

1   timer           timer
2   keyboard
3   cascade
4   scsi            com1
5
6                   floppy
7
8   rtc             rtc
9                   ACPI
10
11  sound/usb/net   sound/usb/net/scsi/tv capture/AGP
12  PS2             PS/2
13                  mathco
14  ide0            ide0
15  ide1            id1
 

the problem is obvious -- sound cards generally don't like sharing IRQ's
to begin with, but having sound and video on the same IRQ is enough to
kill sound on games.  if i can get either sound or video off of 11, i'm
sure everything will be fine.

but here's the rub.  linux works perfectly.  i'm reluctant to start
pulling PCI cards out and redistributing them, because i don't want to
trade a problem under windows for a problem under linux.  besides,
everything is on 11, so i don't see how shuffling cards would work in
this case.

any ideas on what i should do?  i'm sufficiently unfamiliar with windows
that i'm not sure what resources are available to help resolve the
problem.

i can't find anything saying "assign IRQ X to PCI slot Y" in BIOS.
maybe i just don't know where to look.

however, there's options to "let BIOS assign IRQ X" and "reserve IRQ X".
i'm not sure what "reserve" means, but i'm assuming that "reserve" means
"don't assign IRQ X because an ISA card is going to want it".

the machine in question uses a networked printer and has no serial
devices, so IRQ's 3, 4, 5, and 7 are useless.  however, i can't find a
way to tell windows to use them.

help?

pete

ps- this kind of problem wouldn't happen under an AMD64 system, right?

pps- this just emphasizes the fact that i really have no idea how IRQ's
are assigned to begin with.  i know that certain PCI ports are tied to
share certain IRQ's, hence "shuffling PCI cards" is a way of dealing
with IRQ conflicts.  and i know that you can instruct BIOS not to assign
IRQ's to let ISA cards take them.  but there must be more to that.  why
would all my PCI cards be assigned to the same IRQ?  does anybody
*really* know the nitty gritty details of how these things are assigned?

-- 
Make everything as simple as possible, but no simpler.  -- Albert Einstein
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