Re: Still IRQ routing problems with VIA

[Axel Thimm <Axel.Thimm@physik.fu-berlin.de>]

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On Tue, Apr 10, 2001 at 01:38:32PM -0400, Jeff Garzik wrote:
> Axel Thimm wrote:
> > 0.7.[2,3] are the usb devices. BIOS (and 2.2 kernels) had them at IRQ 5.
> > 2.4 somehow picks the irq of the ethernet adapter, iqr 11, instead.
> > At least usb is then unusable.
> > As you say that you have the same board, what is the output of dump_pirq -
> > are your link values in the set of {1,2,3,5} or are they continuous 1-4? 
> > Maybe you are lucky - or better say, I am having bad luck :(
> Changing '#undef DEBUG' to '#define DEBUG 1' in arch/i386/kernel/pci-i386.h
> is also very helpful.  Can you guys do so, and post the 'dmesg -s 16384'
> results to lkml?  This includes the same information as dump_pirq, as well
> as some additional information.

OK, gzip-attached to this mail.

> Note that turning "Plug-n-Play OS" off in BIOS setup typically fixes many
> interrupt routing problems -- but Linux 2.4 should now have support for PNP
> OS:Yes.  Clearly there appear to be problems with that support on some Via
> hardware.

I had the problems with both settings (but I have tried so many patches and
kernels, that I cannot be sure about the combinations).

> Note that you should have "Plug-n-Play OS: Yes" when generated the
> requested 'dmesg' output.
O.K.

On Tue, Apr 10, 2001 at 01:01:07PM -0500, Jeff Garzik wrote:
> On Tue, 10 Apr 2001, Manuel A. McLure wrote:
> > This may be the difference - I always set "Plug-n-Play OS: No" on all my
> > machines. Linux works fine and it doesn't seem to hurt Windows 98 any.
> 
> Correct, it's perfectly fine to do that on all machines (not just Via).
> Users should also set "PNP OS: No" for Linux 2.2...
> 
> Other BIOS settings to verify:
> Assign IRQ to VGA: no (optional, but you probably don't need a VGA IRQ)
left to yes then, to keep the same BIOS settings/errors.
> Operating System: other (or Unix, depending on the BIOS)
n/a
> Memory hole: no
O.K.

> Unless you are using ISA cards, make sure all your PCI plug-n-play
> IRQ settings are set to "PCI/PnP" not "ISA/ICU".
O.K.

> hmmm, maybe I should write a Linux kernel BIOS guide/FAQ...

Yes, please!

And here are my FAQs with what I think are the answers (which means they are
possibly wrong, but then you get the idea, what some ppl might misunderstand):

Q) What does Plug-and-Play BIOS setting do?
A) It allows the OS to reassign IRQ/ports to devices (?)

Q) When should I turn it on or off?
A) If your BIOS is doing the right thing for you it's safe to turn it
   off. If you trust your OS more, turn it on. (?)

Q) Which OSes should I trust? What about multiboot systems?
A) Linux > 2.4.x, M$ xxx, etc. (?)

Q) What bad thing might happen, if a non P&P OS has in the BIOS a P&P setting
   or vice versa?
A) ... (?)

Thanks, Axel.
-- 
Axel.Thimm@physik.fu-berlin.de

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