"spurious 8259A interrupt: IRQ7"

"spurious 8259A interrupt: IRQ7"

[Martin A. Brooks]

I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
according to /proc/pci.

Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.

Any pointers appreciated.

Regards

Martin A. Brooks.

Re: 'spurious 8259A interrupt: IRQ7'

[Martin A. Brooks]

> i get the same thing, its some device off the south bridge generating
> an int, but if you dont service it it seems to go away, dont worry
> about it. :)

ACK.  Thanks for the pointer.

Regards

Martin A. Brooks.

Re: "spurious 8259A interrupt: IRQ7"

[Marek Pętlicki]

Martin A. Brooks wrote:
> I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
> according to /proc/pci.
> 
> Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.

same thing here:

1GHz Athlon TB (currently on 900MHz due to stability problems), 128MB
DDR SDRAM

$ lspci
00:00.0 Host bridge: VIA Technologies, Inc.: Unknown device 3099
00:01.0 PCI bridge: VIA Technologies, Inc.: Unknown device b099
00:0a.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139
(rev 10)
00:11.0 ISA bridge: VIA Technologies, Inc.: Unknown device 3074
00:11.1 IDE interface: VIA Technologies, Inc. VT82C586 IDE [Apollo] (rev
06)
00:11.2 USB Controller: VIA Technologies, Inc. VT82C586B USB (rev 18)
00:11.3 USB Controller: VIA Technologies, Inc. VT82C586B USB (rev 18)
00:11.4 USB Controller: VIA Technologies, Inc. VT82C586B USB (rev 18)
00:11.5 Multimedia audio controller: VIA Technologies, Inc.: Unknown
device 3059 (rev 10)
01:00.0 VGA compatible controller: nVidia Corporation Vanta [NV6] (rev
15)

regards

-- 
Marek Pętlicki <marpet@linuxpl.org>
Linux User ID=162988

Re: "spurious 8259A interrupt: IRQ7"

[Alan Cox]

> I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
> according to /proc/pci.
> 
> Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.
> 
> Any pointers appreciated.

IRQ7 is asserted when the PIC sees an interrupt but nobody appears to be
generating it when it looks.

Re: "spurious 8259A interrupt: IRQ7"

[Andreas Steinmetz]

As far as I remember this was talked about earlier. Different mobos, chipsets,
processor brands, but always IRQ 7. /me wonders. At least it doesn't do any
harm (got this message on nearly all or all of my systems).

On 27-Nov-2001 Alan Cox wrote:
>> I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
>> according to /proc/pci.
>> 
>> Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.
>> 
>> Any pointers appreciated.
> 
> IRQ7 is asserted when the PIC sees an interrupt but nobody appears to be
> generating it when it looks.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

Andreas Steinmetz
D.O.M. Datenverarbeitung GmbH

Re: 'spurious 8259A interrupt: IRQ7'

[Martin A. Brooks]

> As far as I remember this was talked about earlier. Different mobos,
> chipsets, processor brands, but always IRQ 7. /me wonders.

In my research before posting, a common thread seemed to be the presence of
a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Martin A. Brooks

Re: 'spurious 8259A interrupt: IRQ7'

[Andreas Steinmetz]

On 27-Nov-2001 Martin A. Brooks wrote:
>> As far as I remember this was talked about earlier. Different mobos,
>> chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?
> 

Yes (epic100).

> Martin A. Brooks
> 
> 
> 
> 

Andreas Steinmetz
D.O.M. Datenverarbeitung GmbH

Re: 'spurious 8259A interrupt: IRQ7'

[Martin A. Brooks]

> Something I should have added to my post is that I have a Tulip based
> NIC  from Netgear.  But I believe something is definitely amiss with
> Athlon based  machines and Tulip cards and compiled in SMP support.

Mine is a UP box.

Martin A. Brooks.

Re: 'spurious 8259A interrupt: IRQ7'

[Pascal Schmidt]

On Tue, 27 Nov 2001, Martin A. Brooks wrote:

> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Me, on an ALi Magik 1 chipset board using the ALi 1533 southbridge. Always 
happens during the first ten minutes of uptime.

-- 
Ciao, Pascal

-<[ pharao90@tzi.de, netmail 2:241/215.72, home http://cobol.cjb.net/) ]>-

Re: 'spurious 8259A interrupt: IRQ7'

[Andreas Steinmetz]

On 27-Nov-2001 Martin A. Brooks wrote:
>> Something I should have added to my post is that I have a Tulip based
>> NIC  from Netgear.  But I believe something is definitely amiss with
>> Athlon based  machines and Tulip cards and compiled in SMP support.
> 
> Mine is a UP box.

All of my boxes are UP, too. PII, PIII, Athlon TB. Various mobos.

> 
> Martin A. Brooks.
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> Please read the FAQ at  http://www.tux.org/lkml/
> 

Andreas Steinmetz
D.O.M. Datenverarbeitung GmbH

Re: 'spurious 8259A interrupt: IRQ7'

[Bernd Bartmann]

Martin A. Brooks wrote:

>>As far as I remember this was talked about earlier. Different mobos,
>>chipsets, processor brands, but always IRQ 7. /me wonders.
>>
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?


I don't have any tulip card in my system but also got this message twice

last week during backup to my Onstream DI-30 FAST ide tape streamer. 
Please have a look at my bug report to RedHat Bugzilla:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=56630

-- 
Dipl.-Ing. (FH) Bernd Bartmann <Bernd.Bartmann@sohanet.de>
SoHaNet Technology GmbH / Kaiserin-Augusta-Allee 10-11 / 10553 Berlin
Software / Hardware / Netzwerke * Entwicklung / Verkauf / Wartung
Fon: +49 30 214783-44 / Fax: +49 30 214783-46

Re: 'spurious 8259A interrupt: IRQ7'

[Martin A. Brooks]

> With IO Apic support included ? If you are using an AMD/VIA combo
> chipset board that would explain it

Yup

CONFIG_X86_UP_APIC=y
CONFIG_X86_UP_IOAPIC=y
CONFIG_X86_LOCAL_APIC=y
CONFIG_X86_IO_APIC=y

Martin A. Brooks.

Re: 'spurious 8259A interrupt: IRQ7'

[Jan Niehusmann]

On Tue, Nov 27, 2001 at 02:38:13PM -0000, Martin A. Brooks wrote:
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Yes, on ASUS A7V133 board, Duron 800, Realtek network card.

Jan

Re: 'spurious 8259A interrupt: IRQ7'

[Alan Cox]

> > Something I should have added to my post is that I have a Tulip based
> > NIC  from Netgear.  But I believe something is definitely amiss with
> > Athlon based  machines and Tulip cards and compiled in SMP support.
> 
> Mine is a UP box.

With IO Apic support included ? If you are using an AMD/VIA combo chipset
board that would explain it

Re: 'spurious 8259A interrupt: IRQ7'

[Ian Molton]

On a sunny Tue, 27 Nov 2001 14:38:13 -0000 (GMT) Martin A. Brooks gathered
a sheaf of electrons and etched in their motions the following immortal
words:

> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence
of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

No, but I have a tulip in my box and I see it :)

seems to be harmless.

Re: 'spurious 8259A interrupt: IRQ7'

[mike_phillips]

> In my research before posting, a common thread seemed to be the presence 
of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Does the same on my laptop, but only after the 3C575 cardbus adapter is 
plugged in (using the 3c59x driver).

Mike

Re: 'spurious 8259A interrupt: IRQ7'

[Ian Molton]

On a sunny Tue, 27 Nov 2001 14:59:34 -0000 (GMT) Martin A. Brooks gathered
a sheaf of electrons and etched in their motions the following immortal
words:

> 
> > With IO Apic support included ? If you are using an AMD/VIA combo
> > chipset board that would explain it
> 
> Yup
> 
> CONFIG_X86_UP_APIC=y
> CONFIG_X86_UP_IOAPIC=y
> CONFIG_X86_LOCAL_APIC=y
> CONFIG_X86_IO_APIC=y

Same here.

what /is/ IOAPIC? I always turned it on, but never bothered to check up on
what it is (its safe to just have it, right?)

Re: 'spurious 8259A interrupt: IRQ7'

[Andreas Steinmetz]

On 27-Nov-2001 Alan Cox wrote:
>> > Something I should have added to my post is that I have a Tulip based
>> > NIC  from Netgear.  But I believe something is definitely amiss with
>> > Athlon based  machines and Tulip cards and compiled in SMP support.
>> 
>> Mine is a UP box.
> 
> With IO Apic support included ? If you are using an AMD/VIA combo chipset
> board that would explain it

IO Apic, yes. But the PII/PIII systems are BX or I810/I815.

> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

Andreas Steinmetz
D.O.M. Datenverarbeitung GmbH

Re: 'spurious 8259A interrupt: IRQ7'

[Adam Schrotenboer]

On Tuesday 27 November 2001 09:38, Martin A. Brooks wrote:
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
>
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?
>
Yes. RTL 8139.

> Martin A. Brooks
>
>

-- 
tabris

   Life is pain. Anybody that tells you differently is selling something.

                                    William Goldman, "The princess bride"

Re: 'spurious 8259A interrupt: IRQ7'

[Andi Kleen]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> > > Something I should have added to my post is that I have a Tulip based
> > > NIC  from Netgear.  But I believe something is definitely amiss with
> > > Athlon based  machines and Tulip cards and compiled in SMP support.
> > 
> > Mine is a UP box.
> 
> With IO Apic support included ? If you are using an AMD/VIA combo chipset
> board that would explain it

I see it on a SIS 735 board too (with IO-APIC enabled).

-Andi

Re: 'spurious 8259A interrupt: IRQ7'

[Adam Schrotenboer]

On Tuesday 27 November 2001 10:01, Alan Cox wrote:
> > > Something I should have added to my post is that I have a Tulip based
> > > NIC  from Netgear.  But I believe something is definitely amiss with
> > > Athlon based  machines and Tulip cards and compiled in SMP support.
> >
> > Mine is a UP box.
>
> With IO Apic support included ? If you are using an AMD/VIA combo chipset
> board that would explain it
With it turned on, but no IOAPIC (figured I did have one. But it never 
worked.) present. AMD 751/756.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
tabris

   Due to management cuts, the light at the end of the tunnel will now be
   switched off.

                                                                 Graffiti

Re: 'spurious 8259A interrupt: IRQ7'

[Peter Wächtler]

"Martin A. Brooks" schrieb:
> 
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?
> 

Yes. dmfe.o (Davicom "almost" 2114x)

Athlon with VIA82686_A_. Perhaps it's the Southbridge ?

Re: 'spurious 8259A interrupt: IRQ7'

[Joachim Franek]

Am Dienstag, 27. November 2001 15:38 schrieb Martin A. Brooks:
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
>
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?
>
> Martin A. Brooks
>
>

yes on my laptop: Mitac Mi6020 (with suse73)

Joachim Franek
Email: joachim.franek@t-online.de
www.de-franek.de

Re: 'spurious 8259A interrupt: IRQ7'

[Pascal Schmidt]

On Tue, 27 Nov 2001, Peter Wächtler wrote:

> Athlon with VIA82686_A_. Perhaps it's the Southbridge ?

No, also happens on my ALi only board, no VIA chips involved.

-- 
Ciao, Pascal

-<[ pharao90@tzi.de, netmail 2:241/215.72, home http://cobol.cjb.net/) ]>-

Re: 'spurious 8259A interrupt: IRQ7'

[lk]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=X-UNKNOWN, Size: 1011 bytes --]


Hello,

I recently enabled UP IOAPIC, and only then did I start seeing this
message.  No hardware changes.

via 82c686 with a 3com 905b.

Seems to only pop up with apic (just recompiled without it and haven't
gotten the message again).


Regards,
Adrian



On Tue, 27 Nov 2001, Peter [iso-8859-1] Wächtler wrote:

> "Martin A. Brooks" schrieb:
> >
> > > As far as I remember this was talked about earlier. Different mobos,
> > > chipsets, processor brands, but always IRQ 7. /me wonders.
> >
> > In my research before posting, a common thread seemed to be the presence of
> > a tulip card in the machine.  Has anyone seen this on a non-tulip box?
> >
>
> Yes. dmfe.o (Davicom "almost" 2114x)
>
> Athlon with VIA82686_A_. Perhaps it's the Southbridge ?
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

Re: "spurious 8259A interrupt: IRQ7"

[bart]

Hi,

Iv seen this on a Intel BX chipset Pentium2 266 box, and on a VIA KT266A
1ghz Athlon box.

BaRT

Re: 'spurious 8259A interrupt: IRQ7'

[Alex Davis]

I don't have a tulip card in my machine, and I still
have the problem. I only have spurious ints. with my
Athlon-based systems: my Intel-based machines don't
exhibit them. I think we should compile a list of boards
that have the problem and try to find some commonality.

-Alex

Martin A. Brooks" schrieb:
> 
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?
> 


__________________________________________________
Do You Yahoo!?
Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month.
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Re: "spurious 8259A interrupt: IRQ7"

[Luigi Genoni]

I think a couple of months ago I was discussing on this mail list the same
problem with ac. From then I saw this message with every kernel on any VIA
based MB i tryed (for athlon, for K6 and so on). It is harmless, but
noisy. of course, disabling IOAPIC the problem does always disappear, but
it's again noisy.

On 28 Nov 2001, bart wrote:

> Hi,
>
> Iv seen this on a Intel BX chipset Pentium2 266 box, and on a VIA KT266A
> 1ghz Athlon box.
>
> BaRT
>
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

Re: 'spurious 8259A interrupt: IRQ7'

[Tom Diehl]

On Tue, 27 Nov 2001, Martin A. Brooks wrote:

> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Yes, all kinds of machines none of which have a tulip in them. 

-- 
......Tom		Dysfunction The Only Consistent Feature of All
tdiehl@rogueind.com	of Your Dissatisfying Relationships is You.

Re: "spurious 8259A interrupt: IRQ7"

[vda]

On Tuesday 27 November 2001 12:20, Andreas Steinmetz wrote:
> As far as I remember this was talked about earlier. Different mobos,
> chipsets, processor brands, but always IRQ 7. /me wonders. At least it
> doesn't do any harm (got this message on nearly all or all of my systems).
>
> On 27-Nov-2001 Alan Cox wrote:
> >> I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
> >> according to /proc/pci.
> >>
> >> Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.
> >>
> >> Any pointers appreciated.
> >
> > IRQ7 is asserted when the PIC sees an interrupt but nobody appears to be
> > generating it when it looks.

I see it too on my home system (Duron 650 + VIA chipset)
--
vda

Re: "spurious 8259A interrupt: IRQ7"

[Sebastian Dröge]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi,
I've had this very message, too.
System is a PII 350, MSI-6151 motherboard with Intel BX chipset
But it's a time ago I had it ;)
When I remember right it was the one kernel I've enabled APIC/IO-APIC but I'm
not sure. Right now I have no APIC/IO-APIC enabled.
I'll test it later the day
Bye


Am Dienstag, 27. November 2001 19:30 schrieb vda:
 On Tuesday 27 November 2001 12:20, Andreas Steinmetz wrote:
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders. At least it
> > doesn't do any harm (got this message on nearly all or all of my
> > systems).
> >
> > On 27-Nov-2001 Alan Cox wrote:
> > >> I get this with 2.4.16 vanilla, though. IRQ 7 appears to be unassigned
> > >> according to /proc/pci.
> > >>
> > >> Machine is a 1ghz Athlon on a VIA VT82C686 mobo and a DEC 21140 NIC.
> > >>
> > >> Any pointers appreciated.
> > >
> > > IRQ7 is asserted when the PIC sees an interrupt but nobody appears to
> > > be generating it when it looks.
>
> I see it too on my home system (Duron 650 + VIA chipset)

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE8A94fvIHrJes3kVIRAr3SAKCdcisZj7yfj7mENPSEc2h/Bq+AlQCfVC5i
/wx+DcuyM4OH29GinxEEnYI=
=LDkl
-----END PGP SIGNATURE-----

Re: 'spurious 8259A interrupt: IRQ7'

[Vojtech Pavlik]

On Tue, Nov 27, 2001 at 02:38:13PM -0000, Martin A. Brooks wrote:
> > As far as I remember this was talked about earlier. Different mobos,
> > chipsets, processor brands, but always IRQ 7. /me wonders.
> 
> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Yep. No tulip in my Athlon Classic, and I've seen it twice today.

-- 
Vojtech Pavlik
SuSE Labs

Re: 'spurious 8259A interrupt: IRQ7'

[Peter Bornemann]

On Tue, 27 Nov 2001, Alex Davis wrote:

> I think we should compile a list of boards
> that have the problem

If You are collecting examples:
I am seeing it on a regular base during boot-up, sometimes also later on.
I have an  Athlon 700 on an Asus K7V Mobo with VIA Apollo chipset and 512
MB RAM. Otherwise, the box is  rock solid.

Hope this helps

Peter B

          .         .
          |\_-^^^-_/|
          / (|)_(|) \
         ( === X === )
          \  ._|_.  /
           ^-_   _-^
              °°°

Re: 'spurious 8259A interrupt: IRQ7'

[Jurjen Oskam]

On Tue, Nov 27, 2001 at 02:38:13PM -0000, Martin A. Brooks wrote:

> In my research before posting, a common thread seemed to be the presence of
> a tulip card in the machine.  Has anyone seen this on a non-tulip box?

Yup: standard SuSE 7.3 install on an Asus A7V266-E motherboard (VIA KT266A
chipset, 512 MB DDR, Athlon XP).

Just recently installed Linux on that machine (yesterday evening) so I
don't even know what kernel version SuSE 7.3 uses. :-( If needed, I can try
other kernels.

-- 
      Jurjen Oskam * http://www.stupendous.org/ for PGP key * Q265230
    8:39am  up 30 days, 23:33,  1 user,  load average: 0.15, 0.03, 0.01

Re: 'spurious 8259A interrupt: IRQ7'

[szonyi calin]

Hi
Cx 486,  no pci, no network card, same message.
>From my experience in PC hardware i know that irq 7 is
usually asigned to the parallel port.
I know a windoze box which didn't print until i set up
in bios that paralel port has irq7.

Bye

=====
*********************************************************
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                 *  votre signature ne peut pas comporter 
                 plus de 600 caractères ni occuper plus de 
                 sept lignes. 
Another way to say: Welcome to Yahoo! ^^^
**********************************************************

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RE: 'spurious 8259A interrupt: IRQ7'

[Wouter van Bommel]

I also see this messages on various machines each with different hardware.
I see it on 1 cpu Athlon machines, but also on 2 CPU pentium III machines.

- Wouter

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org
> [mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of szonyi calin
> Sent: Wednesday November 28, 2001 9:59 AM
> To: linux-kernel@vger.kernel.org
> Subject: Re: 'spurious 8259A interrupt: IRQ7'
>
>
> Hi
> Cx 486,  no pci, no network card, same message.
> >From my experience in PC hardware i know that irq 7 is
> usually asigned to the parallel port.
> I know a windoze box which didn't print until i set up
> in bios that paralel port has irq7.
>
> Bye
>
> =====
> *********************************************************
>                 Désolé, un problème s'est produit :
>                  *  votre signature ne peut pas comporter
>                  plus de 600 caractères ni occuper plus de
>                  sept lignes.
> Another way to say: Welcome to Yahoo! ^^^
> **********************************************************
>
> __________________________________________________________
> Obtenez votre adresse @yahoo.ca gratuite et en français !
> courriel.yahoo.ca
> -
> To unsubscribe from this list: send the line "unsubscribe
> linux-kernel" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

RE: 'spurious 8259A interrupt: IRQ7'

[PVotruba]

Also noticed on via686a, duron, geforce2mx, realtek 8029 10 Mbps NIC, ES
1371 sound card, zip drive on paralell port.. Later I'll try to disable
paralell port in bios and see if that strange message disappears...


	--- previous message follows: 
> On Tue, Nov 27, 2001 at 02:38:13PM -0000, Martin A. Brooks wrote:
> 
> > In my research before posting, a common thread seemed to be the presence
> of
> > a tulip card in the machine.  Has anyone seen this on a non-tulip box?
> 
> Yup: standard SuSE 7.3 install on an Asus A7V266-E motherboard (VIA KT266A
> chipset, 512 MB DDR, Athlon XP).
> 
> Just recently installed Linux on that machine (yesterday evening) so I
> don't even know what kernel version SuSE 7.3 uses. :-( If needed, I can
> try
> other kernels.
> 
> -- 
>       Jurjen Oskam * http://www.stupendous.org/ for PGP key * Q265230
>     8:39am  up 30 days, 23:33,  1 user,  load average: 0.15, 0.03, 0.01
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: 'spurious 8259A interrupt: IRQ7'

[Martin Eriksson]

----- Original Message -----
From: "Wouter van Bommel" <wvanbommel@jasongeo.com>
To: "'szonyi calin'" <caszonyi@yahoo.com>; <linux-kernel@vger.kernel.org>
Sent: Wednesday, November 28, 2001 10:31 AM
Subject: RE: 'spurious 8259A interrupt: IRQ7'


> I also see this messages on various machines each with different hardware.
> I see it on 1 cpu Athlon machines, but also on 2 CPU pentium III machines.

Now here is a strange thing: I see it in my brothers ADSL linux router
syslog *before* they moved it to another place in their room two weeks ago.
Now it never appears, and before it appeared about once a day. They are
using 2.4.13 with ext3.

I'm starting to believe it has something to do with the parallel port being
unconnected, thus sending random signals to the mobo causing an interrupt?
If this is the case it is very possible that it has to do with correct
grounding also...

_____________________________________________________
|  Martin Eriksson <nitrax@giron.wox.org>
|  MSc CSE student, department of Computing Science
|  Umeå University, Sweden

> > -----Original Message-----
> > From: linux-kernel-owner@vger.kernel.org
> > [mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of szonyi calin
> > Sent: Wednesday November 28, 2001 9:59 AM
> > To: linux-kernel@vger.kernel.org
> > Subject: Re: 'spurious 8259A interrupt: IRQ7'
> >
> >
> > Hi
> > Cx 486,  no pci, no network card, same message.
> > >From my experience in PC hardware i know that irq 7 is
> > usually asigned to the parallel port.
> > I know a windoze box which didn't print until i set up
> > in bios that paralel port has irq7.
> >
> > Bye

Re: 'spurious 8259A interrupt: IRQ7'

[Piter Punk]

> On Tue, Nov 27, 2001 at 02:38:13PM -0000, Martin A. Brooks wrote:
> 
>>>As far as I remember this was talked about earlier. Different mobos,
>>>chipsets, processor brands, but always IRQ 7. /me wonders.
>>>
>>In my research before posting, a common thread seemed to be the presence of
>>a tulip card in the machine.  Has anyone seen this on a non-tulip box?


I have the same message in my home computer too (Athlon, A7A266 ALi chipset, 
256Mb DDR, Realtek 8139). But i don't see any problems...

-- 
   ____________
  / Piter PUNK \_____________________________________________________
|                                                                   |
|      |        E-Mail: piterpk@terra.com.br         (personal)     |
|     .|.               roberto.freires@gds-corp.com (professional) |
|     /V\                                                           |
|    // \\      UIN: 116043354  Homepage: www.piterpunk.hpg.com.br  |
|   /(   )\                                                         |
|    ^`~'^         ----> Slackware Linux - The Best One! <----      |
|   #105432                                                         |
`-------------------------------------------------------------------'

Re: 'spurious 8259A interrupt: IRQ7'

[Chris Meadors]

On Wed, 28 Nov 2001, Martin Eriksson wrote:

> I'm starting to believe it has something to do with the parallel port being
> unconnected, thus sending random signals to the mobo causing an interrupt?
> If this is the case it is very possible that it has to do with correct
> grounding also...

Actually I believe way back there was a discussion about this same
message, Alan Cox said he thought it was caused by bad parallel ports.

That said I see it on 2 Athlon boxes with VIA chipsets.  One I had never
seen the message until I removed the parallel port QuickCam I had hooked
up.

-Chris
-- 
Two penguins were walking on an iceberg.  The first penguin said to the
second, "you look like you are wearing a tuxedo."  The second penguin
said, "I might be..."                         --David Lynch, Twin Peaks

Re: 'spurious 8259A interrupt: IRQ7'

[Richard B. Johnson]

On Wed, 28 Nov 2001, Chris Meadors wrote:

> On Wed, 28 Nov 2001, Martin Eriksson wrote:
> 
> > I'm starting to believe it has something to do with the parallel port being
> > unconnected, thus sending random signals to the mobo causing an interrupt?
> > If this is the case it is very possible that it has to do with correct
> > grounding also...
> 
> Actually I believe way back there was a discussion about this same
> message, Alan Cox said he thought it was caused by bad parallel ports.
> 
> That said I see it on 2 Athlon boxes with VIA chipsets.  One I had never
> seen the message until I removed the parallel port QuickCam I had hooked
> up.
> 

IRQ7 is usually connected to the parallel port. If there is no driver
installed, that expects interrupts, you could end up with this
annoying message because the printer status bits are all ORed into
that IRQ line. You can disable this with software, though, and it
might be a good idea.

          outb(0, BASE+2);

... where BASE is 0x278, 0x378, 0x3bc, etc.. the printer ports.

Also, a catch-all for confused interrupt controllers is IRQ7. Even
without a parallel port, you can still get an occasional spurious
interrupt. I think the kernel should have an interrupt handler for
this interrupt that does nothing except ACK the interrupt and
keep its mouth shut.  The request_irq() procedure should ignore
the fact that it is "in use", and let any driver have it without
sharing it.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

Re: 'spurious 8259A interrupt: IRQ7'

[Piter Punk]

Richard B. Johnson wrote:

>
> IRQ7 is usually connected to the parallel port. If there is no driver
> installed, that expects interrupts, you could end up with this
> annoying message because the printer status bits are all ORed into
> that IRQ line. You can disable this with software, though, and it
> might be a good idea.
> 
>           outb(0, BASE+2);
> 
> ... where BASE is 0x278, 0x378, 0x3bc, etc.. the printer ports.


Hmmmm. I have a driver installed! I use a printer in my parallel port and i 
need lp module is installed.

But... i am go to see if this message appears only on boot (before i load 
the module) or appears all time...

 
> Also, a catch-all for confused interrupt controllers is IRQ7. Even
> without a parallel port, you can still get an occasional spurious
> interrupt. I think the kernel should have an interrupt handler for
> this interrupt that does nothing except ACK the interrupt and
> keep its mouth shut.  The request_irq() procedure should ignore
> the fact that it is "in use", and let any driver have it without
> sharing it.

-- 
   ____________
  / Piter PUNK \_____________________________________________________
|                                                                   |
|      |        E-Mail: piterpk@terra.com.br         (personal)     |
|     .|.               roberto.freires@gds-corp.com (professional) |
|     /V\                                                           |
|    // \\      UIN: 116043354  Homepage: www.piterpunk.hpg.com.br  |
|   /(   )\                                                         |
|    ^`~'^         ----> Slackware Linux - The Best One! <----      |
|   #105432                                                         |
`-------------------------------------------------------------------'

Re: "spurious 8259A interrupt: IRQ7"

[Alan Cox]

> (not one of the updated 2.96's). With that build (a 2.4.8 kernel), I

2.4.8 isnt a very reliable kernel

> PS: Is gcc-2.96.99 currently in RawHide as good (or better ;) as
> gcc-2.95.3 for kernel builds? Jakub Jelinek seems to be doing a good job
> on it...

I use 2.96 from RH 7.2 for all my builds. 2.95.3 is probably the better
tested compiler for general things though

Re: "spurious 8259A interrupt: IRQ7"

[Ishan Oshadi Jayawardena]

Alan Cox wrote:

> IRQ7 is asserted when the PIC sees an interrupt but nobody appears to be
> generating it when it looks.
> -

	I had the same symptoms on an uniprocessor IBM PC300GL (pretty standard
pc, 32MB ram, 333MHz celeron [pre-coppermine], 82371AB PIIX E-IDE/ACPI
chips,
Intel Motherboard, 66MHz bus), S3 Trio3D (IBM integrated - **does that
mean anything to you? XFree86-SVGA doesn't work on it, but XFree86-S3
version 4.0.1
-RH 7.0- seems to work fine with the s3virge driver) AGP graphics board
(2MB
vram) plus an Avance ALS4000 card are all I've got. I was worried
because
I don't have any 8259A's on my motherboard and this led me to kgcc.
	The problem occured _only_ when I, unknowingly, used RH 7.0's gcc 2.96
(not one of the updated 2.96's). With that build (a 2.4.8 kernel), I
learnt my lesson when linux got utterly stuck twice in a single day.
Since then, builds with standard gcc's recommended by Linus (egcs/kgcc
&& gcc 2.95.3) have seen the end of this problem. The message came up
during normal use, not in a special situation such as bootup, etc.
	Hope this has been of some help.

PS: Is gcc-2.96.99 currently in RawHide as good (or better ;) as
gcc-2.95.3 for kernel builds? Jakub Jelinek seems to be doing a good job
on it...

	- ioj

-----------------------------------------------------------------------
	"And King Parakramabahu sent men with a bushel of Rice each to every
corner of the land, and the people returned saying that a bushel of Rice
could
be sold for two cents. Then the King knew that not enough food or his
people was being produced. He built tanks of water and cultivated more
land. Again deployed men. Now they returned saying that no one would
take the grain even
for free. The King was satisfied."

Re: "spurious 8259A interrupt: IRQ7"

[Luca Montecchiani]

On my "old" system this message appear randomly after the boot process
when my machine always try to make a ISDN connection with my provider.
Sometimes appears in the kernel boot process... funny.

IOAPIC : not set
kernel : 2.4.x
CPU    : K6-2 450
Chipset: 

00:00.0 Host bridge: Acer Laboratories Inc. [ALi] M1541 (rev 04)
00:01.0 PCI bridge: Acer Laboratories Inc. [ALi] M5243 (rev 04)
00:07.0 ISA bridge: Acer Laboratories Inc. [ALi] M1533 PCI to ISA Bridge [Aladdin IV] (rev b4)
00:08.0 Network controller: Elsa AG QuickStep 1000 (rev 01)
00:09.0 USB Controller: VIA Technologies, Inc. VT82C586B USB (rev 04)
00:0a.0 Multimedia audio controller: Trident Microsystems 4DWave DX (rev 02)
00:0f.0 IDE interface: Acer Laboratories Inc. [ALi] M5229 IDE (rev 20)
01:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G100 [Productiva] AGP (rev 02)


grep -A1 -B1 spurious /var/log/messages :

May 12 10:04:05 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
May 12 10:04:44 localhost kernel: spurious 8259A interrupt: IRQ7.
May 12 10:04:44 localhost ipppd[529]: Modem hangup
--
May 23 21:10:33 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
May 23 21:28:29 localhost kernel: spurious 8259A interrupt: IRQ7.
May 23 21:49:49 localhost -- MARK --
--
May 30 20:15:57 localhost -- MARK --
May 30 20:16:31 localhost kernel: spurious 8259A interrupt: IRQ7.
May 30 20:35:57 localhost -- MARK --
--
Jun  9 15:16:37 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
Jun  9 15:16:42 localhost kernel: spurious 8259A interrupt: IRQ7.
Jun  9 15:17:28 localhost ipppd[529]: Modem hangup
--
Jun 25 19:01:16 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
Jun 25 19:01:20 localhost kernel: spurious 8259A interrupt: IRQ7.
Jun 25 19:02:06 localhost ipppd[529]: Modem hangup
--
Jun 28 05:33:12 localhost ipppd[529]: remote IP address XXX.YYY.XXX.59
Jun 28 05:36:02 localhost kernel: spurious 8259A interrupt: IRQ7.
Jun 28 05:36:30 localhost ipppd[529]: Modem hangup
--
Jul  3 21:33:19 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
Jul  3 21:33:30 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul  3 21:39:04 localhost ipppd[529]: Modem hangup
--
Jul  5 07:31:04 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
Jul  5 07:32:22 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul  5 07:38:02 localhost ipppd[529]: Modem hangup
--
Jul  9 23:18:48 localhost Wmaker: Hi luca, welcome to localhost
Jul  9 23:24:02 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul  9 23:38:25 localhost -- MARK --
--
Jul 12 22:11:20 localhost -- MARK --
Jul 12 22:22:53 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 12 22:51:20 localhost -- MARK --
--
Jul 15 22:21:34 localhost ipppd[529]: remote IP address XXX.YYY.XXX.54
Jul 15 22:21:39 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 15 22:22:07 localhost ipppd[529]: Modem hangup
--
Jul 16 21:26:53 localhost ipppd[530]: remote IP address XXX.YYY.XXX.54
Jul 16 21:26:58 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 16 21:30:24 localhost ipppd[530]: Modem hangup
--
Jul 17 20:11:57 localhost ipppd[530]: Connect[0]: /dev/ippp0, fd: 7
Jul 17 20:13:45 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 17 20:13:53 localhost Wmaker: Hi luca, welcome to luca.home.net
--
Jul 23 20:08:51 localhost kernel: loop: loaded (max 8 devices)
Jul 23 20:14:38 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 23 20:25:42 localhost -- MARK --
--
Jul 25 19:21:29 localhost ipppd[530]: remote IP address XXX.YYY.XXX.59
Jul 25 19:22:03 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 25 19:22:03 localhost ipppd[530]: Modem hangup
--
Jul 26 07:55:53 localhost -- MARK --
Jul 26 07:57:43 localhost kernel: spurious 8259A interrupt: IRQ7.
Jul 26 08:09:42 localhost init: Switching to runlevel: 6
--
Aug 14 17:41:53 localhost kernel: HiSax: Approved with Eicon Technology Diva 2.01 PCI cards
Aug 14 17:41:53 localhost kernel: spurious 8259A interrupt: IRQ7.
Aug 14 17:41:53 localhost kernel: HiSax: Approved with Sedlbauer Speedfax + cards
--
Aug 22 08:49:40 localhost kernel: Adding Swap: 264592k swap-space (priority -1)
Aug 22 08:49:40 localhost kernel: spurious 8259A interrupt: IRQ7.
Aug 22 08:49:41 localhost cron[439]: (CRON) STARTUP (fork
ok)                                                                                           
--                                                                                                                                                      
Nov 10 10:28:15 localhost lircd-0.6.4[576]: caught
signal                                                                                               
Nov 10 10:31:08 localhost kernel: spurious 8259A interrupt:
IRQ7.                                                                                       
Nov 10 10:42:00 localhost CRON[743]: (root) CMD ([ -x /usr/sbin/cronloop ] && /usr/sbin/cronloop Hourly)

Re: "spurious 8259A interrupt: IRQ7"

[Zwane Mwaikambo]

Ishan wrote...
>I don't have any 8259A's on my motherboard and this led me to kgcc.

The 8259A is actually Intel's Programmable Interrupt Controller. Which
guessing from your PC specs you probably have.

Zwane Mwaikambo

Re: 'spurious 8259A interrupt: IRQ7' -> read the 8259 datasheet !

[Gunther Mayer]

"Richard B. Johnson" wrote:
> 
> On Wed, 28 Nov 2001, Chris Meadors wrote:
> 
> > On Wed, 28 Nov 2001, Martin Eriksson wrote:

...
... rumours deleted (e.g. "printer status bits are all ORed into irq7")
...

>From "Harris Semiconductor 82C59A Interrupt Controller Datasheet":
  If no interrupt request is present at step 4 of either sequence
  (i.e., the request was too short in duration), the 82C59A will
  issue an interrupt level 7. 

1. The irq controller sees an interrupt.
2. The irq controller signals "there is _some_ interrupt" to the cpu.
3. The CPU acks via INTA
4. The irq controller looks if the irq is still there
   (and signals IRQ7 if the line is no longer active).

You have some device which doesn't keep the IRQ raised long enough !
(or the CPU doesn't service the irq for a too long time and the 
 edge triggered irq is de-asserted or even serviced by a polling routine)

Re: 'spurious 8259A interrupt: IRQ7' -> read the 8259 datasheet !

[Richard B. Johnson]

On Fri, 30 Nov 2001, Gunther Mayer wrote:

> "Richard B. Johnson" wrote:
> > 
> > On Wed, 28 Nov 2001, Chris Meadors wrote:
> > 
> > > On Wed, 28 Nov 2001, Martin Eriksson wrote:
> 
> ...
> ... rumours deleted (e.g. "printer status bits are all ORed into irq7")
> ...
> 
> >From "Harris Semiconductor 82C59A Interrupt Controller Datasheet":
>   If no interrupt request is present at step 4 of either sequence
>   (i.e., the request was too short in duration), the 82C59A will
>   issue an interrupt level 7. 
> 
> 1. The irq controller sees an interrupt.
> 2. The irq controller signals "there is _some_ interrupt" to the cpu.
> 3. The CPU acks via INTA
> 4. The irq controller looks if the irq is still there
>    (and signals IRQ7 if the line is no longer active).
> 
> You have some device which doesn't keep the IRQ raised long enough !
> (or the CPU doesn't service the irq for a too long time and the 
>  edge triggered irq is de-asserted or even serviced by a polling routine)
> -

In the first place I HAVE not only read the data-sheet, but probably
was one of the first to report the affect when first observed in
the days of XT machines, before there was a second cascaded controller.

If the effect was caused by the transient condition you describe, then
the second controller would also suffer from the same problem, i.e.,
its "IRQ7" is really IRQ15 when cascaded.

The problems with "spurious IRQ7" reared its head when the new
boards and cards became available with CMOS inputs with weak and/or
no pull-ups. If you leave a connector off the printer port, the
status bits will float and generate interrupts on IRQ7. You can
stop this, as previously taught, by disabling the IRQ enable
by writing bit 4 of the control-port (offset 1) to zero. You do
this on all known printer ports and you no longer get the kernel
messages.

So, before you issue another "rumors deleted" know-it-all retort,
observe that you can "mysteriously" stop the problem by mucking
with the printer control port. This certainly seems to disprove
your INTA theory.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

Re: 'spurious 8259A interrupt: IRQ7' -> read the 8259 datasheet !

[Martin Eriksson]

----- Original Message -----
From: "Gunther Mayer" <Gunther.Mayer@t-online.de>
To: <root@chaos.analogic.com>
Cc: "Chris Meadors" <clubneon@hereintown.net>; "Martin Eriksson"
<nitrax@giron.wox.org>; <linux-kernel@vger.kernel.org>; <martin@jtrix.com>
Sent: Friday, November 30, 2001 8:28 PM
Subject: Re: 'spurious 8259A interrupt: IRQ7' -> read the 8259 datasheet !


> "Richard B. Johnson" wrote:
> >
> > On Wed, 28 Nov 2001, Chris Meadors wrote:
> >
> > > On Wed, 28 Nov 2001, Martin Eriksson wrote:
>
> ...
> ... rumours deleted (e.g. "printer status bits are all ORed into irq7")
> ...
>
> >From "Harris Semiconductor 82C59A Interrupt Controller Datasheet":
>   If no interrupt request is present at step 4 of either sequence
>   (i.e., the request was too short in duration), the 82C59A will
>   issue an interrupt level 7.

Uhmm... call me slow, but I don't get it 100%... so this message has NOTHING
to do with the LPT IRQ7? It just signals this because IRQ7 is the lowest
priority IRQ on the 8259A?

>
> 1. The irq controller sees an interrupt.
> 2. The irq controller signals "there is _some_ interrupt" to the cpu.
> 3. The CPU acks via INTA
> 4. The irq controller looks if the irq is still there
>    (and signals IRQ7 if the line is no longer active).

Umm.. so again.. this means that the IRQ is not held long enough for the PIC
to actually recognize *what* IRQ was asserted?

>
> You have some device which doesn't keep the IRQ raised long enough !
> (or the CPU doesn't service the irq for a too long time and the
>  edge triggered irq is de-asserted or even serviced by a polling routine)

Thanks a bunch for clearing this up (this far)!!

When we get a firm indication on the 'problem', could the "spurious 8259A
interrupt" message be de-obfuscated into something less unsettling?

PS. Real Men (tm) never reads the datasheets!

_____________________________________________________
|  Martin Eriksson <nitrax@giron.wox.org>
|  MSc CSE student, department of Computing Science
|  Umeå University, Sweden

Re: 'spurious 8259A interrupt: IRQ7' -> read the 8259 datasheet !

[Gunther Mayer]

"Richard B. Johnson" wrote:
> 
> On Fri, 30 Nov 2001, Gunther Mayer wrote:
> 
> > "Richard B. Johnson" wrote:
> > >
> > > On Wed, 28 Nov 2001, Chris Meadors wrote:
> > >
> > > > On Wed, 28 Nov 2001, Martin Eriksson wrote:
> >
> > ...
> > ... rumours deleted (e.g. "printer status bits are all ORed into irq7")
> > ...
> >
> > >From "Harris Semiconductor 82C59A Interrupt Controller Datasheet":
> >   If no interrupt request is present at step 4 of either sequence
> >   (i.e., the request was too short in duration), the 82C59A will
> >   issue an interrupt level 7.
> >
> > 1. The irq controller sees an interrupt.
> > 2. The irq controller signals "there is _some_ interrupt" to the cpu.
> > 3. The CPU acks via INTA
> > 4. The irq controller looks if the irq is still there
> >    (and signals IRQ7 if the line is no longer active).
> >
> > You have some device which doesn't keep the IRQ raised long enough !
> > (or the CPU doesn't service the irq for a too long time and the
> >  edge triggered irq is de-asserted or even serviced by a polling routine)
> > -
> 
> In the first place I HAVE not only read the data-sheet, but probably
> was one of the first to report the affect when first observed in
> the days of XT machines, before there was a second cascaded controller.
> 
> If the effect was caused by the transient condition you describe, then
> the second controller would also suffer from the same problem, i.e.,
> its "IRQ7" is really IRQ15 when cascaded.

The slave could ignore T3-T7 when it detects a spurious irq and
signal IRQ7 to the CPU nevertheless !

> 
> The problems with "spurious IRQ7" reared its head when the new
> boards and cards became available with CMOS inputs with weak and/or
> no pull-ups. If you leave a connector off the printer port, the
> status bits will float and generate interrupts on IRQ7. You can
> stop this, as previously taught, by disabling the IRQ enable
> by writing bit 4 of the control-port (offset 1) to zero. You do
> this on all known printer ports and you no longer get the kernel
> messages.
> 
> So, before you issue another "rumors deleted" know-it-all retort,
> observe that you can "mysteriously" stop the problem by mucking
> with the printer control port. This certainly seems to disprove
> your INTA theory.

Get some data sheet about the parallel port to see:
"Bit 4: A 1 in this position allows an interrupt to occur when nACK changes from low to high."
So the status bits are _not_ ORed.

I agree, a floating nACK would provoke IRQ7 (or IRQ5 when configured for this).

On the parport list a user reports he gets some spurious irq7 on probing a PCI
card configured to IRQ12 ! So this card seems to trigger the 8259 generated IRQ7,
which proves the case described in the 8259 datasheet happens in reality.

In summary IRQ7 can be raised:
a) by parallel port due to floating nACK
b) by 8259 itself on some transient condition (this could be further be proved by
   suspending INTA and forcefully raising and releasing an irq, don't know if this is feasible)

Your proposition to set Bit4=0 would allow to rule out case b), of course.
It seems the inital reporter can reproduce the conditions ...