Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

Bug 30240

Summary:	IRQ conflict in installation kernel makes SCSI controller unusable
Product:	[Retired] Red Hat Linux	Reporter:	jfm2
Component:	kernel	Assignee:	Ingo Molnar <mingo>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Brock Organ <borgan>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	7.1
Target Milestone:	---
Target Release:	---
Hardware:	i386
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2001-04-16 11:54:25 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description jfm2 2001-03-02 01:28:08 UTC

My CD reader is attached to an SCSI controller.  The controller  (a Symbios
53c875) happens to use the same IRQ 9 than my ethernet card.   Both devices
are PCI.  When I try to install there is amessage telling there is an IRQ
conflict and from then installation goes so slowly to be completely
unusable: itr takes over five minutes to get a shell prompt in console 2. 
 Box is a K6/2 450 with 128 megs of RAM.

I installed through a disk install (disk is IDE) and the production kernel
does not have problems with both devices using the same IRQ.

Comment 1 Michael K. Johnson 2001-03-02 03:06:41 UTC

Which ethernet card and driver?

Comment 2 jfm2 2001-03-02 22:29:42 UTC

NE2000 PCI clone.  Driver is NE2K PCI.  But the problem is not in the driver. 
The problem is in PCI-related code. The kernel in kerrnel-BOOT (ie the one used
for installation) does not know how to handle peripherals using the same IRQ. 
cat /proc/pci shows that the SCSI controller has been identified as master
capable and the ethernet as not master capable (both correct) but kernel is not
able to  handle IRQ sharing.   The regular production kernel (kernel-i586 RPM)
has no problem sharing IRQs.

Comment 3 Michael K. Johnson 2001-03-05 17:43:23 UTC

Could you please type the *exact* message you get telling you about
the IRQ conflict?  That way we can look for it.

Comment 4 jfm2 2001-03-08 22:11:26 UTC

<4> IRQ 9 Routing conflict in PIRQ table device 00:07:2

Comment 5 Michael K. Johnson 2001-03-13 04:00:53 UTC

The closest I can find is "IRQ routing conflict in pirq table for device..."

Ingo, can you shed any light on this?

Comment 6 Ingo Molnar 2001-04-16 09:38:15 UTC

does this still happen if you use the vanilla 2.4.3 kernel? There were some
fixes in this area. The pirq routing conflict is not necesserily a unrecoverable
problem, but it's indeed a sign of BIOS wackiness in the PCI area.

Comment 7 jfm2 2001-04-16 11:54:21 UTC

Could be a BIOS problem but it works with the normal (ie not install kernel).  I
think the Wolverine kernel had not the "Enable IRQ sharing" compil falg enabled
while the production kernel had it enabled