Bug 146841

Summary: RHEL 4 U2: kernel panic when passing the 'nosmp' option to the x86_64 SMP kernel
Product: Red Hat Enterprise Linux 4 Reporter: Amit Bhutani <amit_bhutani>
Component: kernelAssignee: Jim Paradis <jparadis>
Status: CLOSED CURRENTRELEASE QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.0CC: davej, jbaron, peterm, riel, wwlinuxengineering
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: RHEL4-U4 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2006-07-13 20:19:21 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:
Bug Depends On:    
Bug Blocks: 170416    
Attachments:
Description Flags
serial console trace of bootup and panic none

Description Amit Bhutani 2005-02-02 00:13:07 UTC 
Description of problem:
Passing the 'nosmp' option to a SMP enabled kernel causes a kernel 
panic.

Version-Release number of selected component (if applicable):
kernel-smp-2.6.9-5.EL.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Install RHEL 4 x86_64 official RC1 on a SC1420
2. When grub menu is displayed, pick the smp kernel and edit the 
command line options to add 'nosmp' at the end of the kernel line
3. Allow the system to boot
  
Actual results:
kernel panic

Expected results:
System boots normally

Additional info:
I have not tried this on with the x86 arch yet.
Comment 1 Amit Bhutani 2005-02-02 00:13:58 UTC 
Created attachment 110536 [details]
serial console trace of bootup and panic
Comment 2 Susan Denham 2005-02-08 17:49:37 UTC 
Per Dell weekly meeting (Dale), this is deferred to U2.
Comment 10 Andrew 2005-11-14 16:10:55 UTC 
On dual Opteron hardware, booting the 32-bit Fedora Core 4 2.6.14-1.1637_FC4smp
Linux kernel with "nosmp" results in a similar problem.  After "OK, booting the
kernel" the system stops after repeating 7 times the message "IOAPIC[0]: Invalid
reference to IRQ 0".
Comment 13 Jim Paradis 2006-07-13 20:19:21 UTC 
The kernel panic was fixed in U4 as a result of the fixes for Bug 174627 and Bug
176612.  That said, some systems still may not work with "nosmp" because it also
disables the IO APIC (See Comment 10).  The workaround for this is to use the
"noapic" flag along with "nosmp".  This is a known issue upstream as well.

Closing as CURRENTRELEASE for having fixed the panic.