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.
Created attachment 110536 [details] serial console trace of bootup and panic
Per Dell weekly meeting (Dale), this is deferred to U2.
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".
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.