At the end of reboot, I got kernel OOPS under 2.6.8-1.584 kernel on EM64T machine.
2.6.8-1.603 has the same problem. kernel died in find_isa_irq_pin.
Created attachment 105307 [details] A patch for reboot kernel panic linux-2.6.9-kexec.patch adds a call to find_isa_irq_pin in disable_IO_APIC. But find_isa_irq_pin is marked __init on x86-64, which leads to kernel panic. This patch should fix it.
It looks that this patch http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc4/2.6.9-rc4-mm1/broken-out/assign_irq_vector-section-fix.patch should be used.
fixed in current kernels.