SMP support on Pentium D

Gareth Lee gareth.lee at
Sun Oct 29 23:45:48 UTC 2006

I'm trying to get dapper to run on a Pentium D (dual) processor CPU.
The standard 2.6.15 kernel boots fine, apparently detects all my
hardware, detects the second CPU but refuses to use it since it was
compiled with NR_CPUS = 1.  When I boot with the latest Knoppix release
(2.6.17 kernel) it detects and uses both the CPUs so there is no
fundamental incompatibility (... but I'd much rather run Kubuntu!)

I have tried using two alternative kernels from the repository,
the server kernel and the 686 SMP kernel.  In each case the bootup
starts fine, the ramdisk (apparently) loads and then the kernel hangs
with no clear error at the point it first mounts my (SATA?) root
partition.   There is nothing exotic about my hardware setup as far
as I can see (Pentium D 915 CPU on a recent Asus motherboard).

As a third alternative I tried obtaining the kernel source files,
compiling with the same configuration as the default kernel except
SMP was enabled and NR_CPUS set to 2.  This appears to build
and install a valid kernel and a set of modules but does not generate
a initrd file.  Consequently the boot process hangs since it does
not find the new modules in the standard initrd (and will not
apparently boot without a ramdisk).  I've found plenty of documentation
explaining how initrd works but no clear instructions about how to
build an initrd file and what I need to include in the initrd file
for use with Ubuntu (other than the new /lib/modules directory of
course).  I would expect the step to be automated but there does not
appear to be a make option for the kernel Makefile or any script to do
the job.

Since this is a problem that I would expect to have a relatively
simple solution I wondered if one of you folks can tell me what
I'm missing here!

Thanks in advance for any suggestions.

/Gareth Lee.
School of Electrical, Energy and Process Engineering
Murdoch University
Dixon Road, Rockingham 6168
Western Australia
Tel: +61-8-9360-7136
Fax: +61-8-9360-7104
Email: gareth.lee at

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