Re: Kernel for Pentium 4 hyperthreading?

From: Dave Jones (
Date: Sun Dec 15 2002 - 08:44:08 EST

On Sat, Dec 14, 2002 at 08:11:45PM -0500, Scott Robert Ladd wrote:

> I've just received a new computer based on a 2.8 GHz Pentium 4 with
> hyper-threading enabled. Yes, HT is enabled in the BIOS; yes, /proc/cpuinfo
> shows the 'ht' flag; yes, I've compiled 2.4.20 (stock) with SMP and ACPI
> enabled.
> No, it doesn't work. cat /proc/cpuinfo reports a single CPU.

Note that just because /proc/cpuinfo shows 'ht' does not mean you can
use it in hyperthreaded mode. To do that, you also have to have >1
sibling in the physical package. Non-Xeon type P4's don't have the
extra sibling, so don't function as a hyperthreaded CPU.

> Can 2.4.20 handle a Pentium 4 (not Xeon, mind you) with HT? What could I be
> missing in my kernel build?

It's more a case of whats missing in your CPU package 8-)

| Dave Jones.
| SuSE Labs
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