top output, hyper-threading, and 2.5.69 kernel

["James D. Freels" <freelsjd@ornl.gov>]

I have a dual-Xeon (hyperthread) processor system on an Intel serverboard.  
When booted up under kernel 2.4.20, the top output indicates 4 processors are 
running.  I can toggle the output using the "1" key to show all processors 
combined, or 4 independent processors.

When I boot up under the 2.5.69 kernel (there does not appear to be a HT 
switch in the menuconfig, but I do have CONFIG_X86_HT=y in the .config file), 
the top command only shows 2 processors running.  

Questions:

Does this mean that hyperthreading is not enabled ?

If hyperthreading is enabled, and I have two physical processors, should the 
top command show 4 processors running ?

Why is the top output different between 2.4.20 and 2.5.69 ?

-- 
James D. Freels, Ph.D.
Oak Ridge National Laboratory
freelsjd@ornl.gov