[Cialug] Where'd all the CPUs go?

[Nathan Smith]

I have a box with 8 Xeons that are hyperthreaded.  When I install Centos, cat/proc/cpuinfo shows 16 CPUs.  I just installed Ubuntu 8.04 server and it is showing 8 CPUs.

How can I determine if this is a difference between how cat /proc/cpu is reporting it or whether hyper threads are disabled on Ubuntu?

Dmesg also has a message that says:
Processor #1 15:2 APIC version 20
WARNING: NR_CPUS limit of 8 reached.  Processor Ignored.
ACPI: LAPIC (acpi_id[0x0a] lapic_id[0x03] enabled)

I found this page http://www.livingubuntu.com/?p=44 and tried these instructions along with just changing the kernel line in menu.1st.

I'm not sure what to check/try next.

-Nate