FreeBSD 8.0, Intel Xeon E5530, Dell R410, only 2 cores available

[Hoang V.D. | Creative Solutions GmbH]

Hello,

We just purchased a Dell PowerEdge R410 server with this CPU: Intel Xeon Processor E5530

http://ark.intel.com/Product.aspx?id=37103

According to specs the CPU has 4 cores, 8 Hyper-Threading threads, however after installing 
FreeBSD 8.0 (amd64), only 2 cores (4 SMT threads) were recognized by the kernel. Here is the
relevant dmesg extract:

-----------------
Copyright (c) 1992-2009 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 8.0-RELEASE-p2 #0: Tue Jan  5 21:11:58 UTC 2010
    root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Xeon(R) CPU           E5530  @ 2.40GHz (2394.01-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x106a5  Stepping = 5
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x9ce3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,DCA,SSE4.1,SSE4.2,POPCNT>
  AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
  AMD Features2=0x1<LAHF>
  TSC: P-state invariant
real memory  = 8589934592 (8192 MB)
avail memory = 8247111680 (7865 MB)
ACPI APIC Table: <DELL   PE_SC3  >
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
FreeBSD/SMP: 1 package(s) x 2 core(s) x 2 SMT threads
 cpu0 (BSP): APIC ID: 16
 cpu1 (AP): APIC ID: 17
 cpu2 (AP): APIC ID: 18
 cpu3 (AP): APIC ID: 19
ioapic1: Changing APIC ID to 1
ioapic0 <Version 2.0> irqs 0-23 on motherboard
ioapic1 <Version 2.0> irqs 32-55 on motherboard
...
-----------------

We was expecting to see "1 package(s) x 4 core(s) x 2 SMT threads" and 8 usable "cpus" 
Instead. According to sysctl:

kern.smp.cpus: 4
kern.smp.maxcpus: 32
hw.ncpu: 4
machdep.hlt_cpus: 0

We have made no change to the BIOS settings (all settings are set by default by Dell).
Could anyone help us with an explanation for this issue? 

Best regards,
Hoang V.D.