id	summary	reporter	owner	description	type	status	component	version	resolution	keywords	cc	guest	host
5728	CentOS 5.3 doesn't detect more than one CPU	Allan		"Linux guests cannot detect more than one cpu although Intel-VTx is enabled on the machine and there is no other hypervisor running on the box.

VBoxManage showvminfo vb340 | grep -i cpu
Number of CPUs:  2
Synthetic Cpu:   off
CPUID overrides: None

inside the guest:

cat /proc/cpuinfo 
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 15
model name	: Intel(R) Core(TM)2 CPU          6400  @ 2.13GHz
stepping	: 2
cpu MHz		: 2126.725
cache size	: 0 KB
physical id	: 0
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 0
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 5
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht constant_tsc up pni
bogomips	: 4253.45

There is only one!"	defect	closed	guest smp	VirtualBox 3.1.0	fixed			Linux	Linux