VirtualBox guest: 16 CPUs detected but only 1 online

I am running VirtualBox (using the Qiime image http://qiime.org/install/virtual_box.html) The physical hardware is a 32 core machine. The virtual machine in VirtualBox has been given 16 cores. When booting I get: Ubuntu 10.04.1 LTS Linux 2.6.38-15-server # grep . /sys/devices/system/cpu/* /sys/devices/system/cpu/kernel_max:255 /sys/devices/system/cpu/offline:1-15 /sys/devices/system/cpu/online:0 /sys/devices/system/cpu/possible:0-15 /sys/devices/system/cpu/present:0 /sys/devices/system/cpu/sched_mc_power_savings:0 # ls /sys/kernel/debug/tracing/per_cpu/ cpu0 cpu1 cpu10 cpu11 cpu12 cpu13 cpu14 cpu15 cpu2 cpu3 cpu4 cpu5 cpu6 cpu7 cpu8 cpu9 # ls /sys/devices/system/cpu/ cpu0 cpufreq cpuidle kernel_max offline online possible present probe release sched_mc_power_savings # echo 1 > /sys/devices/system/cpu/cpu6/online -su: /sys/devices/system/cpu/cpu6/online: No such file or directory So it seems it detects the resources for 16 CPUs, but it only sets one online. I have tested with another image that the VirtualBox host can run a guest with 16 cores. That works. So the problem is to trouble shoot the Qiime image to figure out why this guest image only detects 1 CPU.