I'm also getting this problem, this happens since natty, in maverick I didn't have this issue.
[ 0.013750] mce: CPU supports 6 MCE banks [ 0.013759] CPU0: Thermal monitoring enabled (TM2) [ 0.013764] using mwait in idle threads. [ 0.013794] SMP alternatives: switching to UP code [ 0.023066] ACPI: Core revision 20110112 [ 0.026216] ftrace: allocating 24314 entries in 96 pages [ 0.030059] Setting APIC routing to flat [ 0.030359] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 [ 0.136947] CPU0: Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz stepping 06 [ 0.140000] Performance Events: PEBS fmt0-, Core2 events, Intel PMU driver. [ 0.140000] PEBS disabled due to CPU errata. [ 0.140000] ... version: 2 [ 0.140000] ... bit width: 40 [ 0.140000] ... generic registers: 2 [ 0.140000] ... value mask: 000000ffffffffff [ 0.140000] ... max period: 000000007fffffff [ 0.140000] ... fixed-purpose events: 3 [ 0.140000] ... event mask: 0000000700000003 [ 0.140000] Brought up 1 CPUs [ 0.140000] Total of 1 processors activated (4267.04 BogoMIPS). [ 0.140000] devtmpfs: initialized -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/774037 Title: All CPU cores are not always detected -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
