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I installed Ubuntu 12.04 LTS in a machine that has an Intel i3 processor. As far as I know, i3 processor is a multicore one and the OS should recognize 2 processors, just as Windows 7 does. Ubuntu isn't recognizing it though. Is it a known issue? Have I missed some configuration?

$ cat /proc/cpuinfo

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 37
model name      : Intel(R) Core(TM) i3 CPU         530  @ 2.93GHz
stepping        : 2
microcode       : 0x9
cpu MHz         : 2933.374
cache size      : 4096 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 11
wp              : yes
flags           : 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 ht tm pbe syscall nx rdtscp lm constant_tsc up arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm arat dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips        : 5866.74
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

[EDIT]

The output of

$ lscpu

is:

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                1
On-line CPU(s) list:   0
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 37
Stepping:              2
CPU MHz:               2933.196
BogoMIPS:              5866.39
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              4096K
NUMA node0 CPU(s):     0

[EDIT2]

Some additional info:

$ grep APIC /boot/config-3.2.0-29-generic
CONFIG_X86_X2APIC=y
CONFIG_X86_LOCAL_APIC=y
CONFIG_X86_IO_APIC=y
CONFIG_PCI_IOAPIC=y
CONFIG_KVM_APIC_ARCHITECTURE=y

From /var/log/kern.log :

Feb 22 08:37:27 MATTIDST002 kernel: [    0.000000] SMP: Allowing 1 CPUs, 0 hotplug CPUs
...
Feb 22 08:37:27 MATTIDST002 kernel: [    0.003953] CPU0: Thermal monitoring enabled (TM1)
Feb 22 08:37:27 MATTIDST002 kernel: [    0.003961] using mwait in idle threads.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.004000] SMP alternatives: switching to UP code
Feb 22 08:37:27 MATTIDST002 kernel: [    0.010870] Freeing SMP alternatives: 24k freed
Feb 22 08:37:27 MATTIDST002 kernel: [    0.010881] ACPI: Core revision 20110623
Feb 22 08:37:27 MATTIDST002 kernel: [    0.014752] ACPI: setting ELCR to 0200 (from cc60)
Feb 22 08:37:27 MATTIDST002 kernel: [    0.036996] ftrace: allocating 26998 entries in 106 pages
Feb 22 08:37:27 MATTIDST002 kernel: [    0.044302] weird, boot CPU (#0) not listed by the BIOS.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.044304] SMP motherboard not detected.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150902] SMP disabled
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150904] Performance Events: PEBS fmt1+, Westmere events, Intel PMU driver.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150911] ... version:                3
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150912] ... bit width:              48
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150914] ... generic registers:      4
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150915] ... value mask:             0000ffffffffffff
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150916] ... max period:             000000007fffffff
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150917] ... fixed-purpose events:   3
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150919] ... event mask:             000000070000000f
Feb 22 08:37:27 MATTIDST002 kernel: [    0.151032] NMI watchdog enabled, takes one hw-pmu counter.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.151050] Brought up 1 CPUs
Feb 22 08:37:27 MATTIDST002 kernel: [    0.151052] Total of 1 processors activated (5866.45 BogoMIPS).

[EDIT3]

Even more info:

$ grep SMP /boot/config-3.2.0-29-genericCONFIG_X86_64_SMP=y
CONFIG_USE_GENERIC_SMP_HELPERS=y
CONFIG_SMP=y
# CONFIG_X86_VSMP is not set
# CONFIG_MAXSMP is not set
CONFIG_PM_SLEEP_SMP=y
CONFIG_HAVE_TEXT_POKE_SMP=y
CONFIG_SCSI_SAS_HOST_SMP=y
CONFIG_VIDEO_VP27SMPX=m

Motherboard model: Asus P7H55-M

$ sudo lshw

I'm placing here just the info from last command regarding the motherboard:

  *-core
       description: Motherboard
       product: P7H55-M BR
       vendor: ASUSTeK Computer INC.
       physical id: 0
       version: X.0x
       serial: MS2222222222222222222222222
       slot: To Be Filled By O.E.M.
     *-firmware
          description: BIOS
          vendor: American Megatrends Inc.
          physical id: 0
          version: 0602
          date: 05/11/2011
          size: 64KiB
          capacity: 8128KiB
          capabilities: isa pci pnp apm upgrade shadowing escd cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification

Seems that my ubuntu installation is missing some modules, is it right? If yes, how can I install the correct ones? As this is a workstation setup and it toke a lot of time to setup this machine (setup development environment, bring up all network location, configure VPNs and so on), would be great if the solution does not involves things like format and reinstall all =p

share|improve this question
1  
Try the lscpu command instead of cat /proc/cpuinfo . It is more reliable (IMHO) because gather info form sysfs also. –  NikTh Feb 20 '13 at 18:29
    
Have you included the full output? On an older machine I see processor: 0 and a similar output for processor: 1. Although both have cpu cores: 2 unlike your output with cpu cores: 1. –  user25656 Feb 20 '13 at 18:31
    
@vasa1 yes, I included the full output –  Plinio.Santos Feb 21 '13 at 12:38

2 Answers 2

up vote 6 down vote accepted

It doesn't look like a module problem to me, the key looks to be in this line in the log:

Feb 22 08:37:27 MATTIDST002 kernel: [    0.044304] SMP motherboard not detected.
Feb 22 08:37:27 MATTIDST002 kernel: [    0.150902] SMP disabled

The kernel is detecting that your motherboard doesn't support SMP and then is disabling it. Without SMP only one processor can be active at a the same time.

In my experience this is usually caused by some BIOS option that Windows is just ignoring.

share|improve this answer
2  
@JavierRiveira I think you are right. My motherboard model is P7H55-M. Although this motherboard supports i3 530, Its BIOS has no mentions to SMP feature. –  Plinio.Santos Feb 22 '13 at 18:19
    
@javierRiveira spot on! :) –  Rinzwind Feb 22 '13 at 18:27
    
I didn't have a clue about this SMP. Thanks @JavierRiveira who illuminated me. PlinioSantos I think you can mark this answer as the correct.(IMHO) –  NikTh Feb 22 '13 at 22:00
1  
The BIOS has an option to reduce the number of active cores, check that it is set to 'All'. The BIOS must support SMP for Windows to detect both cores. You can also try to update the BIOS. –  Javier Rivera Feb 22 '13 at 23:34
1  
ACPI options are disabled in BIOS power settings. Everything worked fine after I enabled them. Thanks you all for help! @JavierRivera, As you helped a lot, add this info to you post and I will accept it as the right answer. Thanks again. –  Plinio.Santos Mar 6 '13 at 17:02

try $ lscpu , this will give all the cpu information .enter image description here

the lscpu command showing my corei5 processor have 32 and 64 bit both architecture and 4 CPU cores (0-3) also L1,L2,L3 cache memory .

share|improve this answer
    
I edited the original post for include the output of $ lscpu –  Plinio.Santos Feb 21 '13 at 13:16

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