Incorrect number of cores detected


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Hello everyone,

I have this Quad Quad-core machine running Hardy x86_64. Unfortunately, its only detecting 8 cores out of 16 cores. I tried a Fedora 8 x86_64 installation disk and did a cat /proc/cpuinfo in a ternimal and it detected all 16 cores. Do I need to enable any kernel flags when booting Hardy? Thanks in advance.

$ uname -a
Linux moriyama 2.6.24-19-generic #1 SMP Wed Aug 20 17:53:40 UTC 2008 x86_64 GNU/Linux

$ cat /proc/cpuinfo  | grep processor
processor	: 0
processor	: 1
processor	: 2
processor	: 3
processor	: 4
processor	: 5
processor	: 6
processor	: 7

 $ sudo lshw -C cpu
[sudo] password for tsiraj: 
  *-cpu:0				 
	   description: CPU
	   product: Quad-Core AMD Opteron(tm) Processor 8354
	   vendor: Advanced Micro Devices [AMD]
	   physical id: 3
	   bus info: cpu@0
	   version: 15.2.3
	   serial: To Be Filled By O.E.M.
	   slot: CPU 1
	   size: 2200MHz
	   capacity: 2200MHz
	   width: 64 bits
	   clock: 200MHz
	   capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp x86-64 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs
  *-cpu:1
	   description: CPU
	   product: Quad-Core AMD Opteron(tm) Processor 8354
	   vendor: Advanced Micro Devices [AMD]
	   physical id: 8
	   bus info: cpu@1
	   version: 15.2.3
	   serial: To Be Filled By O.E.M.
	   slot: CPU 2
	   size: 2200MHz
	   capacity: 2200MHz
	   width: 64 bits
	   clock: 200MHz
	   capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp x86-64 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs
  *-cpu:2
	   description: CPU
	   product: (To Be Filled By O.E.M.)
	   vendor: AMD
	   physical id: 4
	   bus info: cpu@2
	   version: 15.2.3
	   serial: To Be Filled By O.E.M.
	   slot: CPU 3
	   size: 2200MHz
	   capacity: 2200MHz
	   clock: 200MHz
  *-cpu:3
	   description: CPU
	   product: (To Be Filled By O.E.M.)
	   vendor: AMD
	   physical id: 10
	   bus info: cpu@3
	   version: 15.2.3
	   serial: To Be Filled By O.E.M.
	   slot: CPU 4
	   size: 2200MHz
	   capacity: 2200MHz
	   clock: 200MHz
  *-cpu:4 UNCLAIMED
	   physical id: 7
	   bus info: cpu@4
	   version: 15.2.3
  <snip />
  *-cpu:14 UNCLAIMED
	   physical id: 14
	   bus info: cpu@14
	   version: 15.2.3

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update... dmesg says its ignoring the missing 8 :(. Is there any limit on this?

tsiraj@moriyama: ~ $ dmesg | grep CPU
[	0.000000] Processor #0 (Bootup-CPU)
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] WARNING: NR_CPUS limit of 8 reached. Processor ignored.
[	0.000000] SMP: Allowing 8 CPUs, 0 hotplug CPUs
[	0.000000] PERCPU: Allocating 34656 bytes of per cpu data
[	0.000000] Initializing CPU#0
[   55.975125] CPU 0: aperture @ c000000 size 32 MB
[   56.289524] SLUB: Genslabs=12, HWalign=64, Order=0-1, MinObjects=4, CPUs=8, Nodes=4
[   56.398849] CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
[   56.398851] CPU: L2 Cache: 512K (64 bytes/line)
[   56.398854] CPU 0/0 -> Node 0
[   56.398856] CPU: Physical Processor ID: 0
[   56.398857] CPU: Processor Core ID: 0
<snip />

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Or use Fedora, which detected and used all cores without mucking with kernel source.

well... lets see how the recompile goes (still compiling...). I dont want to install fedora on that machine because we need a mix of different linux installations from different vendors. We already have fedora 7/8 in our build servers and we needed a server with gcc4.2, hence ubuntu. lets see how the custom kernel compilation goes first :)

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