AMD Phenom x3 only recognized as a single core

Asked by AFarris01

Hey all...ive got an issue with a computer i build for somebody, that is fairly serious, and i cant seem to find any relevent info on how to fix it. I've posted on the ubuntu forums also, but i havent gotten an answer yet, so im copying all the info here:

the computer in question has been built with an AMD Phenom x3 8400, BIOS is fully up-to-date and fully supports the x3 series, however ubuntu only recognizes one of the cpu's cores. Ive seen in the forums that people with similar problems were all people using older/different kernels, and the suggested fix has always been 'use the -generic kernel.' however, in this case, the generic kernel is already in use, and its not working... Heres the CLI outputs relevant to this problem:

user@Trill:~$ uname -a
Linux Trill 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC 2008 i686 GNU/Linux

user@Trill:~$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 16
model : 2
model name : AMD Phenom(tm) 8400 Triple-Core Processor
stepping : 2
cpu MHz : 2100.280
cache size : 512 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
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 sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs ts ttp tm stc 100mhzsteps hwpstate
bogomips : 3203.07
clflush size : 64

user@Trill:~$ dpkg -l | grep kernel

ii libdrm2 2.3.0-4ubuntu1 Userspace interface to kernel DRM services -
ii linux-generic Complete Generic Linux kernel
ii linux-headers-2.6.24-16 2.6.24-16.30 Header files related to Linux kernel version
ii linux-headers-2.6.24-16-generic 2.6.24-16.30 Linux kernel headers for version 2.6.24 on x
ii linux-headers-generic Generic Linux kernel headers
ii linux-image-2.6.24-16-generic 2.6.24-16.30 Linux kernel image for version 2.6.24 on x86
ii linux-image-generic Generic Linux kernel image
ii linux-restricted-modules-generic Restricted Linux modules for generic kernels
ii module-init-tools 3.3-pre11-4ubuntu5 tools for managing Linux kernel modules
ii nvidia-kernel-common 20051028+1ubuntu8 NVIDIA binary kernel module common files
ii udev 117-8 rule-based device node and kernel event mana

Basically i just want to know...does anybody know what this issue might be, or how i can fix it? i appreciate any thoughts!


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Sharar Ravitz (jewfro-macabbi) said :

does that kernel version support SMP (symmetric multi processing)? Perhaps you just need a kernel update.

Lots of info on kernels here:

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AFarris01 (afarris01) said :

user@Trill:~$ uname -a
Linux Trill 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC 2008 i686 GNU/Linux

ive been told that the generic kernel supports SMP, and its listed as such under the "uname -a" output above... so i'd assume that yes, the kernel supports it.

Im trying to do a kernel upgrade through the update manager, because i thought maybe that would help, but the downloads are going too slowly, because the computer is on a satellite internet connection. is it possible that if i upgrade it to the 2.6.24-19-generic kernel, that it might fix the problem?

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Trygve Vea (trygve-vea-gmail) said :


Seems like this is a "known" issue for Linux. Some people have experienced the problem in Arch as well (

Note that they solved it by installing a 64 bit distro.

I don't know if it's an option for you, but it has been known to solve the problem.

You most likely need to switch kernel to solve this problem.

I hope this helps :)

Regards, Trygve

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