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I am currently running a 32-bit OS, but I'm not really sure if I have to. According to some articles on the Web, there are no flags in my output that indicate that my CPU is a 64-bit. But according to articles describing the Athlon II X2 250, such as this one, it should be 64-bit processor. I've never been much of a hardware person, so I don't know if this article necessarily means that mine is a 64-bit, or mine is just a subset of some family of processors, some of which are 64-bit.

I am slightly worried because there is nothing in the hardware information that very specifically states Data bus size: 32 or 64. How do I know for sure?

This is the output from my /proc/cpuinfo

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 6
model name  : AMD Athlon(tm) II X2 250 Processor
stepping    : 3
microcode   : 0x10000b6
cpu MHz     : 1800.000
cache size  : 1024 KB
physical id : 0
siblings    : 2
core id     : 0
cpu cores   : 2
apicid      : 0
initial apicid  : 0
fdiv_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 nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock nrip_save vmmcall
bogomips    : 5984.90
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 1
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 6
model name  : AMD Athlon(tm) II X2 250 Processor
stepping    : 3
microcode   : 0x10000b6
cpu MHz     : 2300.000
cache size  : 1024 KB
physical id : 0
siblings    : 2
core id     : 1
cpu cores   : 2
apicid      : 1
initial apicid  : 1
fdiv_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 nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock nrip_save vmmcall
bogomips    : 5984.90
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

marked as duplicate by Michael Homer, Archemar, Gilles, G-Man, taliezin Jul 2 '15 at 7:54

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • No, not the currently installed Linux Kernel, that's 32-bit. I'm saying maybe I don't have to install a 32-bit if my processor supports (is) 64-bit. – Digital Ninja Jul 2 '15 at 5:10
  • 1
    Ah yes true, sorry. However, I think the answer is still in that thread, under To determine if the hardware is capable of running a 64-bit kernel. – Sparhawk Jul 2 '15 at 5:16
  • Right, so that's actually one of the answers I found prior, and it says I need a lm flag, which I don't have. However the "processor specifications" say that it's 64-bit. – Digital Ninja Jul 2 '15 at 5:20
  • @ImNotMike You have the lm flag; it's right there on the "flags" line. – Michael Homer Jul 2 '15 at 6:34
up vote 2 down vote accepted

This processor can run 64 bit versions (I compared your CPU flags with mine that is running 64 bit, and none of the differences are important features).

You can make sure for yourself by burning an installation CD of a 64bit version of your OS (or make a USB stick) and boot that. Modern versions will either not boot or check for 64 bit and won't normally install if your CPU doesn't support 64 bit.

Google for "AMD Athlon(tm) II X2 250" you'll find out http://www.amd.com/en-us/products/processors/desktop/athlon-ii# which says:

Simultaneous 32-bit and 64-bit Computing

AMD64 technology enables a breakthrough approach to 64-bit computing that doubles the number of registers in the processor and allows PC users to use today’s 32-bit software applications while enabling them to also use the next generation of 64-bit applications.

So you can install a 64 bits Operating system, like an amd64 (or x86-64) flavor of Linux. And if you have -or may later have- more than 4Gbytes of RAM (which is likely) you'll better install a 64 bits variant (to enable some processes to have more than 4Gbytes of address spaces, to use almost all the RAM if needed)

You might keep a 32 bits OS if you have few RAM (4Gbytes or less), since 32 bits OS and applications are using slightly less memory than 64 bits ones; however they are then unable to process a lot of data, i.e. to have processes with more than 3Gbytes of address space).

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