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I have a Lenovo Ideapad Y510. I have always used 32bit OS in it. Yesterday I came across this detail of my laptop and it says processor of my laptop is 64bit (hope I have not misinterpret anything) so I did some google and I came across this question. As I have Ubuntu installed I tried command in last answer (i.e lscpu) and output was same with some differences. My main concern are first two lines of output i.e.

Architecture:          i686
CPU op-mode(s):        32-bit, 64-bit

My question is does my CPU support 64bit OS? As per this link I think yes.

If yes then shouldn't be the output of lscpu be like samothing as below as far as I know i686 stands for 32bit. Correct me if I am wrong.

Architecture:          AMD64
CPU op-mode(s):        64-bit
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Of course, you could have just downloaded a 64-bit "live" CD, and just tried... ;-) –  DevSolar Jul 19 '12 at 8:53

3 Answers 3

up vote 4 down vote accepted

Yes it does support 64bit OS.

It has two entries because on 64-bit processor you can install both 64 and 32 bit ubuntu.

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thanx for clarifying the two entries meaning. –  Sandy Jul 19 '12 at 7:34
    
Do all 64-bit processors run 32-bit Ubuntu? E.g. IA-64 Itanium? SPARC64? PA-RISC? s/64-bit/x86-64/ –  RedGrittyBrick Jul 19 '12 at 9:18
    
@RedGrittyBrick it is actually answered in the itanium wiki article you linked :) You CAN run 32 bit ubuntu on those, but they will be painfully slow. –  Sandro Dzneladze Jul 20 '12 at 7:28

To know if the installed Ubuntu is of 32 or 64 bits:

  • getconf LONG_BIT
  • uname -m

If it shows i686 or i386 it means 32-bits.
If it shows x86_64 it means 64-bits.

If the CPU is 32 bit, Ubuntu must also be 32-bit.
If the CPU is 64 bit it can work with 64- or 32-bit OSes. We can choose to install 32- or 64-bit Ubuntu.

To know if the CPU is of 32 or 64 bits:

  • grep -w lm /proc/cpuinfo
    • If we see lm in red, the CPU supports 64 bit. Otherwise it is 32 bits.
  • sudo lshw | grep “description: CPU” -A 12 | grep width
    • It says clearly what we want to know.
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The output you saw from lscpu means your processor (Google says it has an Intel Core 2 Duo) is capable of 32-bit and 64-bit, but that you are currently running a 32-bit operating system.

The output from a 64-bit operating system is:

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit

You should be fine to install a 64-bit operating system if you wish.

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