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How can I find out that my CPU supports 64bit operating systems under Linux, e.g.: Ubuntu, Fedora?

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5 Answers 5

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I think the easiest way is by:

lscpu|grep "CPU op-mode"
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    This answer is the best. It shows you an explicit "32-bit" or "64-bit". I don't see why people choose the other answer over this one. You don't even need to grep anything. Just doing lscpu is so simple. If they don't have the lscpu command then I could see why they voted for the other one.
    – trusktr
    Commented Jan 4, 2014 at 21:12
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    The command that is the most portable across the largest variety of platforms is arguably the most useful. Commented Sep 9, 2014 at 9:06
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    I got '32-bit, 64-bit' What does it mean?
    – dstonek
    Commented Apr 10, 2016 at 13:31
  • It is a 64-bit machine running in 32-bit mode. Commented Oct 6, 2017 at 9:33
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Execute:

grep flags /proc/cpuinfo

Find 'lm' flag. If it's present, it means your CPU is 64bit and it supports 64bit OS. 'lm' stands for long mode.

Alternatively, execute:

grep flags /proc/cpuinfo | grep " lm "

Note the spaces in " lm ". If it gives any output at all, your CPU is 64bit.

Update: You can use the following in terminal too:

lshw -C processor | grep width

This works on Ubuntu, not sure if you need to install additional packages for Fedora.

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    Afaik it won't work if "lm" is the last flag in the line. :-)
    – peterh
    Commented Jun 27, 2016 at 12:38
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If your CPU is a 64bit one (x86-64), you can use it with a 64 bit OS.

Here is a list of 64bit CPUs: http://en.wikipedia.org/wiki/64-bit#Current_64-bit_microprocessor_architectures

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  • This is the ultra slow way, and not guaranteed to give you an answer.
    – trusktr
    Commented Jan 4, 2014 at 21:12
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    @trusktr: Yes. but all the other ways require Linux to be installed already. Not much help if you have an old Win32 machine and want to know if it will run a 64 bit *nix OS
    – Clifford
    Commented May 9, 2014 at 19:56
  • Same here. Found this useful, not having a running OS on the system in question to test it with. Commented Oct 28, 2014 at 0:38
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via this command dmidecode -t processor we can check the processor capability.

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  • That outputs a ton of other stuff, and splits "64-bit capable" on a different line than it's vague heading ("Characteristics"), so it's difficult to parse. Commented Oct 4, 2018 at 20:45
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Don't rely on the high scoring answers to this question because these methods are not always correct.

I've a computer with a Intel Atom N230 CPU which according to all of the tests mentioned is capable to support 64 bit OS'es.

According to http://en.wikipedia.org/wiki/Intel_Atom#32-bit_and_64-bit_hardware_support the CPU is not capable of running 64 bit OS'es. I've tried to install a 64 bit Linux OS and it indeed refuses to do so. Installing a 32 bit Linux OS works.

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