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