Saturday, June 28, 2008

Processor support for 64 bit?

While chatting with a friend online the other day I became curious how one would determine if a processor supports 64bit and if the kernel is 64bits. Know the answer to first question could have helped me out a few weeks ago when I tried to install the x86_64 version of Fedora 9 on my wife's laptop. Unfortunately when I booted the install disk, the installer message stated that it was not 64bit capable.

To determine if you processor supports 64bit mode in Linux, the easiest thing to do is:
grep lm /proc/cpuinfo

The lm stands for long mode and it's in the cpu flags section. If more than one line is returned with the same information, the processor has multiple cores.

To determine if the OS kernel what instruction set it is running use:
uname -m

A value of x86_64 indicates that it is running the 64 bit extensions for Intel/AMD.

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