What does the error "CPU you selected does not support x86-64 instruction set" mean?

Question

I installed Point Cloud Library from the ppa for in Ubuntu 11.10 x86_64 (including the dev packages, not necessarily relevant for the question but for the sake of completeness I am providing this detail). When I am trying to compile (make on a cmake generated make file) my own code which uses pcl I am getting the error CPU you selected does not support x86-64 instruction set. What does this error mean and what all should I check in order to remove the error?

Solution 1

This means that you're passing a flag to gcc which selects a CPU type that doesn't support 64bit. For example, maybe you're using a flag like -march=prescott or similar. What does your compile line look like? Some useful information about flags can be found on the Gentoo (where else?) wiki: http://en.gentoo-wiki.com/wiki/Safe_Cflags/Intel

Solution 2

Are you running on a 64 bit machine?

looks like the software is for 64 bit machines and you have a 32 bit processor.

Comments

[Anupam]

Output of uname -a: Linux ubuntu11 3.0.0-13-server #22-Ubuntu SMP Wed Nov 2 15:09:08 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

[Anupam]

Output of grep --color=always -iw lm /proc/cpuinfo shows the flag lm which means the processor is 64 bit capable.

[Arvind]

I got the same error by passing the flag -march=i486 to gcc in RHEL6 (64 bit). It get resolve by removing the same.

[cardiff space man]

cmake is doing something "clever" that causes the wrong march to be set, even though one is running on an x64 machine. It's more or less a cmake problem. (OP mentioned cmake in passing).