gcc compilation flag

Question

can any body explain me why we use -m flag in gcc ? I run man gcc command result are quite unclear can any body explain me role of this flag in compilation? how to use -m flag its proper syntax? i need it because i'm running a auto generated makefile through make command but it shows an error which is following: cc1: error: unrecognized command line option "-m" can anybody explain what is that ?

Answer 1

-m is always followed by a machine-option, which will typically be machine-dependent. Common examples are -m32 and -m64 for selecting 32 bit and 64 bit builds on architectures which support both.

It sounds like you have an empty or uninitialised makefile variable somewhere.