GCC Error while compiling for ARM

Question

I am getting the following error while trying to compile some code for an ARM Cortex-M4 using

gcc -mcpu=cortex-m4 arm.c  

`-mcpu=' is deprecated. Use `-mtune=' or '-march=' instead.
arm.c:1: error: bad value (cortex-m4) for -mtune= switch

I was following GCC 4.7.1 ARM options. Not sure whether I am missing some critical option. Any kickstart for using GCC for ARM will also be really helpful.

Answer 1

As starblue implied in a comment, that error is because you're using a native compiler built for compiling for x86 CPUs, rather than a cross-compiler for compiling to ARM.

GCC only supports a single general architecture type in any given compiler binary -- so, although the same copy of GCC can compile for both 32-bit and 64-bit x86 machines, you can't compile to both x86 and ARM with the same copy of GCC -- you need an ARM-specific GCC.

(As auselen suggests, getting a pre-built one will save you quite a lot of work, even if you're only using it as a starting point to get things set up. You need to have GCC, binutils, and a C library as a minimum, and those are all separate open-source projects that the pre-built versions have already done the work of combining. I'll recommend Sourcery CodeBench Lite since that's the one my company makes and I do think it's a fairly good one.)