g++ Compile from x86 for ARM Cortex

i want to compile from my workstation for a ARM Cortex-9a. I found this gcc options for a freescale iMX6q ARM processor

If I'm right, it's possible to do this ? I've using

gcc --version
gcc (SUSE Linux) 4.8.1 20130909 [gcc-4_8-branch revision 202388]

and want to compile with the flags listed (here)

g++ -O3 -mtune=cortex-a9 main.cc -o main.o -c
main.cc:1:0: error: bad value (cortex-a9) for -mtune= switch
 #include <stdio.h>
 ^

do i really need the toolchains ? I thought that they are only for "simpler" usage ?

EDIT for me, using crosstools-ng is the best & easiest way