[U-Boot] gcc version error ?

I was following this step to create a u-boot image

*https://wiki.archlinux.org/index.php/Banana_Pi#Install_basesystem_to_a_SD_ca... https://wiki.archlinux.org/index.php/Banana_Pi#Install_basesystem_to_a_SD_card*

when I executed this line:

*$ make -j4 ARCH=arm CROSS_COMPILE=arm-none-eabi-*

I got this error message.

**** Your GCC is older than 6.0 and is not supported* *arch/arm/config.mk:66 http://config.mk:66: recipe for target 'checkgcc6' failed* *make: *** [checkgcc6] Error 1*

but my gcc is already above 6.0, why?

*$ gcc --version* *gcc (Ubuntu 7.3.0-16ubuntu3~16.04.1) 7.3.0*

Regards, YuChing