Following the info on this site tried crossdev
http://www.funtoo.org/ODROID_U2
I did the same on gentoo last year and it worked perfectly

Here is the command :
crossdev -v -t armv7a-hardfloat-linux-gnueabi

fails with this

• Package 'cross-armv7a-hardfloat-linux-gnueabi/gcc-4.8.2-r2' NOT merged
• due to file collisions. If necessary, refer to your elog messages for
• the whole content of the above message.