Following are the steps i am doing to compile for ARM64-generic

1. export BOARD=arm64-generic
2. ./setup_board --board=${BOARD} --nousepkg
3. ./build_packages --board=${BOARD}


With the second step i get the error: 
install_toolchain:171:main(), called: install_toolchain_in_board  
ERROR   :  install_toolchain:111:install_toolchain_in_board(), called: cross_get_version 'go' 
ERROR   :  install_toolchain:72:cross_get_version(), called: die 'Cannot find go' 

I still continue with the third step. In third step i cans ee lot of failures but in the end it exits saying:

ERROR   : Tue Nov 29 17:40:39 IST 2016
ERROR   :  PGID  PPID   PID     ELAPSED     TIME %CPU COMMAND
ERROR   :    10     6    10  1-01:42:51 00:00:00  0.0 -bash
ERROR   : 28331    10 28331    01:38:41 00:00:00  0.0  \_ /bin/bash ./build_packages --board=arm64-generic
ERROR   : 28331 28331 16289       00:00 00:00:00  0.0      \_ /bin/bash ./build_packages --board=arm64-generic
ERROR   : 28331 16289 16290       00:00 00:00:00  0.0          \_ ps f -o pgid,ppid,pid,etime,cputime,%cpu,command
ERROR   : Arguments of 28331: ./build_packages '--board=arm64-generic'
ERROR   : Backtrace:  (most recent call is last)
ERROR   :  build_packages:265:main(), called: die_err_trap  
ERROR   : 
ERROR   : Command failed:
ERROR   :   Command '( set -o pipefail; sudo -E "${EMERGE_CMD[@]}" "${EMERGE_FLAGS[@]}" "${PACKAGES[@]}" | tee "${tmpfile}" )' exited with nonzero code: 1


Any help would be appreciated. I havent made any changes to the build. So the overlay configs being picked is default. 
It uses the toolchain: arch64-cros-linux-gnu

Anything that i can try to make this work. 

Regards,
Vineet