J
Just follow LEDE instructions (Omega2 OS is a fork of LEDE):
https://lede-project.org/docs/guide-developer/compile_packages_for_lede_with_the_sdk
Short instruction:
Download SDK from https://downloads.lede-project.org/releases/17.01.4/targets/ramips/mt7688/
Unpack, enter, run: make menuconfig
In menu "Global Build Settings" unselect ALL (including "Cryptographically sign package list"
Exit menu (saving config)
Run: make (or make -j4 or make -j9 depending on how meny CPUs/Cores you have)
Voila, you got working SDK buildroot for ramips MT7688 (Omega2) Rest is the same as all others cross-compile buildroots (export env STAGING_DIR as $BUILDROOT/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/bin/, export PATH with STAGING_DIR as first in chain, etc).
If using e.g. make, remember to use variables for corss-compile:
CC=mipsel-openwrt-linux-musl-gcc
CCC=mipsel-openwrt-linux-musl-g++
CXX=mipsel-openwrt-linux-musl-g++
If you need configuration for IDEs (like Netbeans) let me know. All you need to do is setup new configuration with custom paths to buildroot compilators.
P.S. In future, remember to NOT download and use buildroots/SDKs from unofficial sources like dropbox, etc, it's a big security risk.