Open Caraboot Makefile and change CONFIG_TOOLCHAIN_PREFIX to your buildroot binary path, i.e ```CONFIG_TOOLCHAIN_PREFIX=your_work_dir/buildroot/output/host/usr/bin/mips-linux- ```
```
cd Caraboot
vi/nano/gedit Makefile
```
Build:
```
make
```
The bootloader binary will be saved to ```bin/carambola2_u-boot.bin``` file.
You can now use this file to upgrade your bootloader on Carambola2 board (http://8devices.com/wiki/carambola:2:gettingstarted:bootloader-upgrade)