change the minimize disk free space limit to 8G
fix https://tower.im/projects/17ce1bc3f1f14999931c914377f5af62/todos/2a7b5fab0713495eaa383ab5eb5a1da6/
use erase_background helper instead rewrite one
use lib/log_to_file helper to record log instead of relying on the desktop file to redirect all output
clean no used code
remove update bootloader from C code
bind root directory to /target/host