Backup current rom :
flashrom -p internal -r libreboot.rom -V
Remove old background :
./cbfstool libreboot.rom remove -n background.jpg
Print result :
./cbfstool libreboot.rom print
Add new background : (file must be named background.jpg)
./cbfstool libreboot.rom add -f background.jpg -n background.jpg -t raw
Print result :
./cbfstool libreboot.rom print
and flash the modified rom :
flashrom -p internal -w libreboot.rom -V
You can find cbfstool in
https://libreboot.org/release/stable/20160907/libreboot_r20160907_util.tar.xz
