linker warning: obj/simtrace/dfu_sniffer.o: In function `usb_send_data': /media/data/work/simtrace2/simtrace2/firmware/libcommon/source/sniffer.c:338: warning: undefined reference to `putchar' Change-Id: I934f3fcb474d4046e921511a024c3a0b8533c782