HelenOS sources

BD_WRITE_BLOCKS   138 uspace/lib/device/src/bd.c 	aid_t req = async_send_3(exch, BD_WRITE_BLOCKS, LOWER32(ba),
BD_WRITE_BLOCKS   269 uspace/lib/device/src/bd_srv.c 		case BD_WRITE_BLOCKS:
HelenOS homepage, sources at GitHub