LINUX_ECHOPRT
bts->c_lflag |= cvtto_bsd_mask(lt->c_lflag, LINUX_ECHOPRT, ECHOPRT);
lt->c_lflag |= cvtto_linux_mask(bts->c_lflag, ECHOPRT, LINUX_ECHOPRT);
bts->c_lflag |= cvtto_bsd_mask(lts->c_lflag, LINUX_ECHOPRT, ECHOPRT);
lts->c_lflag |= cvtto_linux_mask(bts->c_lflag, ECHOPRT, LINUX_ECHOPRT);