On Fri, Jun 24, 2022 at 11:42:09PM +0300, Ilpo Järvinen wrote: > ADDRB in termios indicates 9th bit addressing mode is enabled. In this > mode, 9th bit is used to indicate an address (byte) within the > communication line. ADDRB can only be enabled/disabled through > ->rs485_config() that is also responsible for setting the destination and > receiver (filter) addresses. [...] > --- a/include/uapi/asm-generic/termbits-common.h > +++ b/include/uapi/asm-generic/termbits-common.h > @@ -46,6 +46,7 @@ typedef unsigned int speed_t; > #define EXTA B19200 > #define EXTB B38400 > > +#define ADDRB 0x20000000 /* address bit */ > #define CMSPAR 0x40000000 /* mark or space (stick) parity */ > #define CRTSCTS 0x80000000 /* flow control */ > You may want to consider submitting a patch to the Linux man-pages project to document the newly introduced bit: https://www.kernel.org/doc/man-pages/patches.html https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man3/termios.3 Thanks, Lukas