On Mon, Nov 30, 2020 at 12:15:51PM -0800, Mychaela Falconia wrote: > > I'm adding a new tty port flag that can be used to suppress the > > assertion of DTR/RTS to signal DTE readiness on open named NORDY. > > Eventually we can expose it through termios to match HUPCL that controls > > the behaviour on final close. For now I'm only adding a sysfs interface > > but that also allows control over these signals on first open. > > I don't see how exposing this new flag via termios would be of any use > (it's a chicken and egg problem: one needs to open the tty device in > order to do termios ioctls on it, and if that initial open triggers > DTR/RTS hardware actions, then the end user is still screwed), but > making this flag accessible for setting and clearing via sysfs is a > good idea. Yeah, as I mentioned in the other thread a termios flag would not be sufficient for your use case, but there could be other applications that are more tolerant but still want control after first open. I believe this is also the way Win32, which you referred to earlier, works. Johan
