Re: 2.6.25.3: serial problem (minicom)

R.L. Horn
2008-06-15T07:05:06Z

On Sat, 14 Jun 2008, Alan Cox wrote:

> What happens after you go from B0->Banythingelse should depend on the
> termios settings at that point. This sounds like a bug therefore.
>
> If you want that behaviour intentionally set B0, after this termios
> call then set CLOCAL before changing the baud back.

I'm not seeing any change in behavior with different combinations of
CLOCAL. As it happens, minicom sets CLOCAL first thing so as to keep
SIGHUP signals from being generated.

But, then, what is the relationship between CLOCAL and DTR/RTS supposed to
be? Presumably, it should prevent a SIGHUP from being raised when DSR
goes low, but beyond that, it all seems rather ill-defined. Throw in B0,
which the SUS strongly implies should unconditionally lower DTR and RTS,
and the CRTSCTS flag, and the waters really get murky. It looks to me
like the only thing you can say for certain is that CLOCAL will cause DSR
to be ignored...and for anything else you're on your own.

Mind you, all this just suggests that POSIX kinda sucks, which is hardly
an earth-shattering revelation.

> I'll take a look at this next week.

It would be much appreciated. Thanks.