Date: Tue, 14 Aug 2018 09:42:08 -0600 From: Warner Losh <imp@bsdimp.com> To: Ian Lepore <ian@freebsd.org> Cc: Warner Losh <imp@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r337750 - head/share/man/man4 Message-ID: <CANCZdfqHWSshdfp7LYpuJzNuee3crbsE6AkUWyFtOj5TW%2BjH-g@mail.gmail.com> In-Reply-To: <1534255137.31375.121.camel@freebsd.org> References: <201808141352.w7EDqA6F001954@repo.freebsd.org> <1534255137.31375.121.camel@freebsd.org>
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On Tue, Aug 14, 2018 at 7:58 AM, Ian Lepore <ian@freebsd.org> wrote: > On Tue, 2018-08-14 at 13:52 +0000, Warner Losh wrote: > > Author: imp > > Date: Tue Aug 14 13:52:10 2018 > > New Revision: 337750 > > URL: https://svnweb.freebsd.org/changeset/base/337750 > > > > Log: > > Add good description of init and lock devices from sio to uart. > > > > Modified: > > head/share/man/man4/uart.4 > > > > Modified: head/share/man/man4/uart.4 > > ===================================================================== > > ========= > > --- head/share/man/man4/uart.4 Tue Aug 14 13:52:08 2018 > > (r337749) > > +++ head/share/man/man4/uart.4 Tue Aug 14 13:52:10 2018 > > (r337750) > > @@ -225,6 +225,52 @@ Generally speaking, a connection to a DB-9 style > > conne > > level signal at up to 12 volts. > > A connection to header pins or an edge-connector on an embedded > > board > > is typically a TTL signal at 3.3 or 5 volts. > > +.Sh Special Devices > > +The > > +.Nm > > +driver also supports an initial-state and a lock-state control > > +device for each of the callin and the callout "data" devices. > > +The termios settings of a data device are copied > > +from those of the corresponding initial-state device > > +on first opens and are not inherited from previous opens. > > +Use > > +.Xr stty 1 > > +in the normal way on the initial-state devices to program > > +initial termios states suitable for your setup. > > +.Pp > > +The lock termios state acts as flags to disable changing > > +the termios state. > > +E.g., to lock a flag variable such as CRTSCTS, use > > +.Em stty crtscts > > +on the lock-state device. > > +Speeds and special characters > > +may be locked by setting the corresponding value in the lock-state > > +device to any nonzero value. > > +E.g., to lock a speed to 115200, use > > +.Dq Li stty 115200 > > +on the initial-state device and > > +.Dq Li stty 1 > > +on the lock-state device. > > +.Pp > > +Correct programs talking to correctly wired external devices > > +work with almost arbitrary initial states and almost no locking, > > +but other setups may benefit from changing some of the default > > +initial state and locking the state. > > +In particular, the initial states for non (POSIX) standard flags > > +should be set to suit the devices attached and may need to be > > +locked to prevent buggy programs from changing them. > > +E.g., CRTSCTS should be locked on for devices that support > > +RTS/CTS handshaking at all times and off for devices that do not > > +support it at all. > > +CLOCAL should be locked on for devices that do not support carrier. > > +HUPCL may be locked off if you do not > > +want to hang up for some reason. > > +In general, very bad things happen > > +if something is locked to the wrong state, and things should not > > +be locked for devices that support more than one setting. > > +The CLOCAL flag on callin ports should be locked off for logins > > +to avoid certain security holes, but this needs to be done by > > +getty if the callin port is used for anything else. > > .Sh FILES > > .Bl -tag -width "/dev/ttyu?.init" -compact > > .It Pa /dev/ttyu? > > > > Now they're documented together with a different single driver of many > that supports the feature. This is implemented in the tty layer and > applies to all serial drivers, shouldn't it be documented in tty(4)? Hmmm. You're right. I'd thought only uart supported it, but it looks like you're right it's down a layer. I'll move again and put a xref. Warner
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