Date: Tue, 14 Aug 2018 07:58:57 -0600 From: Ian Lepore <ian@freebsd.org> To: Warner Losh <imp@FreeBSD.org>, 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: <1534255137.31375.121.camel@freebsd.org> In-Reply-To: <201808141352.w7EDqA6F001954@repo.freebsd.org> References: <201808141352.w7EDqA6F001954@repo.freebsd.org>
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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)? -- Ian
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