1su(7D) Devices su(7D)
2
6 su - asynchronous serial port driver
7
9 #include <fcntl.h>
10 #include <sys/termios.h>
11 open("/dev/tty[a-z]", _mode);
12 open("/dev/term[a-z]", _mode);
13 open("/dev/cua[a-z]", _mode);
14
17 The su module is a loadable STREAMS driver that provides basic support
18 for standard UARTS that use Intel-8250, National Semiconduc‐
19 tor-16450/16550 hardware and Southbridge 1535D (16550 compatable) Super
20 I/O hardware. The module also provides keyboard and mouse I/O support
21 for Sun machines using those same Intel, National Semiconductor and
22 Southbridge chipsets. The su driver provides basic asynchronous commu‐
23 nication support for serial ports. Both the serial devices and key‐
24 board/mouse devices will have streams built with appropriate modules
25 pushed atop the su driver by means of either the autopush(1M) or
26 dacf.conf(4) facilities, depending on the OS revision and architecture
27 in use.
28 The su module supports those termio(7I) device control functions speci‐
31 fied by flags in the c_cflag word of the termios structure, and by the
32 IGNBRK, IGNPAR, PARMRK, or INPCK flags in the c_iflag word of the
33 termios structure. All other termio(7I) functions must be performed by
34 STREAMS modules pushed atop the driver. When a device is opened, the
35 ldterm(7M) and ttcompat(7M) STREAMS modules are automatically pushed on
36 top of the stream, providing the standard termio(7I) interface.
37 The character-special devices /dev/ttya and /dev/ttyb are used to
40 access the two standard serial ports. The su module supports up to ten
41 serial ports, including the standard ports. The tty[a-z] devices have
42 minor device numbers in the range 00-03, and may be assigned names of
43 the form /dev/ttyd_n_, where _n_ denotes the line to be accessed.
44 These device names are typically used to provide a logical access point
45 for a _dial-in_ line that is used with a modem.
46 To allow a single tty line to be connected to a modem and used for
49 incoming and outgoing calls, a special feature is available that is
50 controlled by the minor device number. By accessing character-special
51 devices with names of the form /dev/cua_n, it is possible to open a
52 port without the Carrier Detect signal being asserted, either through
53 hardware or an equivalent software mechanism. These devices are com‐
54 monly known as _dial-out_ lines.
55
57 Once a /dev/cua_n_ line is opened, the corresponding tty, or ttyd line
58 cannot be opened until the /dev/cua_n_ line is closed. A blocking open
59 will wait until the /dev/cua_n_ line is closed (which will drop Data
60 Terminal Ready, after which Carrier Detect will usually drop as well)
61 and carrier is detected again. A non-blocking open will return an
62 error. If the /dev/ttyd_n_ line has been opened successfully (usually
63 only when carrier is recognized on the modem), the corresponding
64 /dev/cua_n_ line cannot be opened. This allows a modem to be attached
65 to a device, (for example, /dev/ttyd0, which is renamed from
66 /dev/tty00) and used for dial-in (by enabling the line for login in
67 /etc/inittab) or dial-out (by tip(1) or uucp(1C)) as /dev/cua0 when no
68 one is logged in on the line.
69
71 The standard set of termio ioctl() calls are supported by su.
72 Breaks can be generated by the TCSBRK, TIOCSBRK, and TIOCCBRK ioctl()
75 calls.
76 The input and output line speeds may be set to any of the following
79 baud rates: 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800,
80 2400, 4800, 9600, 19200, 38400, 57600 or 115200. The speeds cannot be
81 set independently; for example, when the output speed is set, the input
82 speed is automatically set to the same speed.
83 When the su module is used to service the serial console port, it sup‐
86 ports a BREAK condition that allows the system to enter the debugger or
87 the monitor. The BREAK condition is generated by hardware and it is
88 usually enabled by default.
89 A BREAK condition originating from erroneous electrical signals cannot
92 be distinguished from one deliberately sent by remote DCE. The Alter‐
93 nate Break sequence can be used as a remedy against this. Due to a risk
94 of incorrect sequence interpretation, SLIP and certain other binary
95 protocols should not be run over the serial console port when Alternate
96 Break sequence is in effect. Although PPP is a binary protocol, it is
97 able to avoid these sequences using the ACCM feature in RFC 1662. For
98 Solaris PPP 4.0, you do this by adding the following line to the
99 /etc/ppp/options file (or other configuration files used for the con‐
100 nection; see pppd(1M) for details):
101 asyncmap 0x00002000
103 By default, the Alternate Break sequence is a three character sequence:
107 carriage return, tilde and control-B (CR ~ CTRL-B), but may be changed
108 by the driver. For more information on breaking (entering the debugger
109 or monitor), see kbd(1) and kb(7M).
110
112 An open() will fail under the following conditions:
113 ENXIO The unit being opened does not exist.
115 EBUSY The dial-out device is being opened while the dial-in device
118 is already open, or the dial-in device is being opened with a
119 no-delay open and the dial-out device is already open.
120 EBUSY The unit has been marked as exclusive-use by another process
123 with a TIOCEXCL ioctl() call.
124
127 /dev/cua/[a-z] dial-out tty lines
128 /dev/term/[a-z] dial-in tty lines
131 /dev/tty[a-z] binary compatibility package device names
134
137 See attributes(5) for descriptions of the following attributes:
138 ┌─────────────────────────────┬─────────────────────────────┐
143 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
144 ├─────────────────────────────┼─────────────────────────────┤
145 │Architecture │ SPARC │
146 └─────────────────────────────┴─────────────────────────────┘
147
149 strconf(1), kbd(1), tip(1),uucp(1C), autopush(1M), kstat(1M), pppd(1M),
150 ioctl(2), open(2), termios(3C), dacf.conf(4), attributes(5), kb(7M),
151 ldterm(7M), ttcompat(7M), termio(7I)
152
154 The su driver keeps track of various warning and error conditions using
155 kstat counters. The output of the kstat su command provides kstat coun‐
156 ters. The counters and their meaning follow:
157 silo overflow The internal chip FIFO received more data than
159 it could handle. This indicates that the
160 Solaris operating environment was not servicing
161 data interrupts fast enough possibly due to a
162 system with too many interrupts or a data line
163 with a data rate that is too high.
164 ring buffer overflow The su module was unable to store data it
167 removed from the chips internal FIFO into a
168 software buffer. The user process is not read‐
169 ing data fast enough, possibly due to an over‐
170 loaded system. If possible, the application
171 should enable flow control (either CTSRTS or
172 XONXOFF) to allow the driver to backpressure
173 the remote system when the local buffers fill
174 up.
175SunOS 5.11 18 June 2004 su(7D)