tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1# SPDX-License-Identifier: GPL-2.0
2config TTY
3 bool "Enable TTY" if EXPERT
4 default y
5 help
6 Allows you to remove TTY support which can save space, and
7 blocks features that require TTY from inclusion in the kernel.
8 TTY is required for any text terminals or serial port
9 communication. Most users should leave this enabled.
10
11if TTY
12
13config VT
14 bool "Virtual terminal" if EXPERT
15 select INPUT
16 default y if !UML
17 help
18 If you say Y here, you will get support for terminal devices with
19 display and keyboard devices. These are called "virtual" because you
20 can run several virtual terminals (also called virtual consoles) on
21 one physical terminal. This is rather useful, for example one
22 virtual terminal can collect system messages and warnings, another
23 one can be used for a text-mode user session, and a third could run
24 an X session, all in parallel. Switching between virtual terminals
25 is done with certain key combinations, usually Alt-<function key>.
26
27 The setterm command ("man setterm") can be used to change the
28 properties (such as colors or beeping) of a virtual terminal. The
29 man page console_codes(4) ("man console_codes") contains the special
30 character sequences that can be used to change those properties
31 directly. The fonts used on virtual terminals can be changed with
32 the setfont ("man setfont") command and the key bindings are defined
33 with the loadkeys ("man loadkeys") command.
34
35 You need at least one virtual terminal device in order to make use
36 of your keyboard and monitor. Therefore, only people configuring an
37 embedded system would want to say N here in order to save some
38 memory; the only way to log into such a system is then via a serial
39 or network connection.
40
41 If unsure, say Y, or else you won't be able to do much with your new
42 shiny Linux system :-)
43
44config CONSOLE_TRANSLATIONS
45 depends on VT
46 default y
47 bool "Enable character translations in console" if EXPERT
48 help
49 This enables support for font mapping and Unicode translation
50 on virtual consoles.
51
52config VT_CONSOLE
53 bool "Support for console on virtual terminal" if EXPERT
54 depends on VT
55 default y
56 help
57 The system console is the device which receives all kernel messages
58 and warnings and which allows logins in single user mode. If you
59 answer Y here, a virtual terminal (the device used to interact with
60 a physical terminal) can be used as system console. This is the most
61 common mode of operations, so you should say Y here unless you want
62 the kernel messages be output only to a serial port (in which case
63 you should say Y to "Console on serial port", below).
64
65 If you do say Y here, by default the currently visible virtual
66 terminal (/dev/tty0) will be used as system console. You can change
67 that with a kernel command line option such as "console=tty3" which
68 would use the third virtual terminal as system console. (Try "man
69 bootparam" or see the documentation of your boot loader (lilo or
70 loadlin) about how to pass options to the kernel at boot time.)
71
72 If unsure, say Y.
73
74config VT_CONSOLE_SLEEP
75 def_bool y
76 depends on VT_CONSOLE && PM_SLEEP
77
78config HW_CONSOLE
79 bool
80 depends on VT
81 default y
82
83config VT_HW_CONSOLE_BINDING
84 bool "Support for binding and unbinding console drivers"
85 depends on HW_CONSOLE
86 help
87 The virtual terminal is the device that interacts with the physical
88 terminal through console drivers. On these systems, at least one
89 console driver is loaded. In other configurations, additional console
90 drivers may be enabled, such as the framebuffer console. If more than
91 1 console driver is enabled, setting this to 'y' will allow you to
92 select the console driver that will serve as the backend for the
93 virtual terminals.
94
95 See <file:Documentation/driver-api/console.rst> for more
96 information. For framebuffer console users, please refer to
97 <file:Documentation/fb/fbcon.rst>.
98
99config UNIX98_PTYS
100 bool "Unix98 PTY support" if EXPERT
101 default y
102 help
103 A pseudo terminal (PTY) is a software device consisting of two
104 halves: a master and a slave. The slave device behaves identical to
105 a physical terminal; the master device is used by a process to
106 read data from and write data to the slave, thereby emulating a
107 terminal. Typical programs for the master side are telnet servers
108 and xterms.
109
110 Linux has traditionally used the BSD-like names /dev/ptyxx for
111 masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
112 has a number of problems. The GNU C library glibc 2.1 and later,
113 however, supports the Unix98 naming standard: in order to acquire a
114 pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
115 terminal is then made available to the process and the pseudo
116 terminal slave can be accessed as /dev/pts/<number>. What was
117 traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
118
119 All modern Linux systems use the Unix98 ptys. Say Y unless
120 you're on an embedded system and want to conserve memory.
121
122config LEGACY_PTYS
123 bool "Legacy (BSD) PTY support"
124 default y
125 help
126 A pseudo terminal (PTY) is a software device consisting of two
127 halves: a master and a slave. The slave device behaves identical to
128 a physical terminal; the master device is used by a process to
129 read data from and write data to the slave, thereby emulating a
130 terminal. Typical programs for the master side are telnet servers
131 and xterms.
132
133 Linux has traditionally used the BSD-like names /dev/ptyxx
134 for masters and /dev/ttyxx for slaves of pseudo
135 terminals. This scheme has a number of problems, including
136 security. This option enables these legacy devices; on most
137 systems, it is safe to say N.
138
139config LEGACY_PTY_COUNT
140 int "Maximum number of legacy PTY in use"
141 depends on LEGACY_PTYS
142 range 0 256
143 default "256"
144 help
145 The maximum number of legacy PTYs that can be used at any one time.
146 The default is 256, and should be more than enough. Embedded
147 systems may want to reduce this to save memory.
148
149 When not in use, each legacy PTY occupies 12 bytes on 32-bit
150 architectures and 24 bytes on 64-bit architectures.
151
152config LEGACY_TIOCSTI
153 bool "Allow legacy TIOCSTI usage"
154 default y
155 help
156 Historically the kernel has allowed TIOCSTI, which will push
157 characters into a controlling TTY. This continues to be used
158 as a malicious privilege escalation mechanism, and provides no
159 meaningful real-world utility any more. Its use is considered
160 a dangerous legacy operation, and can be disabled on most
161 systems.
162
163 Say Y here only if you have confirmed that your system's
164 userspace depends on this functionality to continue operating
165 normally.
166
167 Processes which run with CAP_SYS_ADMIN, such as BRLTTY, can
168 use TIOCSTI even when this is set to N.
169
170 This functionality can be changed at runtime with the
171 dev.tty.legacy_tiocsti sysctl. This configuration option sets
172 the default value of the sysctl.
173
174config LDISC_AUTOLOAD
175 bool "Automatically load TTY Line Disciplines"
176 default y
177 help
178 Historically the kernel has always automatically loaded any
179 line discipline that is in a kernel module when a user asks
180 for it to be loaded with the TIOCSETD ioctl, or through other
181 means. This is not always the best thing to do on systems
182 where you know you will not be using some of the more
183 "ancient" line disciplines, so prevent the kernel from doing
184 this unless the request is coming from a process with the
185 CAP_SYS_MODULE permissions.
186
187 Say 'Y' here if you trust your userspace users to do the right
188 thing, or if you have only provided the line disciplines that
189 you know you will be using, or if you wish to continue to use
190 the traditional method of on-demand loading of these modules
191 by any user.
192
193 This functionality can be changed at runtime with the
194 dev.tty.ldisc_autoload sysctl, this configuration option will
195 only set the default value of this functionality.
196
197source "drivers/tty/serial/Kconfig"
198
199config SERIAL_NONSTANDARD
200 bool "Non-standard serial port support"
201 depends on HAS_IOMEM
202 help
203 Say Y here if you have any non-standard serial boards -- boards
204 which aren't supported using the standard "dumb" serial driver.
205 This includes intelligent serial boards such as
206 Digiboards, etc. These are usually used for systems that need many
207 serial ports because they serve many terminals or dial-in
208 connections.
209
210 Note that the answer to this question won't directly affect the
211 kernel: saying N will just cause the configurator to skip all
212 the questions about non-standard serial boards.
213
214 Most people can say N here.
215
216config MOXA_INTELLIO
217 tristate "Moxa Intellio support"
218 depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
219 select FW_LOADER
220 help
221 Say Y here if you have a Moxa Intellio multiport serial card.
222
223 To compile this driver as a module, choose M here: the
224 module will be called moxa.
225
226config MOXA_SMARTIO
227 tristate "Moxa SmartIO support v. 2.0"
228 depends on SERIAL_NONSTANDARD && PCI
229 help
230 Say Y here if you have a Moxa SmartIO multiport serial card and/or
231 want to help develop a new version of this driver.
232
233 This is upgraded (1.9.1) driver from original Moxa drivers with
234 changes finally resulting in PCI probing.
235
236 This driver can also be built as a module. The module will be called
237 mxser. If you want to do that, say M here.
238
239config SYNCLINK_GT
240 tristate "SyncLink GT/AC support"
241 depends on SERIAL_NONSTANDARD && PCI
242 help
243 Support for SyncLink GT and SyncLink AC families of
244 synchronous and asynchronous serial adapters
245 manufactured by Microgate Systems, Ltd. (www.microgate.com)
246
247config N_HDLC
248 tristate "HDLC line discipline support"
249 depends on SERIAL_NONSTANDARD
250 help
251 Allows synchronous HDLC communications with tty device drivers that
252 support synchronous HDLC such as the Microgate SyncLink adapter.
253
254 This driver can be built as a module ( = code which can be
255 inserted in and removed from the running kernel whenever you want).
256 The module will be called n_hdlc. If you want to do that, say M
257 here.
258
259config PPC_EPAPR_HV_BYTECHAN
260 bool "ePAPR hypervisor byte channel driver"
261 depends on PPC
262 select EPAPR_PARAVIRT
263 help
264 This driver creates /dev entries for each ePAPR hypervisor byte
265 channel, thereby allowing applications to communicate with byte
266 channels as if they were serial ports.
267
268config PPC_EARLY_DEBUG_EHV_BC
269 bool "Early console (udbg) support for ePAPR hypervisors"
270 depends on PPC_EPAPR_HV_BYTECHAN=y
271 help
272 Select this option to enable early console (a.k.a. "udbg") support
273 via an ePAPR byte channel. You also need to choose the byte channel
274 handle below.
275
276config PPC_EARLY_DEBUG_EHV_BC_HANDLE
277 int "Byte channel handle for early console (udbg)"
278 depends on PPC_EARLY_DEBUG_EHV_BC
279 default 0
280 help
281 If you want early console (udbg) output through a byte channel,
282 specify the handle of the byte channel to use.
283
284 For this to work, the byte channel driver must be compiled
285 in-kernel, not as a module.
286
287 Note that only one early console driver can be enabled, so don't
288 enable any others if you enable this one.
289
290 If the number you specify is not a valid byte channel handle, then
291 there simply will be no early console output. This is true also
292 if you don't boot under a hypervisor at all.
293
294config GOLDFISH_TTY
295 tristate "Goldfish TTY Driver"
296 depends on GOLDFISH
297 select SERIAL_CORE
298 select SERIAL_CORE_CONSOLE
299 help
300 Console and system TTY driver for the Goldfish virtual platform.
301
302config GOLDFISH_TTY_EARLY_CONSOLE
303 bool
304 default y if GOLDFISH_TTY=y
305 select SERIAL_EARLYCON
306
307config IPWIRELESS
308 tristate "IPWireless 3G UMTS PCMCIA card support"
309 depends on PCMCIA && NETDEVICES
310 select PPP
311 help
312 This is a driver for 3G UMTS PCMCIA card from IPWireless company. In
313 some countries (for example Czech Republic, T-Mobile ISP) this card
314 is shipped for service called UMTS 4G.
315
316config N_GSM
317 tristate "GSM MUX line discipline support (EXPERIMENTAL)"
318 depends on NET
319 help
320 This line discipline provides support for the GSM MUX protocol and
321 presents the mux as a set of 61 individual tty devices.
322
323config NOZOMI
324 tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
325 depends on PCI
326 help
327 If you have a HSDPA driver Broadband Wireless Data Card -
328 Globe Trotter PCMCIA card, say Y here.
329
330 To compile this driver as a module, choose M here, the module
331 will be called nozomi.
332
333config MIPS_EJTAG_FDC_TTY
334 bool "MIPS EJTAG Fast Debug Channel TTY"
335 depends on MIPS_CDMM
336 help
337 This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
338 if they are present. This can be useful when working with an EJTAG
339 probe which supports it, to get console output and a login prompt via
340 EJTAG without needing to connect a serial cable.
341
342 TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
343 CPU3).
344
345 The console can be enabled with console=fdc1 (for FDC channel 1 on all
346 CPUs). Do not use the console unless there is a debug probe attached
347 to drain the FDC TX FIFO.
348
349 If unsure, say N.
350
351config MIPS_EJTAG_FDC_EARLYCON
352 bool "Early FDC console"
353 depends on MIPS_EJTAG_FDC_TTY
354 help
355 This registers a console on FDC channel 1 very early during boot (from
356 MIPS arch code). This is useful for bring-up and debugging early boot
357 issues.
358
359 Do not enable unless there is a debug probe attached to drain the FDC
360 TX FIFO.
361
362 If unsure, say N.
363
364config MIPS_EJTAG_FDC_KGDB
365 bool "Use KGDB over an FDC channel"
366 depends on MIPS_EJTAG_FDC_TTY && KGDB
367 default y
368 help
369 This enables the use of KGDB over an FDC channel, allowing KGDB to be
370 used remotely or when a serial port isn't available.
371
372config MIPS_EJTAG_FDC_KGDB_CHAN
373 int "KGDB FDC channel"
374 depends on MIPS_EJTAG_FDC_KGDB
375 range 2 15
376 default 3
377 help
378 FDC channel number to use for KGDB.
379
380config NULL_TTY
381 tristate "NULL TTY driver"
382 help
383 Say Y here if you want a NULL TTY which simply discards messages.
384
385 This is useful to allow userspace applications which expect a console
386 device to work without modifications even when no console is
387 available or desired.
388
389 In order to use this driver, you should redirect the console to this
390 TTY, or boot the kernel with console=ttynull.
391
392 If unsure, say N.
393
394config VCC
395 tristate "Sun Virtual Console Concentrator"
396 depends on SUN_LDOMS
397 help
398 Support for Sun logical domain consoles.
399
400source "drivers/tty/hvc/Kconfig"
401
402config RPMSG_TTY
403 tristate "RPMSG tty driver"
404 depends on RPMSG
405 help
406 Say y here to export rpmsg endpoints as tty devices, usually found
407 in /dev/ttyRPMSGx.
408 This makes it possible for user-space programs to send and receive
409 rpmsg messages as a standard tty protocol.
410
411 To compile this driver as a module, choose M here: the module will be
412 called rpmsg_tty.
413
414endif # TTY
415
416source "drivers/tty/serdev/Kconfig"