Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
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 VT_HW_CONSOLE_BINDING
79 bool "Support for binding and unbinding console drivers"
80 depends on VT
81 help
82 The virtual terminal is the device that interacts with the physical
83 terminal through console drivers. On these systems, at least one
84 console driver is loaded. In other configurations, additional console
85 drivers may be enabled, such as the framebuffer console. If more than
86 1 console driver is enabled, setting this to 'y' will allow you to
87 select the console driver that will serve as the backend for the
88 virtual terminals.
89
90 See <file:Documentation/driver-api/console.rst> for more
91 information. For framebuffer console users, please refer to
92 <file:Documentation/fb/fbcon.rst>.
93
94config UNIX98_PTYS
95 bool "Unix98 PTY support" if EXPERT
96 default y
97 help
98 A pseudo terminal (PTY) is a software device consisting of two
99 halves: a master and a slave. The slave device behaves identical to
100 a physical terminal; the master device is used by a process to
101 read data from and write data to the slave, thereby emulating a
102 terminal. Typical programs for the master side are telnet servers
103 and xterms.
104
105 Linux has traditionally used the BSD-like names /dev/ptyxx for
106 masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
107 has a number of problems. The GNU C library glibc 2.1 and later,
108 however, supports the Unix98 naming standard: in order to acquire a
109 pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
110 terminal is then made available to the process and the pseudo
111 terminal slave can be accessed as /dev/pts/<number>. What was
112 traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
113
114 All modern Linux systems use the Unix98 ptys. Say Y unless
115 you're on an embedded system and want to conserve memory.
116
117config LEGACY_PTYS
118 bool "Legacy (BSD) PTY support"
119 default y
120 help
121 A pseudo terminal (PTY) is a software device consisting of two
122 halves: a master and a slave. The slave device behaves identical to
123 a physical terminal; the master device is used by a process to
124 read data from and write data to the slave, thereby emulating a
125 terminal. Typical programs for the master side are telnet servers
126 and xterms.
127
128 Linux has traditionally used the BSD-like names /dev/ptyxx
129 for masters and /dev/ttyxx for slaves of pseudo
130 terminals. This scheme has a number of problems, including
131 security. This option enables these legacy devices; on most
132 systems, it is safe to say N.
133
134config LEGACY_PTY_COUNT
135 int "Maximum number of legacy PTY in use"
136 depends on LEGACY_PTYS
137 range 0 256
138 default "256"
139 help
140 The maximum number of legacy PTYs that can be used at any one time.
141 The default is 256, and should be more than enough. Embedded
142 systems may want to reduce this to save memory.
143
144 When not in use, each legacy PTY occupies 12 bytes on 32-bit
145 architectures and 24 bytes on 64-bit architectures.
146
147config LEGACY_TIOCSTI
148 bool "Allow legacy TIOCSTI usage"
149 default y
150 help
151 Historically the kernel has allowed TIOCSTI, which will push
152 characters into a controlling TTY. This continues to be used
153 as a malicious privilege escalation mechanism, and provides no
154 meaningful real-world utility any more. Its use is considered
155 a dangerous legacy operation, and can be disabled on most
156 systems.
157
158 Say Y here only if you have confirmed that your system's
159 userspace depends on this functionality to continue operating
160 normally.
161
162 Processes which run with CAP_SYS_ADMIN, such as BRLTTY, can
163 use TIOCSTI even when this is set to N.
164
165 This functionality can be changed at runtime with the
166 dev.tty.legacy_tiocsti sysctl. This configuration option sets
167 the default value of the sysctl.
168
169config LDISC_AUTOLOAD
170 bool "Automatically load TTY Line Disciplines"
171 default y
172 help
173 Historically the kernel has always automatically loaded any
174 line discipline that is in a kernel module when a user asks
175 for it to be loaded with the TIOCSETD ioctl, or through other
176 means. This is not always the best thing to do on systems
177 where you know you will not be using some of the more
178 "ancient" line disciplines, so prevent the kernel from doing
179 this unless the request is coming from a process with the
180 CAP_SYS_MODULE permissions.
181
182 Say 'Y' here if you trust your userspace users to do the right
183 thing, or if you have only provided the line disciplines that
184 you know you will be using, or if you wish to continue to use
185 the traditional method of on-demand loading of these modules
186 by any user.
187
188 This functionality can be changed at runtime with the
189 dev.tty.ldisc_autoload sysctl, this configuration option will
190 only set the default value of this functionality.
191
192source "drivers/tty/serial/Kconfig"
193
194config SERIAL_NONSTANDARD
195 bool "Non-standard serial port support"
196 depends on HAS_IOMEM
197 help
198 Say Y here if you have any non-standard serial boards -- boards
199 which aren't supported using the standard "dumb" serial driver.
200 This includes intelligent serial boards such as
201 Digiboards, etc. These are usually used for systems that need many
202 serial ports because they serve many terminals or dial-in
203 connections.
204
205 Note that the answer to this question won't directly affect the
206 kernel: saying N will just cause the configurator to skip all
207 the questions about non-standard serial boards.
208
209 Most people can say N here.
210
211config MOXA_INTELLIO
212 tristate "Moxa Intellio support"
213 depends on SERIAL_NONSTANDARD && PCI
214 select FW_LOADER
215 help
216 Say Y here if you have a Moxa Intellio multiport serial card.
217
218 To compile this driver as a module, choose M here: the
219 module will be called moxa.
220
221config MOXA_SMARTIO
222 tristate "Moxa SmartIO support v. 2.0"
223 depends on SERIAL_NONSTANDARD && PCI && HAS_IOPORT
224 help
225 Say Y here if you have a Moxa SmartIO multiport serial card and/or
226 want to help develop a new version of this driver.
227
228 This is upgraded (1.9.1) driver from original Moxa drivers with
229 changes finally resulting in PCI probing.
230
231 This driver can also be built as a module. The module will be called
232 mxser. If you want to do that, say M here.
233
234config SYNCLINK_GT
235 tristate "SyncLink GT/AC support"
236 depends on SERIAL_NONSTANDARD && PCI
237 depends on BROKEN
238 help
239 Support for SyncLink GT and SyncLink AC families of
240 synchronous and asynchronous serial adapters
241 manufactured by Microgate Systems, Ltd. (www.microgate.com)
242
243config N_HDLC
244 tristate "HDLC line discipline support"
245 depends on SERIAL_NONSTANDARD
246 help
247 Allows synchronous HDLC communications with tty device drivers that
248 support synchronous HDLC such as the Microgate SyncLink adapter.
249
250 This driver can be built as a module ( = code which can be
251 inserted in and removed from the running kernel whenever you want).
252 The module will be called n_hdlc. If you want to do that, say M
253 here.
254
255config PPC_EPAPR_HV_BYTECHAN
256 bool "ePAPR hypervisor byte channel driver"
257 depends on PPC
258 select EPAPR_PARAVIRT
259 help
260 This driver creates /dev entries for each ePAPR hypervisor byte
261 channel, thereby allowing applications to communicate with byte
262 channels as if they were serial ports.
263
264config PPC_EARLY_DEBUG_EHV_BC
265 bool "Early console (udbg) support for ePAPR hypervisors"
266 depends on PPC_EPAPR_HV_BYTECHAN=y
267 help
268 Select this option to enable early console (a.k.a. "udbg") support
269 via an ePAPR byte channel. You also need to choose the byte channel
270 handle below.
271
272config PPC_EARLY_DEBUG_EHV_BC_HANDLE
273 int "Byte channel handle for early console (udbg)"
274 depends on PPC_EARLY_DEBUG_EHV_BC
275 default 0
276 help
277 If you want early console (udbg) output through a byte channel,
278 specify the handle of the byte channel to use.
279
280 For this to work, the byte channel driver must be compiled
281 in-kernel, not as a module.
282
283 Note that only one early console driver can be enabled, so don't
284 enable any others if you enable this one.
285
286 If the number you specify is not a valid byte channel handle, then
287 there simply will be no early console output. This is true also
288 if you don't boot under a hypervisor at all.
289
290config GOLDFISH_TTY
291 tristate "Goldfish TTY Driver"
292 depends on GOLDFISH
293 select SERIAL_CORE
294 select SERIAL_CORE_CONSOLE
295 help
296 Console and system TTY driver for the Goldfish virtual platform.
297
298config GOLDFISH_TTY_EARLY_CONSOLE
299 bool
300 default y if GOLDFISH_TTY=y
301 select SERIAL_EARLYCON
302
303config IPWIRELESS
304 tristate "IPWireless 3G UMTS PCMCIA card support"
305 depends on PCMCIA && NETDEVICES && HAS_IOPORT
306 select PPP
307 help
308 This is a driver for 3G UMTS PCMCIA card from IPWireless company. In
309 some countries (for example Czech Republic, T-Mobile ISP) this card
310 is shipped for service called UMTS 4G.
311
312config N_GSM
313 tristate "GSM MUX line discipline support (EXPERIMENTAL)"
314 depends on NET
315 help
316 This line discipline provides support for the GSM MUX protocol and
317 presents the mux as a set of 61 individual tty devices.
318
319config NOZOMI
320 tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
321 depends on PCI
322 help
323 If you have a HSDPA driver Broadband Wireless Data Card -
324 Globe Trotter PCMCIA card, say Y here.
325
326 To compile this driver as a module, choose M here, the module
327 will be called nozomi.
328
329config MIPS_EJTAG_FDC_TTY
330 bool "MIPS EJTAG Fast Debug Channel TTY"
331 depends on MIPS_CDMM
332 help
333 This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
334 if they are present. This can be useful when working with an EJTAG
335 probe which supports it, to get console output and a login prompt via
336 EJTAG without needing to connect a serial cable.
337
338 TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
339 CPU3).
340
341 The console can be enabled with console=fdc1 (for FDC channel 1 on all
342 CPUs). Do not use the console unless there is a debug probe attached
343 to drain the FDC TX FIFO.
344
345 If unsure, say N.
346
347config MIPS_EJTAG_FDC_EARLYCON
348 bool "Early FDC console"
349 depends on MIPS_EJTAG_FDC_TTY
350 help
351 This registers a console on FDC channel 1 very early during boot (from
352 MIPS arch code). This is useful for bring-up and debugging early boot
353 issues.
354
355 Do not enable unless there is a debug probe attached to drain the FDC
356 TX FIFO.
357
358 If unsure, say N.
359
360config MIPS_EJTAG_FDC_KGDB
361 bool "Use KGDB over an FDC channel"
362 depends on MIPS_EJTAG_FDC_TTY && KGDB
363 default y
364 help
365 This enables the use of KGDB over an FDC channel, allowing KGDB to be
366 used remotely or when a serial port isn't available.
367
368config MIPS_EJTAG_FDC_KGDB_CHAN
369 int "KGDB FDC channel"
370 depends on MIPS_EJTAG_FDC_KGDB
371 range 2 15
372 default 3
373 help
374 FDC channel number to use for KGDB.
375
376config NULL_TTY
377 tristate "NULL TTY driver"
378 help
379 Say Y here if you want a NULL TTY which simply discards messages.
380
381 This is useful to allow userspace applications which expect a console
382 device to work without modifications even when no console is
383 available or desired.
384
385 In order to use this driver, you should redirect the console to this
386 TTY, boot the kernel with console=ttynull, or enable
387 NULL_TTY_DEFAULT_CONSOLE.
388
389 If unsure, say N.
390
391config NULL_TTY_DEFAULT_CONSOLE
392 bool "Support for console on ttynull"
393 depends on NULL_TTY=y && !VT_CONSOLE
394 help
395 Say Y here if you want the NULL TTY to be used as a /dev/console
396 device by default.
397
398 For example, it might be useful to prevent a VT-less kernel from
399 writing the system log to a random device connected to the serial
400 port.
401
402 Another console driver still might get preferred via the command
403 line, SPCR, or the device tree.
404
405 If unsure, say N.
406
407config VCC
408 tristate "Sun Virtual Console Concentrator"
409 depends on SUN_LDOMS
410 help
411 Support for Sun logical domain consoles.
412
413source "drivers/tty/hvc/Kconfig"
414
415config RPMSG_TTY
416 tristate "RPMSG tty driver"
417 depends on RPMSG
418 help
419 Say y here to export rpmsg endpoints as tty devices, usually found
420 in /dev/ttyRPMSGx.
421 This makes it possible for user-space programs to send and receive
422 rpmsg messages as a standard tty protocol.
423
424 To compile this driver as a module, choose M here: the module will be
425 called rpmsg_tty.
426
427endif # TTY
428
429source "drivers/tty/serdev/Kconfig"