1 # SPDX-License-Identifier: GPL-2.0
3 bool "Enable TTY" if EXPERT
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.
14 bool "Virtual terminal" if EXPERT
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>.
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.
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.
41 If unsure, say Y, or else you won't be able to do much with your new
42 shiny Linux system :-)
44 config CONSOLE_TRANSLATIONS
47 bool "Enable character translations in console" if EXPERT
49 This enables support for font mapping and Unicode translation
53 bool "Support for console on virtual terminal" if EXPERT
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).
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.)
74 config VT_CONSOLE_SLEEP
76 depends on VT_CONSOLE && PM_SLEEP
83 config VT_HW_CONSOLE_BINDING
84 bool "Support for binding and unbinding console drivers"
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
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>.
100 bool "Unix98 PTY support" if EXPERT
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
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.
119 All modern Linux systems use the Unix98 ptys. Say Y unless
120 you're on an embedded system and want to conserve memory.
123 bool "Legacy (BSD) PTY support"
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
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.
139 config LEGACY_PTY_COUNT
140 int "Maximum number of legacy PTY in use"
141 depends on LEGACY_PTYS
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.
149 When not in use, each legacy PTY occupies 12 bytes on 32-bit
150 architectures and 24 bytes on 64-bit architectures.
152 config LDISC_AUTOLOAD
153 bool "Automatically load TTY Line Disciplines"
156 Historically the kernel has always automatically loaded any
157 line discipline that is in a kernel module when a user asks
158 for it to be loaded with the TIOCSETD ioctl, or through other
159 means. This is not always the best thing to do on systems
160 where you know you will not be using some of the more
161 "ancient" line disciplines, so prevent the kernel from doing
162 this unless the request is coming from a process with the
163 CAP_SYS_MODULE permissions.
165 Say 'Y' here if you trust your userspace users to do the right
166 thing, or if you have only provided the line disciplines that
167 you know you will be using, or if you wish to continue to use
168 the traditional method of on-demand loading of these modules
171 This functionality can be changed at runtime with the
172 dev.tty.ldisc_autoload sysctl, this configuration option will
173 only set the default value of this functionality.
175 source "drivers/tty/serial/Kconfig"
177 config SERIAL_NONSTANDARD
178 bool "Non-standard serial port support"
181 Say Y here if you have any non-standard serial boards -- boards
182 which aren't supported using the standard "dumb" serial driver.
183 This includes intelligent serial boards such as
184 Digiboards, etc. These are usually used for systems that need many
185 serial ports because they serve many terminals or dial-in
188 Note that the answer to this question won't directly affect the
189 kernel: saying N will just cause the configurator to skip all
190 the questions about non-standard serial boards.
192 Most people can say N here.
195 tristate "Moxa Intellio support"
196 depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
199 Say Y here if you have a Moxa Intellio multiport serial card.
201 To compile this driver as a module, choose M here: the
202 module will be called moxa.
205 tristate "Moxa SmartIO support v. 2.0"
206 depends on SERIAL_NONSTANDARD && PCI
208 Say Y here if you have a Moxa SmartIO multiport serial card and/or
209 want to help develop a new version of this driver.
211 This is upgraded (1.9.1) driver from original Moxa drivers with
212 changes finally resulting in PCI probing.
214 This driver can also be built as a module. The module will be called
215 mxser. If you want to do that, say M here.
218 tristate "SyncLink GT/AC support"
219 depends on SERIAL_NONSTANDARD && PCI
221 Support for SyncLink GT and SyncLink AC families of
222 synchronous and asynchronous serial adapters
223 manufactured by Microgate Systems, Ltd. (www.microgate.com)
226 tristate "HDLC line discipline support"
227 depends on SERIAL_NONSTANDARD
229 Allows synchronous HDLC communications with tty device drivers that
230 support synchronous HDLC such as the Microgate SyncLink adapter.
232 This driver can be built as a module ( = code which can be
233 inserted in and removed from the running kernel whenever you want).
234 The module will be called n_hdlc. If you want to do that, say M
237 config PPC_EPAPR_HV_BYTECHAN
238 bool "ePAPR hypervisor byte channel driver"
240 select EPAPR_PARAVIRT
242 This driver creates /dev entries for each ePAPR hypervisor byte
243 channel, thereby allowing applications to communicate with byte
244 channels as if they were serial ports.
246 config PPC_EARLY_DEBUG_EHV_BC
247 bool "Early console (udbg) support for ePAPR hypervisors"
248 depends on PPC_EPAPR_HV_BYTECHAN=y
250 Select this option to enable early console (a.k.a. "udbg") support
251 via an ePAPR byte channel. You also need to choose the byte channel
254 config PPC_EARLY_DEBUG_EHV_BC_HANDLE
255 int "Byte channel handle for early console (udbg)"
256 depends on PPC_EARLY_DEBUG_EHV_BC
259 If you want early console (udbg) output through a byte channel,
260 specify the handle of the byte channel to use.
262 For this to work, the byte channel driver must be compiled
263 in-kernel, not as a module.
265 Note that only one early console driver can be enabled, so don't
266 enable any others if you enable this one.
268 If the number you specify is not a valid byte channel handle, then
269 there simply will be no early console output. This is true also
270 if you don't boot under a hypervisor at all.
273 tristate "Goldfish TTY Driver"
276 select SERIAL_CORE_CONSOLE
278 Console and system TTY driver for the Goldfish virtual platform.
280 config GOLDFISH_TTY_EARLY_CONSOLE
282 default y if GOLDFISH_TTY=y
283 select SERIAL_EARLYCON
286 tristate "GSM MUX line discipline support (EXPERIMENTAL)"
289 This line discipline provides support for the GSM MUX protocol and
290 presents the mux as a set of 61 individual tty devices.
293 tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
296 If you have a HSDPA driver Broadband Wireless Data Card -
297 Globe Trotter PCMCIA card, say Y here.
299 To compile this driver as a module, choose M here, the module
300 will be called nozomi.
302 config MIPS_EJTAG_FDC_TTY
303 bool "MIPS EJTAG Fast Debug Channel TTY"
306 This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
307 if they are present. This can be useful when working with an EJTAG
308 probe which supports it, to get console output and a login prompt via
309 EJTAG without needing to connect a serial cable.
311 TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
314 The console can be enabled with console=fdc1 (for FDC channel 1 on all
315 CPUs). Do not use the console unless there is a debug probe attached
316 to drain the FDC TX FIFO.
320 config MIPS_EJTAG_FDC_EARLYCON
321 bool "Early FDC console"
322 depends on MIPS_EJTAG_FDC_TTY
324 This registers a console on FDC channel 1 very early during boot (from
325 MIPS arch code). This is useful for bring-up and debugging early boot
328 Do not enable unless there is a debug probe attached to drain the FDC
333 config MIPS_EJTAG_FDC_KGDB
334 bool "Use KGDB over an FDC channel"
335 depends on MIPS_EJTAG_FDC_TTY && KGDB
338 This enables the use of KGDB over an FDC channel, allowing KGDB to be
339 used remotely or when a serial port isn't available.
341 config MIPS_EJTAG_FDC_KGDB_CHAN
342 int "KGDB FDC channel"
343 depends on MIPS_EJTAG_FDC_KGDB
347 FDC channel number to use for KGDB.
350 tristate "NULL TTY driver"
352 Say Y here if you want a NULL TTY which simply discards messages.
354 This is useful to allow userspace applications which expect a console
355 device to work without modifications even when no console is
356 available or desired.
358 In order to use this driver, you should redirect the console to this
359 TTY, or boot the kernel with console=ttynull.
364 tristate "Sun Virtual Console Concentrator"
367 Support for Sun logical domain consoles.
369 source "drivers/tty/hvc/Kconfig"
373 source "drivers/tty/serdev/Kconfig"