0001 # SPDX-License-Identifier: GPL-2.0
0002 config TTY
0003 bool "Enable TTY" if EXPERT
0004 default y
0005 help
0006 Allows you to remove TTY support which can save space, and
0007 blocks features that require TTY from inclusion in the kernel.
0008 TTY is required for any text terminals or serial port
0009 communication. Most users should leave this enabled.
0010
0011 if TTY
0012
0013 config VT
0014 bool "Virtual terminal" if EXPERT
0015 select INPUT
0016 default y if !UML
0017 help
0018 If you say Y here, you will get support for terminal devices with
0019 display and keyboard devices. These are called "virtual" because you
0020 can run several virtual terminals (also called virtual consoles) on
0021 one physical terminal. This is rather useful, for example one
0022 virtual terminal can collect system messages and warnings, another
0023 one can be used for a text-mode user session, and a third could run
0024 an X session, all in parallel. Switching between virtual terminals
0025 is done with certain key combinations, usually Alt-<function key>.
0026
0027 The setterm command ("man setterm") can be used to change the
0028 properties (such as colors or beeping) of a virtual terminal. The
0029 man page console_codes(4) ("man console_codes") contains the special
0030 character sequences that can be used to change those properties
0031 directly. The fonts used on virtual terminals can be changed with
0032 the setfont ("man setfont") command and the key bindings are defined
0033 with the loadkeys ("man loadkeys") command.
0034
0035 You need at least one virtual terminal device in order to make use
0036 of your keyboard and monitor. Therefore, only people configuring an
0037 embedded system would want to say N here in order to save some
0038 memory; the only way to log into such a system is then via a serial
0039 or network connection.
0040
0041 If unsure, say Y, or else you won't be able to do much with your new
0042 shiny Linux system :-)
0043
0044 config CONSOLE_TRANSLATIONS
0045 depends on VT
0046 default y
0047 bool "Enable character translations in console" if EXPERT
0048 help
0049 This enables support for font mapping and Unicode translation
0050 on virtual consoles.
0051
0052 config VT_CONSOLE
0053 bool "Support for console on virtual terminal" if EXPERT
0054 depends on VT
0055 default y
0056 help
0057 The system console is the device which receives all kernel messages
0058 and warnings and which allows logins in single user mode. If you
0059 answer Y here, a virtual terminal (the device used to interact with
0060 a physical terminal) can be used as system console. This is the most
0061 common mode of operations, so you should say Y here unless you want
0062 the kernel messages be output only to a serial port (in which case
0063 you should say Y to "Console on serial port", below).
0064
0065 If you do say Y here, by default the currently visible virtual
0066 terminal (/dev/tty0) will be used as system console. You can change
0067 that with a kernel command line option such as "console=tty3" which
0068 would use the third virtual terminal as system console. (Try "man
0069 bootparam" or see the documentation of your boot loader (lilo or
0070 loadlin) about how to pass options to the kernel at boot time.)
0071
0072 If unsure, say Y.
0073
0074 config VT_CONSOLE_SLEEP
0075 def_bool y
0076 depends on VT_CONSOLE && PM_SLEEP
0077
0078 config HW_CONSOLE
0079 bool
0080 depends on VT
0081 default y
0082
0083 config VT_HW_CONSOLE_BINDING
0084 bool "Support for binding and unbinding console drivers"
0085 depends on HW_CONSOLE
0086 help
0087 The virtual terminal is the device that interacts with the physical
0088 terminal through console drivers. On these systems, at least one
0089 console driver is loaded. In other configurations, additional console
0090 drivers may be enabled, such as the framebuffer console. If more than
0091 1 console driver is enabled, setting this to 'y' will allow you to
0092 select the console driver that will serve as the backend for the
0093 virtual terminals.
0094
0095 See <file:Documentation/driver-api/console.rst> for more
0096 information. For framebuffer console users, please refer to
0097 <file:Documentation/fb/fbcon.rst>.
0098
0099 config UNIX98_PTYS
0100 bool "Unix98 PTY support" if EXPERT
0101 default y
0102 help
0103 A pseudo terminal (PTY) is a software device consisting of two
0104 halves: a master and a slave. The slave device behaves identical to
0105 a physical terminal; the master device is used by a process to
0106 read data from and write data to the slave, thereby emulating a
0107 terminal. Typical programs for the master side are telnet servers
0108 and xterms.
0109
0110 Linux has traditionally used the BSD-like names /dev/ptyxx for
0111 masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
0112 has a number of problems. The GNU C library glibc 2.1 and later,
0113 however, supports the Unix98 naming standard: in order to acquire a
0114 pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
0115 terminal is then made available to the process and the pseudo
0116 terminal slave can be accessed as /dev/pts/<number>. What was
0117 traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
0118
0119 All modern Linux systems use the Unix98 ptys. Say Y unless
0120 you're on an embedded system and want to conserve memory.
0121
0122 config LEGACY_PTYS
0123 bool "Legacy (BSD) PTY support"
0124 default y
0125 help
0126 A pseudo terminal (PTY) is a software device consisting of two
0127 halves: a master and a slave. The slave device behaves identical to
0128 a physical terminal; the master device is used by a process to
0129 read data from and write data to the slave, thereby emulating a
0130 terminal. Typical programs for the master side are telnet servers
0131 and xterms.
0132
0133 Linux has traditionally used the BSD-like names /dev/ptyxx
0134 for masters and /dev/ttyxx for slaves of pseudo
0135 terminals. This scheme has a number of problems, including
0136 security. This option enables these legacy devices; on most
0137 systems, it is safe to say N.
0138
0139 config LEGACY_PTY_COUNT
0140 int "Maximum number of legacy PTY in use"
0141 depends on LEGACY_PTYS
0142 range 0 256
0143 default "256"
0144 help
0145 The maximum number of legacy PTYs that can be used at any one time.
0146 The default is 256, and should be more than enough. Embedded
0147 systems may want to reduce this to save memory.
0148
0149 When not in use, each legacy PTY occupies 12 bytes on 32-bit
0150 architectures and 24 bytes on 64-bit architectures.
0151
0152 config LDISC_AUTOLOAD
0153 bool "Automatically load TTY Line Disciplines"
0154 default y
0155 help
0156 Historically the kernel has always automatically loaded any
0157 line discipline that is in a kernel module when a user asks
0158 for it to be loaded with the TIOCSETD ioctl, or through other
0159 means. This is not always the best thing to do on systems
0160 where you know you will not be using some of the more
0161 "ancient" line disciplines, so prevent the kernel from doing
0162 this unless the request is coming from a process with the
0163 CAP_SYS_MODULE permissions.
0164
0165 Say 'Y' here if you trust your userspace users to do the right
0166 thing, or if you have only provided the line disciplines that
0167 you know you will be using, or if you wish to continue to use
0168 the traditional method of on-demand loading of these modules
0169 by any user.
0170
0171 This functionality can be changed at runtime with the
0172 dev.tty.ldisc_autoload sysctl, this configuration option will
0173 only set the default value of this functionality.
0174
0175 source "drivers/tty/serial/Kconfig"
0176
0177 config SERIAL_NONSTANDARD
0178 bool "Non-standard serial port support"
0179 depends on HAS_IOMEM
0180 help
0181 Say Y here if you have any non-standard serial boards -- boards
0182 which aren't supported using the standard "dumb" serial driver.
0183 This includes intelligent serial boards such as
0184 Digiboards, etc. These are usually used for systems that need many
0185 serial ports because they serve many terminals or dial-in
0186 connections.
0187
0188 Note that the answer to this question won't directly affect the
0189 kernel: saying N will just cause the configurator to skip all
0190 the questions about non-standard serial boards.
0191
0192 Most people can say N here.
0193
0194 config MOXA_INTELLIO
0195 tristate "Moxa Intellio support"
0196 depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
0197 select FW_LOADER
0198 help
0199 Say Y here if you have a Moxa Intellio multiport serial card.
0200
0201 To compile this driver as a module, choose M here: the
0202 module will be called moxa.
0203
0204 config MOXA_SMARTIO
0205 tristate "Moxa SmartIO support v. 2.0"
0206 depends on SERIAL_NONSTANDARD && PCI
0207 help
0208 Say Y here if you have a Moxa SmartIO multiport serial card and/or
0209 want to help develop a new version of this driver.
0210
0211 This is upgraded (1.9.1) driver from original Moxa drivers with
0212 changes finally resulting in PCI probing.
0213
0214 This driver can also be built as a module. The module will be called
0215 mxser. If you want to do that, say M here.
0216
0217 config SYNCLINK_GT
0218 tristate "SyncLink GT/AC support"
0219 depends on SERIAL_NONSTANDARD && PCI
0220 help
0221 Support for SyncLink GT and SyncLink AC families of
0222 synchronous and asynchronous serial adapters
0223 manufactured by Microgate Systems, Ltd. (www.microgate.com)
0224
0225 config N_HDLC
0226 tristate "HDLC line discipline support"
0227 depends on SERIAL_NONSTANDARD
0228 help
0229 Allows synchronous HDLC communications with tty device drivers that
0230 support synchronous HDLC such as the Microgate SyncLink adapter.
0231
0232 This driver can be built as a module ( = code which can be
0233 inserted in and removed from the running kernel whenever you want).
0234 The module will be called n_hdlc. If you want to do that, say M
0235 here.
0236
0237 config PPC_EPAPR_HV_BYTECHAN
0238 bool "ePAPR hypervisor byte channel driver"
0239 depends on PPC
0240 select EPAPR_PARAVIRT
0241 help
0242 This driver creates /dev entries for each ePAPR hypervisor byte
0243 channel, thereby allowing applications to communicate with byte
0244 channels as if they were serial ports.
0245
0246 config PPC_EARLY_DEBUG_EHV_BC
0247 bool "Early console (udbg) support for ePAPR hypervisors"
0248 depends on PPC_EPAPR_HV_BYTECHAN=y
0249 help
0250 Select this option to enable early console (a.k.a. "udbg") support
0251 via an ePAPR byte channel. You also need to choose the byte channel
0252 handle below.
0253
0254 config PPC_EARLY_DEBUG_EHV_BC_HANDLE
0255 int "Byte channel handle for early console (udbg)"
0256 depends on PPC_EARLY_DEBUG_EHV_BC
0257 default 0
0258 help
0259 If you want early console (udbg) output through a byte channel,
0260 specify the handle of the byte channel to use.
0261
0262 For this to work, the byte channel driver must be compiled
0263 in-kernel, not as a module.
0264
0265 Note that only one early console driver can be enabled, so don't
0266 enable any others if you enable this one.
0267
0268 If the number you specify is not a valid byte channel handle, then
0269 there simply will be no early console output. This is true also
0270 if you don't boot under a hypervisor at all.
0271
0272 config GOLDFISH_TTY
0273 tristate "Goldfish TTY Driver"
0274 depends on GOLDFISH
0275 select SERIAL_CORE
0276 select SERIAL_CORE_CONSOLE
0277 help
0278 Console and system TTY driver for the Goldfish virtual platform.
0279
0280 config GOLDFISH_TTY_EARLY_CONSOLE
0281 bool
0282 default y if GOLDFISH_TTY=y
0283 select SERIAL_EARLYCON
0284
0285 config N_GSM
0286 tristate "GSM MUX line discipline support (EXPERIMENTAL)"
0287 depends on NET
0288 help
0289 This line discipline provides support for the GSM MUX protocol and
0290 presents the mux as a set of 61 individual tty devices.
0291
0292 config NOZOMI
0293 tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
0294 depends on PCI
0295 help
0296 If you have a HSDPA driver Broadband Wireless Data Card -
0297 Globe Trotter PCMCIA card, say Y here.
0298
0299 To compile this driver as a module, choose M here, the module
0300 will be called nozomi.
0301
0302 config MIPS_EJTAG_FDC_TTY
0303 bool "MIPS EJTAG Fast Debug Channel TTY"
0304 depends on MIPS_CDMM
0305 help
0306 This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
0307 if they are present. This can be useful when working with an EJTAG
0308 probe which supports it, to get console output and a login prompt via
0309 EJTAG without needing to connect a serial cable.
0310
0311 TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
0312 CPU3).
0313
0314 The console can be enabled with console=fdc1 (for FDC channel 1 on all
0315 CPUs). Do not use the console unless there is a debug probe attached
0316 to drain the FDC TX FIFO.
0317
0318 If unsure, say N.
0319
0320 config MIPS_EJTAG_FDC_EARLYCON
0321 bool "Early FDC console"
0322 depends on MIPS_EJTAG_FDC_TTY
0323 help
0324 This registers a console on FDC channel 1 very early during boot (from
0325 MIPS arch code). This is useful for bring-up and debugging early boot
0326 issues.
0327
0328 Do not enable unless there is a debug probe attached to drain the FDC
0329 TX FIFO.
0330
0331 If unsure, say N.
0332
0333 config MIPS_EJTAG_FDC_KGDB
0334 bool "Use KGDB over an FDC channel"
0335 depends on MIPS_EJTAG_FDC_TTY && KGDB
0336 default y
0337 help
0338 This enables the use of KGDB over an FDC channel, allowing KGDB to be
0339 used remotely or when a serial port isn't available.
0340
0341 config MIPS_EJTAG_FDC_KGDB_CHAN
0342 int "KGDB FDC channel"
0343 depends on MIPS_EJTAG_FDC_KGDB
0344 range 2 15
0345 default 3
0346 help
0347 FDC channel number to use for KGDB.
0348
0349 config NULL_TTY
0350 tristate "NULL TTY driver"
0351 help
0352 Say Y here if you want a NULL TTY which simply discards messages.
0353
0354 This is useful to allow userspace applications which expect a console
0355 device to work without modifications even when no console is
0356 available or desired.
0357
0358 In order to use this driver, you should redirect the console to this
0359 TTY, or boot the kernel with console=ttynull.
0360
0361 If unsure, say N.
0362
0363 config VCC
0364 tristate "Sun Virtual Console Concentrator"
0365 depends on SUN_LDOMS
0366 help
0367 Support for Sun logical domain consoles.
0368
0369 source "drivers/tty/hvc/Kconfig"
0370
0371 config RPMSG_TTY
0372 tristate "RPMSG tty driver"
0373 depends on RPMSG
0374 help
0375 Say y here to export rpmsg endpoints as tty devices, usually found
0376 in /dev/ttyRPMSGx.
0377 This makes it possible for user-space programs to send and receive
0378 rpmsg messages as a standard tty protocol.
0379
0380 To compile this driver as a module, choose M here: the module will be
0381 called rpmsg_tty.
0382
0383 endif # TTY
0384
0385 source "drivers/tty/serdev/Kconfig"
