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1# SPDX-License-Identifier: GPL-2.02config TTY3 bool "Enable TTY" if EXPERT4 default y5 help6 Allows you to remove TTY support which can save space, and7 blocks features that require TTY from inclusion in the kernel.8 TTY is required for any text terminals or serial port9 communication. Most users should leave this enabled.10 11if TTY12 13config VT14 bool "Virtual terminal" if EXPERT15 select INPUT16 default y if !UML17 help18 If you say Y here, you will get support for terminal devices with19 display and keyboard devices. These are called "virtual" because you20 can run several virtual terminals (also called virtual consoles) on21 one physical terminal. This is rather useful, for example one22 virtual terminal can collect system messages and warnings, another23 one can be used for a text-mode user session, and a third could run24 an X session, all in parallel. Switching between virtual terminals25 is done with certain key combinations, usually Alt-<function key>.26 27 The setterm command ("man setterm") can be used to change the28 properties (such as colors or beeping) of a virtual terminal. The29 man page console_codes(4) ("man console_codes") contains the special30 character sequences that can be used to change those properties31 directly. The fonts used on virtual terminals can be changed with32 the setfont ("man setfont") command and the key bindings are defined33 with the loadkeys ("man loadkeys") command.34 35 You need at least one virtual terminal device in order to make use36 of your keyboard and monitor. Therefore, only people configuring an37 embedded system would want to say N here in order to save some38 memory; the only way to log into such a system is then via a serial39 or network connection.40 41 If unsure, say Y, or else you won't be able to do much with your new42 shiny Linux system :-)43 44config CONSOLE_TRANSLATIONS45 depends on VT46 default y47 bool "Enable character translations in console" if EXPERT48 help49 This enables support for font mapping and Unicode translation50 on virtual consoles.51 52config VT_CONSOLE53 bool "Support for console on virtual terminal" if EXPERT54 depends on VT55 default y56 help57 The system console is the device which receives all kernel messages58 and warnings and which allows logins in single user mode. If you59 answer Y here, a virtual terminal (the device used to interact with60 a physical terminal) can be used as system console. This is the most61 common mode of operations, so you should say Y here unless you want62 the kernel messages be output only to a serial port (in which case63 you should say Y to "Console on serial port", below).64 65 If you do say Y here, by default the currently visible virtual66 terminal (/dev/tty0) will be used as system console. You can change67 that with a kernel command line option such as "console=tty3" which68 would use the third virtual terminal as system console. (Try "man69 bootparam" or see the documentation of your boot loader (lilo or70 loadlin) about how to pass options to the kernel at boot time.)71 72 If unsure, say Y.73 74config VT_CONSOLE_SLEEP75 def_bool y76 depends on VT_CONSOLE && PM_SLEEP77 78config VT_HW_CONSOLE_BINDING79 bool "Support for binding and unbinding console drivers"80 depends on VT81 help82 The virtual terminal is the device that interacts with the physical83 terminal through console drivers. On these systems, at least one84 console driver is loaded. In other configurations, additional console85 drivers may be enabled, such as the framebuffer console. If more than86 1 console driver is enabled, setting this to 'y' will allow you to87 select the console driver that will serve as the backend for the88 virtual terminals.89 90 See <file:Documentation/driver-api/console.rst> for more91 information. For framebuffer console users, please refer to92 <file:Documentation/fb/fbcon.rst>.93 94config UNIX98_PTYS95 bool "Unix98 PTY support" if EXPERT96 default y97 help98 A pseudo terminal (PTY) is a software device consisting of two99 halves: a master and a slave. The slave device behaves identical to100 a physical terminal; the master device is used by a process to101 read data from and write data to the slave, thereby emulating a102 terminal. Typical programs for the master side are telnet servers103 and xterms.104 105 Linux has traditionally used the BSD-like names /dev/ptyxx for106 masters and /dev/ttyxx for slaves of pseudo terminals. This scheme107 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 a109 pseudo terminal, a process opens /dev/ptmx; the number of the pseudo110 terminal is then made available to the process and the pseudo111 terminal slave can be accessed as /dev/pts/<number>. What was112 traditionally /dev/ttyp2 will then be /dev/pts/2, for example.113 114 All modern Linux systems use the Unix98 ptys. Say Y unless115 you're on an embedded system and want to conserve memory.116 117config LEGACY_PTYS118 bool "Legacy (BSD) PTY support"119 default y120 help121 A pseudo terminal (PTY) is a software device consisting of two122 halves: a master and a slave. The slave device behaves identical to123 a physical terminal; the master device is used by a process to124 read data from and write data to the slave, thereby emulating a125 terminal. Typical programs for the master side are telnet servers126 and xterms.127 128 Linux has traditionally used the BSD-like names /dev/ptyxx129 for masters and /dev/ttyxx for slaves of pseudo130 terminals. This scheme has a number of problems, including131 security. This option enables these legacy devices; on most132 systems, it is safe to say N.133 134config LEGACY_PTY_COUNT135 int "Maximum number of legacy PTY in use"136 depends on LEGACY_PTYS137 range 0 256138 default "256"139 help140 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. Embedded142 systems may want to reduce this to save memory.143 144 When not in use, each legacy PTY occupies 12 bytes on 32-bit145 architectures and 24 bytes on 64-bit architectures.146 147config LEGACY_TIOCSTI148 bool "Allow legacy TIOCSTI usage"149 default y150 help151 Historically the kernel has allowed TIOCSTI, which will push152 characters into a controlling TTY. This continues to be used153 as a malicious privilege escalation mechanism, and provides no154 meaningful real-world utility any more. Its use is considered155 a dangerous legacy operation, and can be disabled on most156 systems.157 158 Say Y here only if you have confirmed that your system's159 userspace depends on this functionality to continue operating160 normally.161 162 Processes which run with CAP_SYS_ADMIN, such as BRLTTY, can163 use TIOCSTI even when this is set to N.164 165 This functionality can be changed at runtime with the166 dev.tty.legacy_tiocsti sysctl. This configuration option sets167 the default value of the sysctl.168 169config LDISC_AUTOLOAD170 bool "Automatically load TTY Line Disciplines"171 default y172 help173 Historically the kernel has always automatically loaded any174 line discipline that is in a kernel module when a user asks175 for it to be loaded with the TIOCSETD ioctl, or through other176 means. This is not always the best thing to do on systems177 where you know you will not be using some of the more178 "ancient" line disciplines, so prevent the kernel from doing179 this unless the request is coming from a process with the180 CAP_SYS_MODULE permissions.181 182 Say 'Y' here if you trust your userspace users to do the right183 thing, or if you have only provided the line disciplines that184 you know you will be using, or if you wish to continue to use185 the traditional method of on-demand loading of these modules186 by any user.187 188 This functionality can be changed at runtime with the189 dev.tty.ldisc_autoload sysctl, this configuration option will190 only set the default value of this functionality.191 192source "drivers/tty/serial/Kconfig"193 194config SERIAL_NONSTANDARD195 bool "Non-standard serial port support"196 depends on HAS_IOMEM197 help198 Say Y here if you have any non-standard serial boards -- boards199 which aren't supported using the standard "dumb" serial driver.200 This includes intelligent serial boards such as201 Digiboards, etc. These are usually used for systems that need many202 serial ports because they serve many terminals or dial-in203 connections.204 205 Note that the answer to this question won't directly affect the206 kernel: saying N will just cause the configurator to skip all207 the questions about non-standard serial boards.208 209 Most people can say N here.210 211config MOXA_INTELLIO212 tristate "Moxa Intellio support"213 depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)214 select FW_LOADER215 help216 Say Y here if you have a Moxa Intellio multiport serial card.217 218 To compile this driver as a module, choose M here: the219 module will be called moxa.220 221config MOXA_SMARTIO222 tristate "Moxa SmartIO support v. 2.0"223 depends on SERIAL_NONSTANDARD && PCI224 help225 Say Y here if you have a Moxa SmartIO multiport serial card and/or226 want to help develop a new version of this driver.227 228 This is upgraded (1.9.1) driver from original Moxa drivers with229 changes finally resulting in PCI probing.230 231 This driver can also be built as a module. The module will be called232 mxser. If you want to do that, say M here.233 234config SYNCLINK_GT235 tristate "SyncLink GT/AC support"236 depends on SERIAL_NONSTANDARD && PCI237 depends on BROKEN238 help239 Support for SyncLink GT and SyncLink AC families of240 synchronous and asynchronous serial adapters241 manufactured by Microgate Systems, Ltd. (www.microgate.com)242 243config N_HDLC244 tristate "HDLC line discipline support"245 depends on SERIAL_NONSTANDARD246 help247 Allows synchronous HDLC communications with tty device drivers that248 support synchronous HDLC such as the Microgate SyncLink adapter.249 250 This driver can be built as a module ( = code which can be251 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 M253 here.254 255config PPC_EPAPR_HV_BYTECHAN256 bool "ePAPR hypervisor byte channel driver"257 depends on PPC258 select EPAPR_PARAVIRT259 help260 This driver creates /dev entries for each ePAPR hypervisor byte261 channel, thereby allowing applications to communicate with byte262 channels as if they were serial ports.263 264config PPC_EARLY_DEBUG_EHV_BC265 bool "Early console (udbg) support for ePAPR hypervisors"266 depends on PPC_EPAPR_HV_BYTECHAN=y267 help268 Select this option to enable early console (a.k.a. "udbg") support269 via an ePAPR byte channel. You also need to choose the byte channel270 handle below.271 272config PPC_EARLY_DEBUG_EHV_BC_HANDLE273 int "Byte channel handle for early console (udbg)"274 depends on PPC_EARLY_DEBUG_EHV_BC275 default 0276 help277 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 compiled281 in-kernel, not as a module.282 283 Note that only one early console driver can be enabled, so don't284 enable any others if you enable this one.285 286 If the number you specify is not a valid byte channel handle, then287 there simply will be no early console output. This is true also288 if you don't boot under a hypervisor at all.289 290config GOLDFISH_TTY291 tristate "Goldfish TTY Driver"292 depends on GOLDFISH293 select SERIAL_CORE294 select SERIAL_CORE_CONSOLE295 help296 Console and system TTY driver for the Goldfish virtual platform.297 298config GOLDFISH_TTY_EARLY_CONSOLE299 bool300 default y if GOLDFISH_TTY=y301 select SERIAL_EARLYCON302 303config IPWIRELESS304 tristate "IPWireless 3G UMTS PCMCIA card support"305 depends on PCMCIA && NETDEVICES306 select PPP307 help308 This is a driver for 3G UMTS PCMCIA card from IPWireless company. In309 some countries (for example Czech Republic, T-Mobile ISP) this card310 is shipped for service called UMTS 4G.311 312config N_GSM313 tristate "GSM MUX line discipline support (EXPERIMENTAL)"314 depends on NET315 help316 This line discipline provides support for the GSM MUX protocol and317 presents the mux as a set of 61 individual tty devices.318 319config NOZOMI320 tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"321 depends on PCI322 help323 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 module327 will be called nozomi.328 329config MIPS_EJTAG_FDC_TTY330 bool "MIPS EJTAG Fast Debug Channel TTY"331 depends on MIPS_CDMM332 help333 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 EJTAG335 probe which supports it, to get console output and a login prompt via336 EJTAG without needing to connect a serial cable.337 338 TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on339 CPU3).340 341 The console can be enabled with console=fdc1 (for FDC channel 1 on all342 CPUs). Do not use the console unless there is a debug probe attached343 to drain the FDC TX FIFO.344 345 If unsure, say N.346 347config MIPS_EJTAG_FDC_EARLYCON348 bool "Early FDC console"349 depends on MIPS_EJTAG_FDC_TTY350 help351 This registers a console on FDC channel 1 very early during boot (from352 MIPS arch code). This is useful for bring-up and debugging early boot353 issues.354 355 Do not enable unless there is a debug probe attached to drain the FDC356 TX FIFO.357 358 If unsure, say N.359 360config MIPS_EJTAG_FDC_KGDB361 bool "Use KGDB over an FDC channel"362 depends on MIPS_EJTAG_FDC_TTY && KGDB363 default y364 help365 This enables the use of KGDB over an FDC channel, allowing KGDB to be366 used remotely or when a serial port isn't available.367 368config MIPS_EJTAG_FDC_KGDB_CHAN369 int "KGDB FDC channel"370 depends on MIPS_EJTAG_FDC_KGDB371 range 2 15372 default 3373 help374 FDC channel number to use for KGDB.375 376config NULL_TTY377 tristate "NULL TTY driver"378 help379 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 console382 device to work without modifications even when no console is383 available or desired.384 385 In order to use this driver, you should redirect the console to this386 TTY, or boot the kernel with console=ttynull.387 388 If unsure, say N.389 390config VCC391 tristate "Sun Virtual Console Concentrator"392 depends on SUN_LDOMS393 help394 Support for Sun logical domain consoles.395 396source "drivers/tty/hvc/Kconfig"397 398config RPMSG_TTY399 tristate "RPMSG tty driver"400 depends on RPMSG401 help402 Say y here to export rpmsg endpoints as tty devices, usually found403 in /dev/ttyRPMSGx.404 This makes it possible for user-space programs to send and receive405 rpmsg messages as a standard tty protocol.406 407 To compile this driver as a module, choose M here: the module will be408 called rpmsg_tty.409 410endif # TTY411 412source "drivers/tty/serdev/Kconfig"413