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# SPDX-License-Identifier: GPL-2.0 config TTY bool "Enable TTY" if EXPERT default y ---help--- Allows you to remove TTY support which can save space, and blocks features that require TTY from inclusion in the kernel. TTY is required for any text terminals or serial port communication. Most users should leave this enabled. if TTY config VT bool "Virtual terminal" if EXPERT depends on !UML select INPUT default y ---help--- If you say Y here, you will get support for terminal devices with display and keyboard devices. These are called "virtual" because you can run several virtual terminals (also called virtual consoles) on one physical terminal. This is rather useful, for example one virtual terminal can collect system messages and warnings, another one can be used for a text-mode user session, and a third could run an X session, all in parallel. Switching between virtual terminals is done with certain key combinations, usually Alt-<function key>. The setterm command ("man setterm") can be used to change the properties (such as colors or beeping) of a virtual terminal. The man page console_codes(4) ("man console_codes") contains the special character sequences that can be used to change those properties directly. The fonts used on virtual terminals can be changed with the setfont ("man setfont") command and the key bindings are defined with the loadkeys ("man loadkeys") command. You need at least one virtual terminal device in order to make use of your keyboard and monitor. Therefore, only people configuring an embedded system would want to say N here in order to save some memory; the only way to log into such a system is then via a serial or network connection. If unsure, say Y, or else you won't be able to do much with your new shiny Linux system :-) config CONSOLE_TRANSLATIONS depends on VT default y bool "Enable character translations in console" if EXPERT ---help--- This enables support for font mapping and Unicode translation on virtual consoles. config VT_CONSOLE bool "Support for console on virtual terminal" if EXPERT depends on VT default y ---help--- The system console is the device which receives all kernel messages and warnings and which allows logins in single user mode. If you answer Y here, a virtual terminal (the device used to interact with a physical terminal) can be used as system console. This is the most common mode of operations, so you should say Y here unless you want the kernel messages be output only to a serial port (in which case you should say Y to "Console on serial port", below). If you do say Y here, by default the currently visible virtual terminal (/dev/tty0) will be used as system console. You can change that with a kernel command line option such as "console=tty3" which would use the third virtual terminal as system console. (Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.) If unsure, say Y. config VT_CONSOLE_SLEEP def_bool y depends on VT_CONSOLE && PM_SLEEP config HW_CONSOLE bool depends on VT && !UML default y config VT_HW_CONSOLE_BINDING bool "Support for binding and unbinding console drivers" depends on HW_CONSOLE ---help--- The virtual terminal is the device that interacts with the physical terminal through console drivers. On these systems, at least one console driver is loaded. In other configurations, additional console drivers may be enabled, such as the framebuffer console. If more than 1 console driver is enabled, setting this to 'y' will allow you to select the console driver that will serve as the backend for the virtual terminals. See <file:Documentation/driver-api/console.rst> for more information. For framebuffer console users, please refer to <file:Documentation/fb/fbcon.rst>. config UNIX98_PTYS bool "Unix98 PTY support" if EXPERT default y ---help--- A pseudo terminal (PTY) is a software device consisting of two halves: a master and a slave. The slave device behaves identical to a physical terminal; the master device is used by a process to read data from and write data to the slave, thereby emulating a terminal. Typical programs for the master side are telnet servers and xterms. Linux has traditionally used the BSD-like names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals. This scheme has a number of problems. The GNU C library glibc 2.1 and later, however, supports the Unix98 naming standard: in order to acquire a pseudo terminal, a process opens /dev/ptmx; the number of the pseudo terminal is then made available to the process and the pseudo terminal slave can be accessed as /dev/pts/<number>. What was traditionally /dev/ttyp2 will then be /dev/pts/2, for example. All modern Linux systems use the Unix98 ptys. Say Y unless you're on an embedded system and want to conserve memory. config LEGACY_PTYS bool "Legacy (BSD) PTY support" default y ---help--- A pseudo terminal (PTY) is a software device consisting of two halves: a master and a slave. The slave device behaves identical to a physical terminal; the master device is used by a process to read data from and write data to the slave, thereby emulating a terminal. Typical programs for the master side are telnet servers and xterms. Linux has traditionally used the BSD-like names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals. This scheme has a number of problems, including security. This option enables these legacy devices; on most systems, it is safe to say N. config LEGACY_PTY_COUNT int "Maximum number of legacy PTY in use" depends on LEGACY_PTYS range 0 256 default "256" ---help--- The maximum number of legacy PTYs that can be used at any one time. The default is 256, and should be more than enough. Embedded systems may want to reduce this to save memory. When not in use, each legacy PTY occupies 12 bytes on 32-bit architectures and 24 bytes on 64-bit architectures. config SERIAL_NONSTANDARD bool "Non-standard serial port support" depends on HAS_IOMEM ---help--- Say Y here if you have any non-standard serial boards -- boards which aren't supported using the standard "dumb" serial driver. This includes intelligent serial boards such as Cyclades, Digiboards, etc. These are usually used for systems that need many serial ports because they serve many terminals or dial-in connections. Note that the answer to this question won't directly affect the kernel: saying N will just cause the configurator to skip all the questions about non-standard serial boards. Most people can say N here. config ROCKETPORT tristate "Comtrol RocketPort support" depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI) help This driver supports Comtrol RocketPort and RocketModem PCI boards. These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or modems. For information about the RocketPort/RocketModem boards and this driver read <file:Documentation/driver-api/serial/rocket.rst>. To compile this driver as a module, choose M here: the module will be called rocket. If you want to compile this driver into the kernel, say Y here. If you don't have a Comtrol RocketPort/RocketModem card installed, say N. config CYCLADES tristate "Cyclades async mux support" depends on SERIAL_NONSTANDARD && (PCI || ISA) select FW_LOADER ---help--- This driver supports Cyclades Z and Y multiserial boards. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server. For information about the Cyclades-Z card, read <file:Documentation/driver-api/serial/cyclades_z.rst>. To compile this driver as a module, choose M here: the module will be called cyclades. If you haven't heard about it, it's safe to say N. config CYZ_INTR bool "Cyclades-Z interrupt mode operation" depends on CYCLADES && PCI help The Cyclades-Z family of multiport cards allows 2 (two) driver op modes: polling and interrupt. In polling mode, the driver will check the status of the Cyclades-Z ports every certain amount of time (which is called polling cycle and is configurable). In interrupt mode, it will use an interrupt line (IRQ) in order to check the status of the Cyclades-Z ports. The default op mode is polling. If unsure, say N. config MOXA_INTELLIO tristate "Moxa Intellio support" depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI) select FW_LOADER help Say Y here if you have a Moxa Intellio multiport serial card. To compile this driver as a module, choose M here: the module will be called moxa. config MOXA_SMARTIO tristate "Moxa SmartIO support v. 2.0" depends on SERIAL_NONSTANDARD && (PCI || EISA || ISA) help Say Y here if you have a Moxa SmartIO multiport serial card and/or want to help develop a new version of this driver. This is upgraded (1.9.1) driver from original Moxa drivers with changes finally resulting in PCI probing. This driver can also be built as a module. The module will be called mxser. If you want to do that, say M here. config SYNCLINK tristate "Microgate SyncLink card support" depends on SERIAL_NONSTANDARD && PCI && ISA_DMA_API help Provides support for the SyncLink ISA and PCI multiprotocol serial adapters. These adapters support asynchronous and HDLC bit synchronous communication up to 10Mbps (PCI adapter). This driver can only be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called synclink. If you want to do that, say M here. config SYNCLINKMP tristate "SyncLink Multiport support" depends on SERIAL_NONSTANDARD && PCI help Enable support for the SyncLink Multiport (2 or 4 ports) serial adapter, running asynchronous and HDLC communications up to 2.048Mbps. Each ports is independently selectable for RS-232, V.35, RS-449, RS-530, and X.21 This driver may be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called synclinkmp. If you want to do that, say M here. config SYNCLINK_GT tristate "SyncLink GT/AC support" depends on SERIAL_NONSTANDARD && PCI help Support for SyncLink GT and SyncLink AC families of synchronous and asynchronous serial adapters manufactured by Microgate Systems, Ltd. (www.microgate.com) config NOZOMI tristate "HSDPA Broadband Wireless Data Card - Globe Trotter" depends on PCI help If you have a HSDPA driver Broadband Wireless Data Card - Globe Trotter PCMCIA card, say Y here. To compile this driver as a module, choose M here, the module will be called nozomi. config ISI tristate "Multi-Tech multiport card support" depends on SERIAL_NONSTANDARD && PCI select FW_LOADER help This is a driver for the Multi-Tech cards which provide several serial ports. The driver is experimental and can currently only be built as a module. The module will be called isicom. If you want to do that, choose M here. config N_HDLC tristate "HDLC line discipline support" depends on SERIAL_NONSTANDARD help Allows synchronous HDLC communications with tty device drivers that support synchronous HDLC such as the Microgate SyncLink adapter. This driver can be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called n_hdlc. If you want to do that, say M here. config N_GSM tristate "GSM MUX line discipline support (EXPERIMENTAL)" depends on NET help This line discipline provides support for the GSM MUX protocol and presents the mux as a set of 61 individual tty devices. config TRACE_ROUTER tristate "Trace data router for MIPI P1149.7 cJTAG standard" depends on TRACE_SINK help The trace router uses the Linux tty line discipline framework to route trace data coming from a tty port (say UART for example) to the trace sink line discipline driver and to another tty port (say USB). This is part of a solution for the MIPI P1149.7, compact JTAG, standard, which is for debugging mobile devices. The PTI driver in drivers/misc/pti.c defines the majority of this MIPI solution. You should select this driver if the target kernel is meant for a mobile device containing a modem. Then you will need to select "Trace data sink for MIPI P1149.7 cJTAG standard" line discipline driver. config TRACE_SINK tristate "Trace data sink for MIPI P1149.7 cJTAG standard" help The trace sink uses the Linux line discipline framework to receive trace data coming from the trace router line discipline driver to a user-defined tty port target, like USB. This is to provide a way to extract modem trace data on devices that do not have a PTI HW module, or just need modem trace data to come out of a different HW output port. This is part of a solution for the P1149.7, compact JTAG, standard. If you select this option, you need to select "Trace data router for MIPI P1149.7 cJTAG standard". config PPC_EPAPR_HV_BYTECHAN bool "ePAPR hypervisor byte channel driver" depends on PPC select EPAPR_PARAVIRT help This driver creates /dev entries for each ePAPR hypervisor byte channel, thereby allowing applications to communicate with byte channels as if they were serial ports. config PPC_EARLY_DEBUG_EHV_BC bool "Early console (udbg) support for ePAPR hypervisors" depends on PPC_EPAPR_HV_BYTECHAN=y help Select this option to enable early console (a.k.a. "udbg") support via an ePAPR byte channel. You also need to choose the byte channel handle below. config PPC_EARLY_DEBUG_EHV_BC_HANDLE int "Byte channel handle for early console (udbg)" depends on PPC_EARLY_DEBUG_EHV_BC default 0 help If you want early console (udbg) output through a byte channel, specify the handle of the byte channel to use. For this to work, the byte channel driver must be compiled in-kernel, not as a module. Note that only one early console driver can be enabled, so don't enable any others if you enable this one. If the number you specify is not a valid byte channel handle, then there simply will be no early console output. This is true also if you don't boot under a hypervisor at all. config NULL_TTY tristate "NULL TTY driver" help Say Y here if you want a NULL TTY which simply discards messages. This is useful to allow userspace applications which expect a console device to work without modifications even when no console is available or desired. In order to use this driver, you should redirect the console to this TTY, or boot the kernel with console=ttynull. If unsure, say N. config GOLDFISH_TTY tristate "Goldfish TTY Driver" depends on GOLDFISH select SERIAL_CORE select SERIAL_CORE_CONSOLE help Console and system TTY driver for the Goldfish virtual platform. config GOLDFISH_TTY_EARLY_CONSOLE bool default y if GOLDFISH_TTY=y select SERIAL_EARLYCON config MIPS_EJTAG_FDC_TTY bool "MIPS EJTAG Fast Debug Channel TTY" depends on MIPS_CDMM help This enables a TTY and console on the MIPS EJTAG Fast Debug Channels, if they are present. This can be useful when working with an EJTAG probe which supports it, to get console output and a login prompt via EJTAG without needing to connect a serial cable. TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on CPU3). The console can be enabled with console=fdc1 (for FDC channel 1 on all CPUs). Do not use the console unless there is a debug probe attached to drain the FDC TX FIFO. If unsure, say N. config MIPS_EJTAG_FDC_EARLYCON bool "Early FDC console" depends on MIPS_EJTAG_FDC_TTY help This registers a console on FDC channel 1 very early during boot (from MIPS arch code). This is useful for bring-up and debugging early boot issues. Do not enable unless there is a debug probe attached to drain the FDC TX FIFO. If unsure, say N. config MIPS_EJTAG_FDC_KGDB bool "Use KGDB over an FDC channel" depends on MIPS_EJTAG_FDC_TTY && KGDB default y help This enables the use of KGDB over an FDC channel, allowing KGDB to be used remotely or when a serial port isn't available. config MIPS_EJTAG_FDC_KGDB_CHAN int "KGDB FDC channel" depends on MIPS_EJTAG_FDC_KGDB range 2 15 default 3 help FDC channel number to use for KGDB. config VCC tristate "Sun Virtual Console Concentrator" depends on SUN_LDOMS help Support for Sun logical domain consoles. config LDISC_AUTOLOAD bool "Automatically load TTY Line Disciplines" default y help Historically the kernel has always automatically loaded any line discipline that is in a kernel module when a user asks for it to be loaded with the TIOCSETD ioctl, or through other means. This is not always the best thing to do on systems where you know you will not be using some of the more "ancient" line disciplines, so prevent the kernel from doing this unless the request is coming from a process with the CAP_SYS_MODULE permissions. Say 'Y' here if you trust your userspace users to do the right thing, or if you have only provided the line disciplines that you know you will be using, or if you wish to continue to use the traditional method of on-demand loading of these modules by any user. This functionality can be changed at runtime with the dev.tty.ldisc_autoload sysctl, this configuration option will only set the default value of this functionality. endif # TTY