417 lines
15 KiB
Plaintext
417 lines
15 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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config TTY
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bool "Enable TTY" if EXPERT
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default y
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help
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Allows you to remove TTY support which can save space, and
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blocks features that require TTY from inclusion in the kernel.
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TTY is required for any text terminals or serial port
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communication. Most users should leave this enabled.
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if TTY
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config VT
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bool "Virtual terminal" if EXPERT
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select INPUT
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default y if !UML
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help
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If you say Y here, you will get support for terminal devices with
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display and keyboard devices. These are called "virtual" because you
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can run several virtual terminals (also called virtual consoles) on
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one physical terminal. This is rather useful, for example one
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virtual terminal can collect system messages and warnings, another
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one can be used for a text-mode user session, and a third could run
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an X session, all in parallel. Switching between virtual terminals
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is done with certain key combinations, usually Alt-<function key>.
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The setterm command ("man setterm") can be used to change the
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properties (such as colors or beeping) of a virtual terminal. The
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man page console_codes(4) ("man console_codes") contains the special
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character sequences that can be used to change those properties
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directly. The fonts used on virtual terminals can be changed with
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the setfont ("man setfont") command and the key bindings are defined
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with the loadkeys ("man loadkeys") command.
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You need at least one virtual terminal device in order to make use
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of your keyboard and monitor. Therefore, only people configuring an
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embedded system would want to say N here in order to save some
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memory; the only way to log into such a system is then via a serial
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or network connection.
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If unsure, say Y, or else you won't be able to do much with your new
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shiny Linux system :-)
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config CONSOLE_TRANSLATIONS
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depends on VT
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default y
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bool "Enable character translations in console" if EXPERT
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help
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This enables support for font mapping and Unicode translation
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on virtual consoles.
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config VT_CONSOLE
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bool "Support for console on virtual terminal" if EXPERT
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depends on VT
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default y
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help
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The system console is the device which receives all kernel messages
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and warnings and which allows logins in single user mode. If you
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answer Y here, a virtual terminal (the device used to interact with
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a physical terminal) can be used as system console. This is the most
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common mode of operations, so you should say Y here unless you want
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the kernel messages be output only to a serial port (in which case
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you should say Y to "Console on serial port", below).
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If you do say Y here, by default the currently visible virtual
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terminal (/dev/tty0) will be used as system console. You can change
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that with a kernel command line option such as "console=tty3" which
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would use the third virtual terminal as system console. (Try "man
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bootparam" or see the documentation of your boot loader (lilo or
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loadlin) about how to pass options to the kernel at boot time.)
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If unsure, say Y.
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config VT_CONSOLE_SLEEP
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def_bool y
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depends on VT_CONSOLE && PM_SLEEP
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config HW_CONSOLE
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bool
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depends on VT
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default y
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config VT_HW_CONSOLE_BINDING
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bool "Support for binding and unbinding console drivers"
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depends on HW_CONSOLE
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help
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The virtual terminal is the device that interacts with the physical
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terminal through console drivers. On these systems, at least one
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console driver is loaded. In other configurations, additional console
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drivers may be enabled, such as the framebuffer console. If more than
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1 console driver is enabled, setting this to 'y' will allow you to
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select the console driver that will serve as the backend for the
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virtual terminals.
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See <file:Documentation/driver-api/console.rst> for more
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information. For framebuffer console users, please refer to
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<file:Documentation/fb/fbcon.rst>.
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config UNIX98_PTYS
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bool "Unix98 PTY support" if EXPERT
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default y
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help
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A pseudo terminal (PTY) is a software device consisting of two
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halves: a master and a slave. The slave device behaves identical to
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a physical terminal; the master device is used by a process to
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read data from and write data to the slave, thereby emulating a
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terminal. Typical programs for the master side are telnet servers
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and xterms.
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Linux has traditionally used the BSD-like names /dev/ptyxx for
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masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
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has a number of problems. The GNU C library glibc 2.1 and later,
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however, supports the Unix98 naming standard: in order to acquire a
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pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
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terminal is then made available to the process and the pseudo
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terminal slave can be accessed as /dev/pts/<number>. What was
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traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
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All modern Linux systems use the Unix98 ptys. Say Y unless
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you're on an embedded system and want to conserve memory.
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config LEGACY_PTYS
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bool "Legacy (BSD) PTY support"
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default y
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help
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A pseudo terminal (PTY) is a software device consisting of two
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halves: a master and a slave. The slave device behaves identical to
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a physical terminal; the master device is used by a process to
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read data from and write data to the slave, thereby emulating a
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terminal. Typical programs for the master side are telnet servers
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and xterms.
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Linux has traditionally used the BSD-like names /dev/ptyxx
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for masters and /dev/ttyxx for slaves of pseudo
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terminals. This scheme has a number of problems, including
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security. This option enables these legacy devices; on most
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systems, it is safe to say N.
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config LEGACY_PTY_COUNT
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int "Maximum number of legacy PTY in use"
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depends on LEGACY_PTYS
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range 0 256
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default "256"
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help
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The maximum number of legacy PTYs that can be used at any one time.
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The default is 256, and should be more than enough. Embedded
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systems may want to reduce this to save memory.
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When not in use, each legacy PTY occupies 12 bytes on 32-bit
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architectures and 24 bytes on 64-bit architectures.
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config LEGACY_TIOCSTI
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bool "Allow legacy TIOCSTI usage"
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default y
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help
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Historically the kernel has allowed TIOCSTI, which will push
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characters into a controlling TTY. This continues to be used
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as a malicious privilege escalation mechanism, and provides no
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meaningful real-world utility any more. Its use is considered
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a dangerous legacy operation, and can be disabled on most
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systems.
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Say Y here only if you have confirmed that your system's
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userspace depends on this functionality to continue operating
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normally.
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Processes which run with CAP_SYS_ADMIN, such as BRLTTY, can
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use TIOCSTI even when this is set to N.
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This functionality can be changed at runtime with the
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dev.tty.legacy_tiocsti sysctl. This configuration option sets
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the default value of the sysctl.
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config LDISC_AUTOLOAD
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bool "Automatically load TTY Line Disciplines"
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default y
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help
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Historically the kernel has always automatically loaded any
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line discipline that is in a kernel module when a user asks
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for it to be loaded with the TIOCSETD ioctl, or through other
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means. This is not always the best thing to do on systems
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where you know you will not be using some of the more
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"ancient" line disciplines, so prevent the kernel from doing
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this unless the request is coming from a process with the
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CAP_SYS_MODULE permissions.
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Say 'Y' here if you trust your userspace users to do the right
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thing, or if you have only provided the line disciplines that
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you know you will be using, or if you wish to continue to use
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the traditional method of on-demand loading of these modules
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by any user.
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This functionality can be changed at runtime with the
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dev.tty.ldisc_autoload sysctl, this configuration option will
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only set the default value of this functionality.
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source "drivers/tty/serial/Kconfig"
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config SERIAL_NONSTANDARD
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bool "Non-standard serial port support"
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depends on HAS_IOMEM
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help
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Say Y here if you have any non-standard serial boards -- boards
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which aren't supported using the standard "dumb" serial driver.
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This includes intelligent serial boards such as
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Digiboards, etc. These are usually used for systems that need many
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serial ports because they serve many terminals or dial-in
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connections.
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Note that the answer to this question won't directly affect the
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kernel: saying N will just cause the configurator to skip all
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the questions about non-standard serial boards.
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Most people can say N here.
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config MOXA_INTELLIO
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tristate "Moxa Intellio support"
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depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
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select FW_LOADER
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help
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Say Y here if you have a Moxa Intellio multiport serial card.
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To compile this driver as a module, choose M here: the
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module will be called moxa.
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config MOXA_SMARTIO
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tristate "Moxa SmartIO support v. 2.0"
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depends on SERIAL_NONSTANDARD && PCI
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help
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Say Y here if you have a Moxa SmartIO multiport serial card and/or
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want to help develop a new version of this driver.
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This is upgraded (1.9.1) driver from original Moxa drivers with
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changes finally resulting in PCI probing.
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This driver can also be built as a module. The module will be called
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mxser. If you want to do that, say M here.
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config SYNCLINK_GT
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tristate "SyncLink GT/AC support"
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depends on SERIAL_NONSTANDARD && PCI
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help
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Support for SyncLink GT and SyncLink AC families of
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synchronous and asynchronous serial adapters
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manufactured by Microgate Systems, Ltd. (www.microgate.com)
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config N_HDLC
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tristate "HDLC line discipline support"
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depends on SERIAL_NONSTANDARD
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help
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Allows synchronous HDLC communications with tty device drivers that
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support synchronous HDLC such as the Microgate SyncLink adapter.
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This driver can be built as a module ( = code which can be
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inserted in and removed from the running kernel whenever you want).
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The module will be called n_hdlc. If you want to do that, say M
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here.
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config PPC_EPAPR_HV_BYTECHAN
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bool "ePAPR hypervisor byte channel driver"
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depends on PPC
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select EPAPR_PARAVIRT
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help
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This driver creates /dev entries for each ePAPR hypervisor byte
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channel, thereby allowing applications to communicate with byte
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channels as if they were serial ports.
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config PPC_EARLY_DEBUG_EHV_BC
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bool "Early console (udbg) support for ePAPR hypervisors"
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depends on PPC_EPAPR_HV_BYTECHAN=y
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help
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Select this option to enable early console (a.k.a. "udbg") support
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via an ePAPR byte channel. You also need to choose the byte channel
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handle below.
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config PPC_EARLY_DEBUG_EHV_BC_HANDLE
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int "Byte channel handle for early console (udbg)"
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depends on PPC_EARLY_DEBUG_EHV_BC
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default 0
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help
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If you want early console (udbg) output through a byte channel,
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specify the handle of the byte channel to use.
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For this to work, the byte channel driver must be compiled
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in-kernel, not as a module.
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Note that only one early console driver can be enabled, so don't
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enable any others if you enable this one.
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If the number you specify is not a valid byte channel handle, then
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there simply will be no early console output. This is true also
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if you don't boot under a hypervisor at all.
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config GOLDFISH_TTY
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tristate "Goldfish TTY Driver"
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depends on GOLDFISH
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select SERIAL_CORE
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select SERIAL_CORE_CONSOLE
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help
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Console and system TTY driver for the Goldfish virtual platform.
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config GOLDFISH_TTY_EARLY_CONSOLE
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bool
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default y if GOLDFISH_TTY=y
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select SERIAL_EARLYCON
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config IPWIRELESS
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tristate "IPWireless 3G UMTS PCMCIA card support"
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depends on PCMCIA && NETDEVICES
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select PPP
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help
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This is a driver for 3G UMTS PCMCIA card from IPWireless company. In
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some countries (for example Czech Republic, T-Mobile ISP) this card
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is shipped for service called UMTS 4G.
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config N_GSM
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tristate "GSM MUX line discipline support (EXPERIMENTAL)"
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depends on NET
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help
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This line discipline provides support for the GSM MUX protocol and
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presents the mux as a set of 61 individual tty devices.
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config NOZOMI
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tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
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depends on PCI
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help
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If you have a HSDPA driver Broadband Wireless Data Card -
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Globe Trotter PCMCIA card, say Y here.
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To compile this driver as a module, choose M here, the module
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will be called nozomi.
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config MIPS_EJTAG_FDC_TTY
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bool "MIPS EJTAG Fast Debug Channel TTY"
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depends on MIPS_CDMM
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help
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This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
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if they are present. This can be useful when working with an EJTAG
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probe which supports it, to get console output and a login prompt via
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EJTAG without needing to connect a serial cable.
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TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
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CPU3).
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The console can be enabled with console=fdc1 (for FDC channel 1 on all
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CPUs). Do not use the console unless there is a debug probe attached
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to drain the FDC TX FIFO.
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If unsure, say N.
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config MIPS_EJTAG_FDC_EARLYCON
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bool "Early FDC console"
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depends on MIPS_EJTAG_FDC_TTY
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help
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This registers a console on FDC channel 1 very early during boot (from
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MIPS arch code). This is useful for bring-up and debugging early boot
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issues.
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Do not enable unless there is a debug probe attached to drain the FDC
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TX FIFO.
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If unsure, say N.
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config MIPS_EJTAG_FDC_KGDB
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bool "Use KGDB over an FDC channel"
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depends on MIPS_EJTAG_FDC_TTY && KGDB
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default y
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help
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This enables the use of KGDB over an FDC channel, allowing KGDB to be
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used remotely or when a serial port isn't available.
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config MIPS_EJTAG_FDC_KGDB_CHAN
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int "KGDB FDC channel"
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depends on MIPS_EJTAG_FDC_KGDB
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range 2 15
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default 3
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help
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FDC channel number to use for KGDB.
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config NULL_TTY
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tristate "NULL TTY driver"
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help
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Say Y here if you want a NULL TTY which simply discards messages.
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This is useful to allow userspace applications which expect a console
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device to work without modifications even when no console is
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available or desired.
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In order to use this driver, you should redirect the console to this
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TTY, or boot the kernel with console=ttynull.
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If unsure, say N.
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config VCC
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tristate "Sun Virtual Console Concentrator"
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depends on SUN_LDOMS
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help
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Support for Sun logical domain consoles.
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source "drivers/tty/hvc/Kconfig"
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config RPMSG_TTY
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tristate "RPMSG tty driver"
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depends on RPMSG
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help
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Say y here to export rpmsg endpoints as tty devices, usually found
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in /dev/ttyRPMSGx.
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This makes it possible for user-space programs to send and receive
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rpmsg messages as a standard tty protocol.
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To compile this driver as a module, choose M here: the module will be
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called rpmsg_tty.
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endif # TTY
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source "drivers/tty/serdev/Kconfig"
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