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 :-)
This enables support for font mapping and Unicode translation on virtual consoles.
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.
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/console/console.txt> for more information. For framebuffer console users, please refer to <file:Documentation/fb/fbcon.txt>.
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.
Enable support for multiple instances of devpts filesystem. If you want to have isolated PTY namespaces (eg: in containers), say Y here. Otherwise, say N. If enabled, each mount of devpts filesystem with the '-o newinstance' option will create an independent PTY namespace.
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.
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.
Add support for emulating a TTY device over the Blackfin JTAG. To compile this driver as a module, choose M here: the module will be called bfin_jtag_comm.
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.
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/serial/rocket.txt>. 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.
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/serial/README.cycladesZ>. 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.
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.
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.
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.
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.
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.
Support for SyncLink GT and SyncLink AC families of synchronous and asynchronous serial adapters manufactured by Microgate Systems, Ltd. (www.microgate.com)
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.
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.
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.
This line discipline provides support for the GSM MUX protocol and presents the mux as a set of 61 individual tty devices.
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.
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".