kmscon

kmscon
Developer(s) David Herrmann
Initial release March 27, 2012 (2012-03-27)[1]
Stable release 8 / October 29, 2013 (2013-10-29)
Preview release 8 / October 29, 2013 (2013-10-29)
Development status Active
Written in C
Operating system Linux
Type System console
License ISC license
Website www.freedesktop.org/wiki/Software/kmscon

Kmscon is a virtual console which runs in userspace and intends to replace the Linux console, a terminal built into the Linux kernel. Kmscon uses the KMS driver for its output, it is multi-seat capable, supports internationalized keyboard input and UTF-8 terminal output. The input support is implemented using X keyboard extension (XKB). Development of Kmscon stopped in March 2015. There is a new project called systemd-consoled.

Features

Kmscon supports printing the full set of Unicode glyphs and is not limited by console encoding as the Linux console.[2] While the only hard dependency is udev, kmscon can optionally be compiled to use Mesa for hardware acceleration of the console, and the pango library for improved font rendering.[3]

The adoption of XKB for input allows kmscon to accept the full range of available keyboard layouts for the X.Org Server and Wayland compositors for input and makes it possible to use the same layout both in graphical environment and in terminal.[4]

Multi-seat

The VT system in the Linux kernel dates back to 1993 and does not understand the concept of multiple seats. It does support up to 63 VTs, but only a single seat, i.e. only one VT can be active at any given time. Nevertheless this limitation does not render multi-seat impossible, it only necessitates some additional steps to configure multi-seat as opposed to making it run out-of-the-box. kmscon/systemd-consoled will enable multi-seat out-of-the-box.

If one seat's display server is running on VT 7 and another seat's display server is running on VT 8, then only one of these two seats can be used at a time. To use the other seat, a VT switch must be initiated.

To make all seats usable at the same time, there are a few options:

Development

In 2011, Jesse Barnes wrote in his blog about the possible userspace DRM-based implementation of the virtual terminal, that would dissolve the need for the Linux framebuffer and virtual terminal (VT) subsystems in the Linux kernel. Motivated by this blog post, David Herrmann implemented the basic functionality of virtual terminal.[2]

In October 2013, terminal emulator state machine (libtsm) library, a state machine for DEC VT100-VT520 compatible terminal emulators, was split out of kmscon and made available separately.[5] It was amended with wlterm, an example Wayland terminal emulator.[6]

See also

References

  1. ↑ Herrmann, David (March 27, 2012), "[ANNOUNCE] kmscon: Lazy-web's DRM based terminal emulator", dri-devel mailing list (freedesktop.org), retrieved April 2, 2012
  2. 1 2 Larabel, Michael (March 28, 2012), "KMSCON: A DRM-Based Terminal Emulator", Phoronix, retrieved April 2, 2012
  3. ↑ Larabel, Michael (August 18, 2012), "KMSCON Is Getting Ready To Kick The Kernel Console", Phoronix, retrieved July 5, 2012
  4. ↑ Herrmann, David (December 10, 2012), KMSCON Introduction, retrieved May 8, 2013
  5. ↑ Herrmann, David (October 29, 2013), "[ANNOUNCE] libtsm-3 release", kmscon-devel mailing list (freedesktop.org), retrieved July 5, 2012
  6. ↑ libtsm, freedesktop.org, retrieved July 5, 2012
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