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+[[!meta copyright="Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2011
+Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+The Hurd console's implementation is broken into two pieces each running on
+it's own process, the console client and server.
+
+The console client is also split into modules (input driver, display driver,
+speaker, ...) but they all run in the same process.
+
+The console server puts itself as a translator on top of `/dev/vcs` folder
+presenting the following hierarchy:
+
+ + /dev/vcs
+ \
+ +- 1
+ \
+ +- console
+ +- input
+ +- display
+ +- ..
+ +- n
+
+where the numbered nodes represent virtual consoles and their contents are all
+alike.
+
+As the following graph shows, the console, input and display nodes are the
+interfaces used by the terminal server, input driver and display drivers
+respectively.
+
+ +------------------+ +-----------------+
+ | Input driver | | Terminal Server |
+ | | | |
+ | pc-kbd | | |
+ +------------------+ +-----------------+
+ | _cons_vcons_input |
+ | writes to reads |
+ | vcs/i/input vcs/i/console |
+ | +-----------------+ |
+ | | Console Server | |
+ | | /hurd/console | |
+ | input_enqueue | --------------- | input_dequeue |
+ +--------------->| Input Queue |>---------------+
+ | --------------- |
+ +--------------->| Output Buffer |>---------------+
+ | +-----------------+ |
+ | |
+ | writes reads |
+ | vcs/i/console vcs/i/display |
+ | |
+ +----------------+ +-----------------+
+ | Teminal Server | | Display driver |
+ | | | |
+ | /hurd/term | | vga |
+ +----------------+ +-----------------+
+
+The input driver takes scancodes from the in-kernel kbd queue, translates them
+into characters and writes them to the input node. Then the terminal server
+reads the console node taking the characters out of the console server.
+
+Each of theese actions is actually an RPC handled by the translator on
+`/dev/vcs`. Writes to input nodes are handled by calling `input_enqueue` to
+put the character into a queue. And reads from console nodes are handled by
+calling `input_dequeue` which takes out charecters from the queue and gives
+them to the reader.
+
+It's important to note here that both `input_enqueue` and `input_dequeue` are
+blocking operations and a blocked `input_dequeue` necessarily needs an
+`input_enqueue` call to continue.
+
+[[RPC]]s are handled by the console server with the help of [[hurd/libports]]'
+`ports_manage_multithreaded` API.
+
+
+---
+
+/!\ old content; [[!taglink open_issue_documentation]]: cleanup needed.
+
The below is a reworked version of Marcus Brinkmann's [letter to the debian-hurd list](http://lists.debian.org/debian-hurd/2002/debian-hurd-200209/msg00054.html). It describes how to setup the new console server for the Hurd. I am testing this right now, so this document is a work in progress.
-- [[Main/JoachimNilsson]] - 21 Jan 2003