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Diffstat (limited to 'hurd/console.mdwn')
| -rw-r--r-- | hurd/console.mdwn | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/hurd/console.mdwn b/hurd/console.mdwn index 4f976efd..f7230011 100644 --- a/hurd/console.mdwn +++ b/hurd/console.mdwn @@ -1,3 +1,88 @@ +[[!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 |