OptionsEditor

Revision 4 as of 2008-06-03 10:39:42

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Summary

Implements an xorg.conf editor for adding/removing/changing driver and server options. This is done in two phases: The first phase simply establishes the foundations (parser, backend, etc.) and provides for setting the "Virtual" Option. The second phase implements the full GUI editing capability.

Rationale

Xorg's configuration system has matured greatly in recent years, to the point that editing xorg.conf is usually unnecessary: the X server autodetects pretty much everything, and distro install scripts can largely take care of the remainder. With the introduction of Xrandr, many common configuration tasks (like setting resolutions) that used to be done by editing xorg.conf and restarting can now be done at run-time using GUI tools like Screen Resolution.

However, there are still many little corner cases where the user will need or wish to make adjustments to X that can currently only be done in xorg.conf; largely, these cases involve setting one or more Options either in a Device section or in the ServerFlags section. For example, we may wish them to turn off certain things for testing purposes, or they may wish to experiment with settings to attain better performance or stability than they get with the defaults.

A GUI tool makes these settings more accessible to users, which will make Ubuntu's users better able to participate in troubleshooting X problems and in getting the most out of their systems.

Scope

This is not a general purpose "fix broken X" tool. In many cases where setting Options is required to fix X, it's needed because X won't start up at all, and therefore the user isn't in a GUI environment anyway. Thus this spec isn't concerned with providing functionality for selecting the driver, altering monitor settings, and so on.

This is not considered to be a tool that very many users will need to use, and thus is intended to be available only via an "Advanced..." button or the like.

Use Cases

  • Terri wishes to set up a dual-head display on Intrepid, but this requires setting Option "Virtual" "3840 1200" in xorg.conf, which she is not comfortable editing. Instead she uses the X Options Editor to specify it.

  • Sarah reads in a bug report that using Option "VideoKey" "0x01" resolved a problem very similar to hers. She uses X Options Editor to add this option, restarts, and can easily test it out.

  • Leann wishes to report an X bug, but reads that she should enable Option "NoTrapSignals"  "true" first so she collects correct debug info.

  • Kirsten hates how ctrl+alt+backspace exits her system. She shuts it off by toggling the Option "DontZap" "true" option.

Design

The editor's overall architecture will be split into frontend and backend modules, with the idea of sharing the backend with other tools which need to modify xorg.conf. The philosophy is that the fewer chunks of code we have that are modifying xorg.conf, the more consistent the result will be. Also, obviously this allows sharing code maintenance of this part. (As an example, we could use the same parser/writer lib with Jockey and in the installer.)

The GUI editor itself will be composed of a list of xorg.conf sections with options available for modification (e.g. Device and ServerFlags). Selecting a section will display a table of options and their values that the user can modify. On hitting Apply, the xorg.conf will be backed up and modified, and the user prompted to restart X for the changes to take effect.

Phase 1: Foundations + Option "Virtual"

The first portion of the project will focus on a single goal: Providing a mechanism to add "Virtual" option settings to xorg.conf without requiring the user to edit that file directly. Ideally, this should be hooked into the Screen Resolution tool to set the option automatically when the user chooses a dual head layout beyond the limits of the current virtual framebuffer size.

This means the focus will be first on the implementation of the backend xorg.conf parser/writer, not on the GUI editor.

Phase 1 is to be delivered for Intrepid by Alpha 1. Depending on the complexity of its implementation, it may be appropriate to SRU this feature to Hardy as well.

=== Phase 2: GUI Editor

The remainder of the work to implement the GUI will be done in the second phase, and is a much lower priority than phase 1.

Phase 2 is to be delivered by Intrepid+1's feature freeze date. If there is an implementation considered "ready" enough prior to Intrepid's feature freeze, it would be nice to ship it in Intrepid for testing purposes.

Implementation

The backend consists of the following:

  • A simple xorg.conf parser. This could be inspired/derived from Guidance's "xorgconfig", but its API should be made easier for developer use, easier to extend, and easier to maintain.) See https://launchpad.net/xorgparser

  • An xorg.conf writer.
  • An xorg.conf validator. Given an xorg.conf it should perform a sanity-check of the file. The idea is to allow xorg-conf-editing applications to detect if the user's xorg.conf is in a form that can be successfully edited, and to bail out gracefully if not.

  • An options data store. This provides the listing of available options, default values, and so on.

The frontend is a GUI dialog allowing the user to browse the xorg.conf sections that have modifiable options, to modify them, and apply the settings.

Implementation of xorg.conf Parser

[TODO]

Implementation of xorg.conf Writer

[TODO]

Implementation of xorg.conf Validator

[TODO]

Implementation of Options Data Store

The Options Data Store is a collection of options available for each driver and the server. This data should be kept in an easily parsed/written XML format, with the following structure:

  • Option name
  • Option type: none | boolean | number | string
  • Short one sentence description
  • Full description
  • Default value

Much of this data can simply be extracted from the man pages. A script will be implemented to perform this conversion and output the XML data format. If any errors are found in the man pages from this conversion, the fixes need to be forwarded upstream for the appropriate man page.

GTK GUI Frontend

A mockup based on the meeting at the UDS:

attachment:XorgOptionsEditor-gtk.png

NOTE: when boolean or fixed values can be assigned to an option it would be wise to put such options in a combobox instead of a textview.

The GUI frontend will consist of a page showing the current xorg.conf's sections and all available options with their current settings (or their defaults if not set). A visual indicator (such as a checkbox or graying out) should be used to distinguish between options which are listed in xorg.conf vs. those that are not.

An Apply button will back up the current xorg.conf and apply the changes when pressed. Notification should be made that the user needs to reboot.

Qt GUI Frontend

[TODO]

Outstanding Issues

BoF agenda and discussion


CategorySpec