Eselect (OpenGL)

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app-admin/eselect-opengl


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Summary: A Gentoo/Funtoo utility that allows the active OpenGL implementation on a system to be switched between a variety of installed options.


News

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IP Space Migration Continues

All Funtoo user containers in the 8.28 IP space will be moving into our new IP space (172.97) over the next few days. If you have DNS set up -- be sure to watch your container and update to the new IP! container.host.funtoo.org DNS will be updated after the move.
2015-08-27 by Drobbins
Drobbins

Funtoo Hosting IP Move

Funtoo user containers with IPs in the 72.18.x.x range will be gradually migrating to new IP addresses this week. If you have DNS entries for your containers, please be aware that your DNS will need to be updated.
2015-08-11 by Drobbins
Drobbins

New ARM Stages

New ARM Stages, built with a new toolchain, are now hitting mirrors. Existing ARM users should re-install using these stages (dated Aug 3, 2015 or later,) rather than upgrade using emerge.
2015-08-06 by Drobbins
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Eselect (OpenGL)

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Introduction

Eselect (OpenGL) (also called eselect-opengl) is a module for Eselect that allows the OpenGL implementation on a Funtoo Linux or Gentoo Linux system to be switched between a variety of installed OpenGL implementations. It functions by creating an env,d file at /etc/env.d/03opengl which contains OpenGL settings. A sample env.d file for a multilib system with xorg-x11 OpenGL implementation may look like this:

/etc/env.d/03opengl - An example env.d file for eselect-opengl
# Configuration file for eselect
# This file has been automatically generated.
LDPATH="/usr/lib32/opengl/xorg-x11/lib:/usr/lib64/opengl/xorg-x11/lib"
OPENGL_PROFILE="xorg-x11"

Implementation

Eselect-opengl is implemented as a single bash-based Eselect module approximately 10K in size, installed at /usr/share/eselect/modules/opengl.eselect. One interfaces with this module via the main eselect command:

# eselect opengl help
Manage the OpenGL implementation used by your system
Usage: eselect opengl <action> <options>

Standard actions:
  help                      Display help text
  usage                     Display usage information
  version                   Display version information

Extra actions:
  list                      List the available OpenGL implementations.
  set <target>              Select the OpenGL implementation.
    <target>                  The profile to activate
    --use-old                 If an implementation is already set, use that one instead
    --prefix=<val>            Set the source prefix (default: /usr)
    --dst-prefix=<val>        Set the destination prefix (default: /usr)
    --ignore-missing          Ignore missing files when setting a new implementation
  show                      Print the current OpenGL implementation.

What is Switched

Eselect-opengl handles switching of the active:

  • Libraries (32-bit and 64-bit):
    • libGL
    • libEGL
    • libGLESv1
    • libGLESv2
  • C Headers:
    • /usr/include/GL/*
    • /usr/include/EGL/*
    • /usr/include/KHR/*

Ebuilds that provide an active OpenGL implementation install their libraries and headers in:

  • /usr/lib/opengl/(implementation-name)/lib
  • /usr/lib/opengl/(implementation-name)/include

On multilib systems, 32-bit libraries are installed to /usr/lib32/opengl/(implementation name)/lib and 64-bit libraries are installed to /usr/lib64/opengl/(implementation name)/lib.

Eselect-opengl looks in these directories for active OpenGL implementations.

Criticisms

Violation of Build Consistency

As documented in FL-1309, sometimes packages fail to merge when the "wrong" eselect opengl implementation is selected. This violates Portage's ability to consistently build a package from source, assuming all its dependencies are satisfied. This could be classified as a design bug -- eselect-opengl is functioning as intended, but its underlying theory of operation is not correct.

Possible Solutions

A possible solution to this problem, discussed in FL-1309, is to redesign eselect-opengl to only select the runtime OpenGL implementation, but to have all ebuilds build against the official xorg-x11 OpenGL implementation.

The rationale for this design change is that:

  1. There should be a consistent and repeatable build/linking process for all OpenGL applications.
  2. AMD and NVIDIA implementations of OpenGL are designed to be more of a "drop-in" runtime replacement for xorg-x11, rather than a standalone replacement for xorg-x11, and thus appear to exhibit more build-time bugs.