Difference between pages "Package:Eselect (OpenGL)" and "Translations:Install/Stage3/7/en"

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{{Ebuild
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=== Installing the Stage 3 tarball ===
|Summary=A Gentoo/Funtoo utility that allows the active OpenGL implementation on a system to be switched between a variety of installed options.
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|CatPkg=app-admin/eselect-opengl
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|Maintainer=
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}}
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== Introduction ==
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Eselect (OpenGL) (also called <tt>eselect-opengl</tt>) is a module for [[Package:Eselect|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 <tt>env.d</tt> file at <tt>/etc/env.d/03opengl</tt> which contains OpenGL settings, as well as managing symbolic links to OpenGL libraries and headers.
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=== Sample env.d File ===
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A sample <tt>env.d</tt> file for a multilib system with xorg-x11 OpenGL implementation may look like this:
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{{file|name=/etc/env.d/03opengl|desc=An example env.d file for eselect-opengl|body=
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# Configuration file for eselect
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# This file has been automatically generated.
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LDPATH="/usr/lib32/opengl/xorg-x11/lib:/usr/lib64/opengl/xorg-x11/lib"
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OPENGL_PROFILE="xorg-x11"
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}}
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== Implementation ==
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Eselect-opengl is implemented as a single bash-based [[Package:Eselect|Eselect]] module approximately 10K in size, installed at <tt>/usr/share/eselect/modules/opengl.eselect</tt>. One interfaces with this module via the main <tt>eselect</tt> command:
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<console>
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# ##i##eselect opengl help
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Manage the OpenGL implementation used by your system
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Usage: eselect opengl <action> <options>
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##g##Standard actions:
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  help                      Display help text
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  usage                    Display usage information
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  version                  Display version information
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##g##Extra actions:
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  list                      List the available OpenGL implementations.
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  set <target>              Select the OpenGL implementation.
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    <target>                  The profile to activate
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    --use-old                If an implementation is already set, use that one instead
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    --prefix=<val>            Set the source prefix (default: /usr)
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    --dst-prefix=<val>        Set the destination prefix (default: /usr)
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    --ignore-missing          Ignore missing files when setting a new implementation
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  show                      Print the current OpenGL implementation.
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</console>
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== What is Switched ==
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Eselect-opengl handles switching of the active:
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* ''Libraries'' (32-bit and 64-bit):
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** libGL
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** libEGL
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** libGLESv1
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** libGLESv2
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* ''C Headers'':
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** <tt>/usr/include/GL/*</tt>
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** <tt>/usr/include/EGL/*</tt>
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** <tt>/usr/include/KHR/*</tt>
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* <tt>libglx.so</tt>
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Ebuilds that provide an active OpenGL implementation install their libraries, headers, etc. in:
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* <tt>/usr/lib/opengl/(implementation-name)/lib</tt>
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* <tt>/usr/lib/opengl/(implementation-name)/include</tt>
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* <tt>/usr/lib/opengl/(implementation-name)/extensions/libglx.so</tt>
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On multilib systems, ebuilds that provide an OpenGL implementation install 32-bit libraries in <tt>/usr/lib32/opengl/(implementation name)/lib</tt> and 64-bit libraries in <tt>/usr/lib64/opengl/(implementation name)/lib</tt>.
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Eselect-opengl looks in these directories for active OpenGL implementations.
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== Criticisms ==
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=== Violation of Build Consistency ===
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As documented in {{Bug|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.
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===== Possible Solutions =====
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A possible solution to this problem, discussed in {{Bug|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.
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The rationale for this design change is that:
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# There should be a consistent and repeatable build/linking process for all OpenGL applications.
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# 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.
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{{EbuildFooter}}
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Latest revision as of 04:42, July 14, 2015

Installing the Stage 3 tarball