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Upcoming Qt switch to OpenGL ES on arm64




Hi all!

The Qt framework can be built either with “desktop” OpenGL, or with OpenGL ES
support. At the moment we are building it with OpenGL ES on armel and armhf,
and with desktop OpenGL on all other architectures.

However we have received a request [1] from two different persons to add arm64
to the list of architectures where OpenGL ES is used.

We want your feedback! If you are using an arm64 device or board with Qt,
please let us know your opinion about this change, by replying to this mail
or to [1], and describe your use case.

So far we are going to make this change starting with the Qt 5.11.3 packages.
In case you already want to test it, the updated qtbase package is available
in experimental [2]. However the reverse dependencies are not yet rebuilt.

This change will affect packages using Qt Gui [3], Qt Widgets [4], Qt Quick
and some other modules. It will not affect packages using the deprecated Qt
OpenGL module because it loads the OpenGL library at runtime.

The best way to check whether some package needs changes is checking Ubuntu
[5], which has been building Qt with OpenGL ES on arm64 since version 16.10
(yakkety) [6].

We will send a new mail with DD-list of packages that we detect to be affected
a bit later.

There are some packages that are not compatible with OpenGL ES. For example,
packages using libglu and Qt simultaneously will most likely have to drop
their arm64 binaries (like they already have no armel or arm64 binaries).
An example of such package is qwtplot3d.

Also note that as this change breaks ABI on arm64, we are renaming libqt5gui5
to libqt5gui5a, which will need binNMUs of all reverse dependencies. The list
of all such dependencies is available here [7]. This will happen together with
the Qt 5.11.3 transition.

Please Cc me or pkg-kde-talk on reply.

[1]: https://bugs.debian.org/881333
[2]: https://tracker.debian.org/news/1004843/
[3]: https://doc.qt.io/qt-5/qtgui-index.html#opengl-and-opengl-es-integration
[4]: https://doc.qt.io/qt-5/qopenglwidget.html
[5]: https://launchpad.net/ubuntu/+source/${SOURCE_PACKAGE_NAME},
     or the “ubuntu patches” link in the right panel of tracker.debian.org
[6]: https://salsa.debian.org/qt-kde-team/qt/qtbase/commit/197063f08928ac9c
[7]: https://perezmeyer.com.ar/ben/qtbase.html

--
Dmitry Shachnev

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