Summary:
This is the initial implementation of a DRM backend based on the EGLDevice,
EGLOutput, and EGLStream extensions, supporting NVIDIA graphics hardware using
their proprietary driver. The new backend will be used if the environment
variable KWIN_DRM_USE_EGL_STREAMS is set. On initialization, it will attempt to
create an EGLDevice based on the DRM device currently in use and create
EGLOutputs and EGLStreams for any attached displays. These are used to control
presentation of the final composited frame. Additionally, it will register the
wl_eglstream_controller Wayland interface so that native EGL windows created by
clients can be attached to an EGLStream allowing buffer contents to be shared
with the compositor as a GL texture.
At this time there are two known bugs in the NVIDIA driver's EGL implementation
affecting desktop functionality. The first can result in tooltip windows drawn
by plasmashell to contain incorrect contents. The second prevents KWayland from
being able to query the format of EGLStream-backed buffers which interferes
with the blur effect. Fixes for both of these are currently in development and
should appear in an upcoming NVIDIA driver release.
Additionally, hardware cursors are currently not supported with this backend.
Enabling them causes the desktop to intermittently hang for several seconds.
This is also likely a bug in the NVIDIA DRM-KMS implementation but the root
cause is still under investigation.
Test Plan:
On a system with an NVIDIA graphics card running a recent release of their
proprietary driver
* Ensure the nvidia_drm kernel module is loaded with the option "modeset=1"
("# cat /sys/module/nvidia_drm/parameters/modeset" should print "Y")
* Ensure EGL external platform support is installed
https://github.com/NVIDIA/eglexternalplatform
* Ensure KWin was build with the CMake option
KWIN_BUILD_EGL_STREAM_BACKEND=ON (this is the default)
* Start a plasma wayland session with the environment variable
KWIN_DRM_USE_EGL_STREAMS set
* Ensure output from KWin OpenGL initialization indicates the NVIDIA EGL
driver is in use (as opposed to Mesa / llvmpipe).
* Desktop should be fully functional and perform smoothly.
Reviewers: #kwin, romangg, davidedmundson
Reviewed By: #kwin, romangg, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D18570
KWin is an easy to use, but flexible, composited Window Manager for Xorg windowing systems (Wayland, X11) on Linux. Its primary usage is in conjunction with a Desktop Shell (e.g. KDE Plasma Desktop). KWin is designed to go out of the way; users should not notice that they use a window manager at all. Nevertheless KWin provides a steep learning curve for advanced features, which are available, if they do not conflict with the primary mission. KWin does not have a dedicated targeted user group, but follows the targeted user group of the Desktop Shell using KWin as it's window manager.
KWin is not...
a standalone window manager (c.f. openbox, i3) and does not provide any functionality belonging to a Desktop Shell.
a replacement for window managers designed for use with a specific Desktop Shell (e.g. GNOME Shell)
a minimalistic window manager
designed for use without compositing or for X11 network transparency, though both are possible.
If you are an application developer having questions regarding windowing systems (either X11 or Wayland) please do not hesitate to contact us. Preferable through our mailing list. Ideally subscribe to the mailing list, so that your mail doesn't get stuck in the moderation queue.
End user
Please contact the support channels of your Linux distribution for user support. The KWin development team does not provide end user support.
Please refer to hacking documentation for how to build and start KWin. Further information about KWin's test suite can be found in TESTING.md.
Guidelines for new features
A new Feature can only be added to KWin if:
it does not violate the primary missions as stated at the start of this document
it does not introduce instabilities
it is maintained, that is bugs are fixed in a timely manner (second next minor release) if it is not a corner case.
it works together with all existing features
it supports both single and multi screen (xrandr)
it adds a significant advantage
it is feature complete, that is supports at least all useful features from competitive implementations
it is not a special case for a small user group
it does not increase code complexity significantly
it does not affect KWin's license (GPLv2+)
All new added features are under probation, that is if any of the non-functional requirements as listed above do not hold true in the next two feature releases, the added feature will be removed again.
The same non functional requirements hold true for any kind of plugins (effects, scripts, etc.). It is suggested to use scripted plugins and distribute them separately.
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