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<h2 class="title"><a name="gbm" id=
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<h3>Overview</h3>
<p>GBM is a memory allocation API developed as a component of the
Mesa project. Most Wayland compositors use the GBM API to
initialize an EGLDisplay object directly on a GPU, and to allocate
the EGLSurface representing the desktop. The NVIDIA driver includes
a GBM backend enabling the use of such software on NVIDIA GPUs. A
GBM EGL external platform library is also included to enable the
use of GBM objects in EGL.</p>
<h3>Requirements</h3>
<p>The following are necessary to enable use of the NVIDIA driver's
GBM backend and its EGL and related Wayland client support:</p>
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<p>DRM KMS must be enabled. See <a href="kms.html" title=
"Chapter 36. Direct Rendering Manager Kernel Modesetting (DRM KMS)">
Chapter 36, <i>Direct Rendering Manager Kernel Modesetting
(DRM KMS)</i></a> for details.</p>
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<p>libgbm.so.1 from Mesa version 21.2 (<a href=
"https://gitlab.freedesktop.org/mesa/mesa" target=
"_top">https://gitlab.freedesktop.org/mesa/mesa</a>).</p>
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<li>
<p>egl-wayland version 1.1.8 or later must be present (if installed
separately from the the NVIDIA driver). To support applications
that use the wl_drm Wayland protocol to select a GPU to render on,
such as Xwayland, version 1.1.9 or later must be present.</p>
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<h3>Xwayland and GBM</h3>
<p>Xwayland uses the GLAMOR backend to accelerate X application
rendering using EGL. While not required for basic functionality,
GLAMOR acceleration is required for good performance when running
accelerated Vulkan or OpenGL X11 applications. The GLAMOR
integration code in Xwayland has paths to use either EGLStreams or
GBM to allocate surfaces for use with accelerated rendering. To use
the GBM path with the NVIDIA driver's GBM backend and GBM EGL
external platform library, the installed copy of Xwayland should be
a build from the master branch of <a href=
"https://gitlab.freedesktop.org/xorg/xserver" target=
"_top">https://gitlab.freedesktop.org/xorg/xserver</a> at least as
recent as commit 5daf42b4. Xwayland versions 21.1.3 and above
satisfy this requirement.</p>
<p>See <a href="xwayland.html" title=
"Chapter 40. OpenGL, Vulkan and VDPAU on Xwayland">Chapter 40,
<i>OpenGL, Vulkan and VDPAU on Xwayland</i></a> for more details on
Xwayland support in the NVIDIA driver.</p>
<h3>Logging/Tracing</h3>
<p>The NVIDIA GBM backend supports logging information about its
behavior and the reasons for various function call failures to
stderr. Such information may be useful for developers debugging
applications or end users diagnosing system behavior issues. Set
the environment variable '__NV_GBM_TRACE_ENABLED' to a non-zero
integer value to enable this logging.</p>
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