Xvfb (X virtual framebuffer) is an X.Org display server that performs all rendering into virtual memory without any physical display hardware or output. It is the standard way to run GUI applications, take screenshots, and run graphical test suites on headless machines and in CI.

This package builds only the Xvfb DDX from the xorg-server source tree; the Xorg, Xnest and Xephyr servers are disabled so the heavier GPU/DRM stack (libdrm, mesa, udev, libpciaccess, glamor) is not required. It ships libXfont2's compiled-in fonts (fixed, cursor, 6x13), so Xvfb starts without any external font packages, and depends on xkbcomp + xkeyboard-config for keyboard support.

OpenGL note: conda-forge does not ship a runtime software-GL driver, so GLX through Xvfb yields only indirect software rendering on its own. For full OpenGL in a headless environment, render client-side with Mesa, e.g.: * OSMesa: install "mesalib <25.1.0" and set PYOPENGLPLATFORM=osmesa (VTK: VTKDEFAULTOPENGLWINDOW=vtkOSOpenGLRenderWindow). * EGL surfaceless: install libegl + a system Mesa EGL ICD and set EGLPLATFORM=surfaceless, PYOPENGLPLATFORM=egl. * GLX via Xvfb: install system Mesa DRI (swrast/llvmpipe), set DISPLAY=:99, LIBGLALWAYSSOFTWARE=1, GALLIUM_DRIVER=llvmpipe.