"Reaching this milestone can be attributed to Red Hat, Google's
Chrome/Chromium OS developers, and others working on the Mesa /
Gallium3D software stack. Just recently LLVMpipe gained support for
GLX_EXT_texture_from_pixmap, the GLX extension that's required by
many Linux compositing window managers. These improvements allow
the desktop effects to all be done on the CPU without any
dependence on any GPU hardware driver. GNOME Shell on the VESA
driver or within a KVM/QEMU guest is fair game.