$ LIBGL_ALWAYS_SOFTWARE=1 xeglgears -info -pixmap
EGL_VERSION = 1.4 (DRI2)
GL_RENDERER = Gallium 0.4 on llvmpipe (LLVM 0x300)
GL_VERSION = 2.1 Mesa 8.0.3
GL_VENDOR = VMware, Inc.
there will be no screen update if eglCopyBuffers() is not implemented
 29780 segmentation fault (core dumped)
segfault is in mesa/src/egl/drivers/dri2/egl_dri2.c (dri2_wait_client) since dri2_dpy->flush is NULL.
The same problem happens with xeglgears -pbuffer in dri2_copy_buffers.