Brief description of some debug options:

Tips: 
  - enable the "magic-sysreq" thing in kernel-config to be able to
    shut down your computer gracefully if anything really bad happens...
  - or have terminal/second computer hooked up to kill processes or
    shutdown the machine.
  - can debug glx.so when you compile the module with "-g" (no need to
    recompile Xserver) and start server in gdb - need to to that from 
    a remote terminal. (Configure glx with --enable-debug)
  - Remember that the mga driver will cause (and trap) segfaults if the
    X server is trying to do 2d operations while a 3d application is
    active. Such a segfault is nothing to be alarmed by. They can be
    recognized by the fact that they were trying to write to an address
    in the following range: [MGAMMIOBase, MGAMMIOBase+0x3000]
    See servGL/hwglx/mga/mgadma.c, RegisterAccessSignalHandler for a
    good breakpoint position. (Or you could just set a breakpoint at
    FatalError());

Disable HW driver:
  - you can disable HW rendering to test is everything else works well
  - disable HW with setting "nohw = 1" in the configuration file

GLX log: 
  - server side logging of OpenGL calls
  - have to compile with "-DGLX_LOG"
  - enable with "debug = 1" in the configuration file 
     where x is the loglevel
      0 = LOG_ALWAYS
      1 = LOG_TRACE
      2 = LOG_ARGS
      3 = LOG_DATA
  - output goes to /var/log/glx_debug.log

MGA log:
  - driver specific logging
  - have to compile with "DriverLogging" defined
  - set log filename with "mga_logfile=filename" in the configuration file
    (if not set log goes to Xserver's stdout)
  - set log level with "mga_loglevel=x" in the configuration file 
      where x is the loglevel
	0            => log only error messages.
	1 or not set => error + standard debugging messages
	>1           => more messages

MGA performance boxes:
  - colored boxes in upper left corner of GL window.
  - enable with "mga_boxes=1" in the configuration file 
  - no boxes:  SW rendering.
  - white box: HW rendering.
      this first box will be grey in psuedo-dma mode,
      purple when using direct rendering
  - red box: had to wait for drawing to complete for some reason.
  - blue box:   the X server forced a sync by touching a register
  - yellow box: textures were swapped
  - green box:  had to wait for HW to finish frame (100% card utilization).
  - The bar below the boxes represents utilization of primary and
    secondary DMA buffers. If one of these overflowed it will be rendered as a
    solid bar.

Software fallback:
  - software fallback for unsupported paths can be disabled
  - set this behavior with "mga_nofallback=1" in the configuration file
  - silently renders with the closest supported primative

