mesa, intel driver, and synchronous flipping

[garrone]

The mesa direct rendering with the intel driver appears to rely on
asychronous flipping. However the hardware, according to the 965
documentation I have downloaded from the intellinuxgraphics site, is
capable of synchronous flips. 

(The kernel file i915_dma.c ors in the "ASYNC_FLIP" constant in the function
i915_dispatch_flip, invoked eventually by a call to glXSwapBuffers.
For a description of the hardware capability, 
refer to volume 1 of the 965 graphics pdf files, searching for the
command MI_DISPLAY_FLIP)

The application I am targeting has dual opengl windows, 
each one running on a separate display, and covering the whole of that
display, from a single Intel graphics chipset.

I wish to:
1) confirm that the xorg software currently does not implement
synchronous flipping for any mode operation,

2) If there is indeed no synchronous flipping, find out what design
limitations with the current codebase are preventing it.

I note that the 965 documentation refers to the use of MI_DISPLAY_FLIP
as a "legacy" operation, and that constructs called flip queues are now
available. However the referenced documentation does not appear to
exist.

Thanks in advance.