There is a discussion over openqnx.com about going over the 4Gig limit and its implication on driver using DMA.

My take is that the OS should not provide contiguous memory above 4Gig unless specifically requested/allowed by the 
driver.  I base my statement on being able to provide backward compatibility with existing user driver.

It's being proposed that to provide backward compatibility that memory partitioning be used, but my counter argument is 
that this is a 6.4 feature. 
Plus it might might be an expensive add-on. Lastly it seems to me like it's the kind of thing that would is easy to 
configure improperly.  

How is that managed for 6.3. ( I believe 4Gig support was broken in 6.3.2 right?)

What do the Gurus have to say about this?

4Gig will probably be the "norm" in 1 year from now and it should be as easy as sticking ram in the machine.