I've implemented a network driver that uses PCIe shared memory for the physical layer to support network communication 
over the PCIe bus between multiple CPUs.  Since this is a 'reliable' physical layer I would like to disable packet 
checksums to improve performance. 

I can see that it's possible to enable hardware offload of Tx/Rx checksums but does anyone know if it can be completely 
disabled -- don't generate and don't check checksums.