have a DMA bug when buffer address crosses a multiple of the 4GB
boundary(e.g. 4GB, 8GB, 12GB etc). Limit DMA address to be within
4GB address for these controllers. The second DMA bug limits DMA
address to be within 40bit address space. This bug applies to
BCM5714 and BCM5715 and 5708(bce(4) controller). This is not
actually a MAC controller bug but an issue with the embedded PCIe
to PCI-X bridge in the device. So for BCM5714/BCM5715 controllers
also limit the DMA address to be within 40bit address space.
Special thanks to davidch@ who gave me detailed errata information.
I think this change will fix long standing bge(4) instability
issues on systems with more than 4GB memory.
Reviewed by: davidch
f681b29a6d