[openib-general] [kernel verbs] u64 vs dma_addr_t

[Caitlin Bestler]

openib-general-bounces at openib.org wrote:
> One more question on this topic.
> 
> Why is the ib_sge's addr a u64 and not a dma_addr_t?

Because the hardware may need for it to be a 64 bit
IO Address accessible on the system bus. That applies
to the whole system bus, no matter how many PCI roots
or virtual OSs there are.

In particular there could be a guest OS that was
running in 32-bit mode, and the RDMA hardware receiving
fast path requests will not support different
work request formats for each guest OS.