[openib-general] MTHCA features

[Roland Dreier]

    James> It is my understanding that the current MTHCA driver does
    James> not support InfiniBand memory windows or memory
    James> registration using virtual addresses.

    James> Is this information correct? If so, when will these
    James> features be supported?

Well, memory registration is pretty complete.  By design, we only
support memory registration with physical addresses for kernel
consumers even at the verbs API level (ie there are no mthca-specific
limitations).  In the kernel, registration by virtual address is not
very useful.  For userspace verbs, only registration by virtual
address is supported for obvious reasons.

Memory windows are not implemented for mthca.  It wouldn't be a lot of
work for someone with access to Mellanox documentation to implement
them, but they're not particularly useful due to their performance
characteristics.

 - R.