[openib-general] SA cache design

[Sean Hefty]

>- It is implemented in kernel mode
>	- while user mode may help during initial debug, it will be important
for
>		kernel mode ULPs such as SRP, IPoIB and SDP to also make use of
>these records

Your kernel footprint is smaller than I expected, which is good.  Note that with
a MAD interface, kernel modules would still have access to any cached data.  I
also wanted to stick with usermode to allow saving the cache to disk, so that it
would be available immediately after a reboot.  (My assumption being that
changes to the network topology would be rare, so we could optimize around a
stable network design.)

As a related topic, there will be a separate SA client interface defined that
will generate SA query MADs for the user.

- Sean