[ofw] API breakage in trunk

[Sean Hefty]

> > > I don't see any reason why ib_ca_attr_t can't just be extended ...
>One can do it.
>It doesn't break backward compatability, so old applications will work well
>with new kernel (i.e. with extended ib_ca_attr_t).
>But new applications, running against old kernel,  may crash.

Maybe it's time to separate the user space APIs from the user to kernel
interfaces from the kernel APIs.

>> >	// for LLE
>> >	enum rdma_transport_type[MAX_PORT_NUM]	transport;
>> >
>> >	// for vendor specific info
>> >	enum vendor_info_type		vendor_info;
>> >	union {
>> >		uplink_info_t		mlnx_vendor_info;
>> // for
>> >Mellanox
>> >	};

We could add new calls to obtain vendor specific data.  Although the transport
type ideally belongs as a common attribute.  The Linux solution to the problem
was to make use of padding in the structure, which you suggested as the 'third'
solution.  That may be the cleanest way to add new fields to the structure