On Thu, May 19, 2011 at 8:41 PM, Jason Gunthorpe
[off-list ref] wrote:

This is why in the IB verbs architecture nearly everything is tied to
a *device*, not a port.

LIO has a feature called "access control lists" that allows to define
which initiators are allowed to log in to a target. For a single-rail
HCA it makes most sense to configure that information per HCA. For a
dual-rail HCA the most flexible approach is to allow the user to
configure ACLs per HCA port. That made me wonder whether it is
possible to find out from software whether a dual-port HCA is
single-rail or dual-rail. A quick glance at struct ib_device_attr and
struct ib_port_attr in <rdma/ib_verbs.h> didn't yield any field usable
for this purpose. Did I overlook something ?

Bart.