Re: [PATCH v3 01/28] IB/Verbs: Implement new callback query_transport()

["ira.weiny" <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Wed, Apr 15, 2015 at 01:29:31PM -0600, Hefty, Sean wrote:
> > libibverbs also exposes transport at the device level. Isn't a change to
> > make transport per port rather than per device needed there as well to
> > be consistent with these proposed kernel changes ? If so, would the
> > additional IBoE transport be exposed ? We also need to worry about
> > backward compatibility for existing applications.
> 
> Libibverbs probably can't change without bumping the major version number.  If the kernel attribute structures change, this is probably something that the user_verbs module would need to handle to avoid breaking the ABI.
>

Transport is not directly sent thought the kernel ABI.  It is fabricated when
the HCA provider driver is loaded.

static struct ibv_device *try_driver(struct ibv_driver *driver,
                                     struct ibv_sysfs_dev *sysfs_dev)
{
...
        switch (dev->node_type) {
        case IBV_NODE_CA:
        case IBV_NODE_SWITCH:
        case IBV_NODE_ROUTER:
                dev->transport_type = IBV_TRANSPORT_IB;
                break;
        case IBV_NODE_RNIC:
                dev->transport_type = IBV_TRANSPORT_IWARP;
                break;
        case IBV_NODE_USNIC:
                dev->transport_type = IBV_TRANSPORT_USNIC;
                break;
        case IBV_NODE_USNIC_UDP:
                dev->transport_type = IBV_TRANSPORT_USNIC_UDP;
                break;
        default:
                dev->transport_type = IBV_TRANSPORT_UNKNOWN;
                break;
        }
...
}

I'm not sure how to fix this once we get to the user space problem.  But I
don't think it affects this set of patches.

Ira

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