[ofa-general] RE: new API for the rdma-cma

[Steve Wise]

Jason Gunthorpe wrote:
> On Wed, Jan 16, 2008 at 09:33:22AM -0600, Steve Wise wrote:
> 
>> Regardless, I don't see any way to know which if_index (or even if_name) 
>> maps to which port on a multi-port rdma device.  The /sys/class/.../net:*
>> entries show both port device if_names, but there is really no way
>> to know
> 
> Well, I suppose no matter what you do, you have to start there :)
> Isn't this information available through sysfs?
> 
> It looks pretty easy to find out which ipoib devices are on the same
> PCI device through sysfs, but I don't immediately see a way to get the
> port number it is bound too (this should probably be added..)
> 
>> which one is port 1 and which one is port 2. With interface renaming, it is 
>> not necessarily true, for example, given an rnic with 2 ports setup as eth1 
>> and eth2, that eth1 maps to port 1 of a device and eth2 maps to port 2.
>> They could be renamed to anything. Does if_index remain constant?
>> IE maybe
> 
> if_index is constant once the device is created until it is
> destroyed. Renames do not affect if_index. I suppose it is possible
> that with enough device creation/destruction if_index will wrap, and
> then it won't have port1 < port2 anymore..
> 
> Jason

Perhaps the best way is to add a new sysfs entry that makes it explicit 
which if_index maps to which rdma device port.  Or maybe add if_index to 
the ibv_port_attr structure...

Steve.