Re: [PATCH v2 04/13] Connection Manager

On Mon, Dec 04, 2006 at 10:20:51AM -0600, Steve Wise (swise@opengridcomputing.com) wrote:

quoted

 > This and a lot of other changes in this driver definitely says you
 > implement your own stack of protocols on top of infiniband hardware.

...but I do know this driver is for 10-gig ethernet HW.

There is no SW TCP stack in this driver.  The HW supports RDMA over
TCP/IP/10GbE in HW and this is required for zero-copy RDMA over Ethernet
(aka iWARP).  The device is a 10 GbE device, not Infiniband.  The
Ethernet driver, upon which the rdma driver depends, acts both like a
traditional Ethernet NIC for the Linux stack as well as a TCP offload
device for the RDMA driver allowing establishment of RDMA connections.
The Connection Manager (patch 04/13) sends/receives messages from the
Ethernet driver that sets up HW TCP connections for doing RDMA.  While
this is indeed implementing TCP offload, it is _not_ integrating it with
the sockets layer nor the linux stack and offloading sockets
connections.  Its only supporting offload connections for the RDMA
driver to do iWARP.   The Ammasso device is another example of this
(drivers/infiniband/hw/amso1100).  Deep iSCSI adapters are another
example of this.

So what will happen when application will create a socket, bind it to
that NIC, and then try to establish a TCP connection? How NIC will
decide that received packets are from socket but not for internal TCP
state machine handled by that device?

As a side note, does all iwarp devices _require_ to have very
limited TCP engine implemented it in its hardware, or it is possible
to work with external SW stack?
 

Steve.

-- 
	Evgeniy Polyakov