On Tue, 2006-12-05 at 18:59 +0300, Evgeniy Polyakov wrote: > On Tue, Dec 05, 2006 at 09:39:58AM -0600, Steve Wise ([EMAIL PROTECTED]) > wrote: > > > Phrases like "MPA-aware TCP" rises a lot of questions - briefly saying > > > that hardware (even if it is called ethernet driver) can create and work > > > with own TCP flows potentially modified in the way it likes which is seen > > > in driver. Likely such flows will not be seen by upper layers like OS > > > network stack according to hardware descriptions. > > > > > > Is it correct? > > > > > > > I don't quite get your point about the driver aspect of this? > > > > The HW manages the iWARP connection including data flow. It adheres to > > the MPA, RDDP, and RDMAP protocol specification IDs from the IETF. The > > HW manages how data gets pushed out in the RDMA stream. The RDMA > > Driver just requests a TCP connection and does the MPA exchange. Then > > tells the hardware to move the connection into RDMA mode. From that > > point on, the driver simply suffles IO work requests from the consumer > > application to the hardware and handles asynchronous events while the > > connection is up and running. > > My main concern about this is the fact, that protocol handling is > splitted into SF and HW parts, and actually until negotiation is > completed those parts are completely unrelated to each other, so > requested TCP connection can leak into main stack and main stack can > send some packets which can be considered as MPA negotiation. >
Ah. Data from an offloaded connection cannot leak into the main stack nor vice-verse. We can take an active RDMA connection establishment as an example if you want: Once the message is sent to the HW to "setup a TCP connection from addr/port a.b to addr/port c.d", then packets on that connection (that 4-tuple) will always be delivered to the RDMA driver, not the native stack. If the the packet received after the connection is setup is -not- an MPA reply (in this example), then the connection is aborted. Once the connection is aborted. So no leaking can happen. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
