[ofa-general] [PATCHv2] IB/ipoib: S/G and HW checksum support

[James Lentini]

On Tue, 4 Sep 2007, Michael S. Tsirkin wrote:

> Add module option hw_csum: when set, IPoIB will report S/G
> support, and rely on hardware end-to-end transport checksum (ICRC)
> instead of software-level protocol checksums.

The purpose of this option would be clearer if the parameter name were 
"omit_csum". Calling this "HW checksum" support is misleading because 
the term is already used to describe network adapters that calculate 
TCP/IP checksums in hardware. I realize that you are using the HW 
checksum infrastructure to implement this, but it is really not the 
same thing.

> Since this will not inter-operate with older IPoIB modules, this 
> option is off by default.
> 
> Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>

Does the S/G support need to be tied to the checksum changes?

Will the proposed IPoIB wire format changes be standardized in the 
IETF?

Can you describe what will happened when an IETF compliant IPoIB node 
and a "csum omitted" IPoIB node attempt to communicate? How would the 
interoperability errors be indicated to the user?