[Xen-devel] Re: Trouble with TCP between domUs

[David Edmondson <dme@xxxxxxx>]

* herbert@xxxxxxxxxxxxxxxxxxx [2006-12-09 01:13:26]
> David Edmondson <dme@xxxxxxx> wrote:
>> The inter-domain protocol has no facility to allow the guest to
>> specify the offset at which the checksum should be placed - how does
>> the peer know where to put it?
>
> When I extended the netback protocol for TSO the idea was that you
> can also have an extra descriptor for checksum offload that would
> carry the offsets.

But that offset is not present today, suggesting that the peer
receiving the packet must be parsing it to determine where to place
the checksum (though I couldn't find that code in a quick inspection).

If the receiver of the packet is required to parse it we're back at
the problem I originally described.

The GSO feature flags are quite specific about what is supported -
checksum feature flags should be the same.

dme.
-- 
David Edmondson, Sun Microsystems, http://www.dme.org


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel