Enabling IP/TCP offload on a NIC that doesn't support it

[LoSfrek]

Hello everyone,
I'm working on a programmable NetFPGA card and what I'm trying to do is checksum offload. The drivers officially don't support this feature, but I'm changing the code on the hardware level so that the card automatically computes checksum for incoming packets and drops the corrupt ones.
Now, what I have to do is somehow tell the kernel not to compute checksum again, since it's already being done by the nic.
The point is, if I try to use ethtool to enable checksum offload, it tells me the nic doesn't support offload.
Well, actually it does, I just don't know how to tell the OS.

Can anybody help me on this? My dream would be a way to force ethtool and enable offload, bypassing the "unsupported" error message.

[Irithori]

Hi,

kernel programming is not my field of expertise.
But fwiw, you might get the answer from looking at the sourcecode of e.g. the intel e1000 kernel module, which does have the tcp offload feature.

Edit: Url
http://sourceforge.net/projects/e1000/?source=directory