Hello everyone,
I'm working on a NetFPGA card, and what I'm currently trying to do is, amongst other things, checksum offload.
The code itself is quite simple, the point is I need to test it now... And the card does not support checksum offload by itself, so I can't just use ethtool.
Is there a way to "force" Linux not to perform checksum, since I already do it in hardware?
Or maybe the checksum is performed at driver level, so I should try to modify the card drivers?

Thanks in advance!

If the card has no means to do checksum then the ONLY choice is to let the normal OS do it. You can't change that. It either has to be calculated on the nic or use the cpu to compute it.

Go out and get a quality NIC and one that has OEM linux support. I have found the Intel Pro line some of the good ones.

I find it almost impossible to believe that this device doesn't support the most common advanced features.

Over the years I have seen a few deals like that. A single card you buy once and use anywhere for almost any connection. Never seems to have caught on.

It seems I've not made myself clear, I'm sorry.
I'm working on a project that aims to implement on a netFPGA card a NIC with checksum offload features (and others). I'm starting from the built-in NIC reference project, but I work on hardware only, so I'll not touch the drivers (I'm very short on time for my work!)
The problem is the OS won't know the nic can do checksum offload (on incoming packets). So what I'm asking is a way to deactivate the OS checksum, since I already do it in hardware, but I can't tell him!
I hope it's clearer now

OH.

I think then we need to investigate how a normal nic using offload tells the os that the checksum is OK.

On a normal system a nic that uses checksum, I think sends over a dummy number. The OS even knows it is a bad checksum on every packet. That is the case on say wireshark. But the OS never seems to care.

You not need to to anything.

The best place to ask might be the designers of the board. The many have seen this issue already.