why does virtio not support IPv4 CKSUM?

[Stephen Hemminger]

On Thu, 6 Jul 2023 03:47:26 +0000
"jiangheng (G)" <jiangheng14 at huawei.com> wrote:

> Hi 
> 
> why does virtio not support IPv4 CKSUM? But support TCP/UDP cksum.

Because virtio is a software driver developed on Linux and Linux doesn't need/want IP checksum offload.
It takes longer to look at offload bits then to compute checksum in SW.

> 
> If not support ipv4 cksum, when I use GRO, the ip cksum of the packets transmitted to ip layer will be incorrect.
> I have to calculate ip cksum before packet was transmiited to ip layer.
> So why does virtio not support ipv4 cksum ?