[dpdk-users] 答复: How to make virtual NIC (virtio and vmxnet3) support IP header checksum?

[宋捷 <songj@zctt.com>]

Thanks, 

I run testpmd for checking tx_offload capabilities, Virtio do not support IP checksum.

vmxnet3 can't start by testpmd, I need send another email about this.

Thanks
Jie

-----邮件原件-----
发件人: Stephen Hemminger [mailto:stephen@networkplumber.org] 
发送时间: 2019年2月26日 23:48
收件人: 宋捷 <songj@zctt.com>
抄送: 'users' <users@dpdk.org>
主题: Re: [dpdk-users] How to make virtual NIC (virtio and vmxnet3) support IP header checksum?

On Tue, 26 Feb 2019 16:29:00 +0800
宋捷 <songj@zctt.com> wrote:

> Hi All
> 
>     I test the DPDK virtual nics both in Esxi and KVM, I used DPDK  
> vmxnet3, virtio and e1000 nic. I need create IP packets and TX them.
> 
>  
> 
> I set the rte_mbuf as below before TX.
> 
> mb->l2_len = len(out_eth)
> 
> mb->l3_len = len(out_ip)
> 
> mb->ol_flags |= PKT_TX_IPV4 | PKT_TX_IP_CSUM
> 
>  
> 
> It worked well with DPDK virtual e1000 nic, the IP header checksum 
> will be set correct value. but vmxnet3 and virtio just keep 0 for IP 
> header checksum.
> 
> I disable above code and call rte_ipv4_cksum for each IP header 
> checksum. it worked with vmxnet3 and virtio when TX slowly, but 
> checksum invalid once TX quicklyL
> 
>  
> 
> Why the DPDK vmxnet3 and virtio drivers don't support IP checksum?
> 
> If there’s an easy way for adding the IP header checksum with vmxnet3 
> and virtio ?
> 
>  
> 
>  
> 
> Thanks
> 
>  
> 
> Jie
> 

You need to look at the TX_OFFLOAD capability flags in dev_info.
Many drivers do not support IP checksum offload.