Re: [PATCH bpf-next v2 1/3] net: add priv_flags for allow tx skb without linear

Jason Wang <jasowang@xxxxxxxxxx> · Wed, 20 Jan 2021 11:01:24 +0800

On 2021/1/19 下午5:45, Xuan Zhuo wrote:
In some cases, we hope to construct skb directly based on the existing
memory without copying data. In this case, the page will be placed
directly in the skb, and the linear space of skb is empty. But
unfortunately, many the network card does not support this operation.
For example Mellanox Technologies MT27710 Family [ConnectX-4 Lx] will
get the following error message:

     mlx5_core 0000:3b:00.1 eth1: Error cqe on cqn 0x817, ci 0x8, qn 0x1dbb, opcode 0xd, syndrome 0x1, vendor syndrome 0x68
     00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     00000030: 00 00 00 00 60 10 68 01 0a 00 1d bb 00 0f 9f d2
     WQE DUMP: WQ size 1024 WQ cur size 0, WQE index 0xf, len: 64
     00000000: 00 00 0f 0a 00 1d bb 03 00 00 00 08 00 00 00 00
     00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     00000020: 00 00 00 2b 00 08 00 00 00 00 00 05 9e e3 08 00
     00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
     mlx5_core 0000:3b:00.1 eth1: ERR CQE on SQ: 0x1dbb

So a priv_flag is added here to indicate whether the network card
supports this feature.

I don't see Mellanox engineers are copied. I wonder if we need their 
confirmation on whether it's a bug or hardware limitation.

Thanks