Re: [virtio-comment] [PATCH 2/2] virtio-net: Clarify the size of the struct virtio_net_hdr for tx

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Fri, 10 Nov 2023 14:40:40 +0200, Parav Pandit <parav@nvidia.com> wrote:
> The feature VIRTIO_NET_F_HASH_REPORT only applies to the receive side.
> However, when VIRTIO_NET_F_HASH_REPORT feature was introduced, it was
> not clarified that the size of the struct virtio_net_hdr on the packet
> transmission also uses higher size when VIRTIO_NET_F_HASH_REPORT is
> negotiated.
>
> Explicitly clarify this.
>
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/183
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> ---
>  device-types/net/description.tex | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/device-types/net/description.tex b/device-types/net/description.tex
> index f5647d4..00ea58d 100644
> --- a/device-types/net/description.tex
> +++ b/device-types/net/description.tex
> @@ -531,6 +531,12 @@ \subsubsection{Packet Transmission}\label{sec:Device Types / Network Device / De
>
>  \drivernormative{\paragraph}{Packet Transmission}{Device Types / Network Device / Device Operation / Packet Transmission}
>
> +If VIRTIO_NET_F_HASH_REPORT is not negotiated, the size of the field
> +\field{struct virtio_net_hdr} is 12 bytes.
> +
> +If VIRTIO_NET_F_HASH_REPORT is negotiated, the size of the field
> +\field{struct virtio_net_hdr} is 20 bytes.
> +

If we need a new feature, because that the implement of the current linux kernel
has the same size on the tx patch.

Thanks.


>  The driver MUST set \field{num_buffers} to zero.
>
>  If VIRTIO_NET_F_CSUM is not negotiated, the driver MUST set
> --
> 2.34.1
>
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