From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH] fm10k: fix wrong VLAN value in RX mbuf
Date: Thu, 19 Nov 2015 09:25:47 -0800
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To: Shaopeng He <shaopeng.he@intel.com>
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On Wed, 18 Nov 2015 16:50:09 +0800
Shaopeng He <shaopeng.he@intel.com> wrote:

> VLAN value should be copied from RX descriptor to mbuf,
> this patch fixes this issue.
> 
> Signed-off-by: Shaopeng He <shaopeng.he@intel.com>
> ---
>  drivers/net/fm10k/fm10k_rxtx.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/fm10k/fm10k_rxtx.c b/drivers/net/fm10k/fm10k_rxtx.c
> index 1bac28d..eeb635e 100644
> --- a/drivers/net/fm10k/fm10k_rxtx.c
> +++ b/drivers/net/fm10k/fm10k_rxtx.c
> @@ -146,6 +146,7 @@ fm10k_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
>  #endif
>  
>  		mbuf->hash.rss = desc.d.rss;
> +		mbuf->vlan_tci = desc.w.vlan & FM10K_RXD_VLAN_ID_MASK;
>  
>  		rx_pkts[count] = mbuf;
>  		if (++next_dd == q->nb_desc) {
> @@ -292,6 +293,7 @@ fm10k_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
>  		rx_desc_to_ol_flags(first_seg, &desc);
>  #endif
>  		first_seg->hash.rss = desc.d.rss;
> +		first_seg->vlan_tci = desc.w.vlan & FM10K_RXD_VLAN_ID_MASK;
>  
>  		/* Prefetch data of first segment, if configured to do so. */
>  		rte_packet_prefetch((char *)first_seg->buf_addr +

Good catch, this bug means VLAN's would not work right now.
But I think it isn't quite right.

By masking the VLAN you are losing the received priority bits.
Other drivers like ixgbe preserve the priority bits.