[PATCH v6 09/13] net/pcap: support VLAN insert and strip

Stephen Hemminger
2026-01-25T19:24:06Z

Driver can easily insert VLAN tag strip and insertion similar
to how it is handled in virtio and af_packet.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
doc/guides/nics/features/pcap.ini | 1 +
doc/guides/rel_notes/release_26_03.rst | 1 +
drivers/net/pcap/pcap_ethdev.c | 30 ++++++++++++++++++++++++--
3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/doc/guides/nics/features/pcap.ini b/doc/guides/nics/features/pcap.ini
index d2f5ee6039..7043213c5f 100644
--- a/doc/guides/nics/features/pcap.ini
+++ b/doc/guides/nics/features/pcap.ini
@@ -10,6 +10,7 @@ Scattered Rx = Y
Timestamp offload = Y
Basic stats = Y
Stats per queue = Y
+VLAN offload = Y
Multiprocess aware = Y
FreeBSD = Y
Linux = Y
diff --git a/doc/guides/rel_notes/release_26_03.rst b/doc/guides/rel_notes/release_26_03.rst
index 41f96ad1af..4e31d85e50 100644
--- a/doc/guides/rel_notes/release_26_03.rst
+++ b/doc/guides/rel_notes/release_26_03.rst
@@ -58,6 +58,7 @@ New Features
* **Updated PCAP ethernet driver.**

* Added support for setting MTU in single interface mode.
+ * Added support for VLAN insertion and stripping.
* Changed transmit burst to always return the number of packets requested.
Failed sends are counted as transmit errors.

diff --git a/drivers/net/pcap/pcap_ethdev.c b/drivers/net/pcap/pcap_ethdev.c
index 9ebb9c8633..85225fca2d 100644
--- a/drivers/net/pcap/pcap_ethdev.c
+++ b/drivers/net/pcap/pcap_ethdev.c
@@ -76,6 +76,7 @@ struct queue_missed_stat {
struct pcap_rx_queue {
uint16_t port_id;
uint16_t queue_id;
+ bool vlan_strip;
struct rte_mempool *mb_pool;
struct queue_stat rx_stat;
struct queue_missed_stat missed_stat;
@@ -103,6 +104,7 @@ struct pmd_internals {
bool single_iface;
bool phy_mac;
bool infinite_rx;
+ bool vlan_strip;
};

struct pmd_process_private {
@@ -333,6 +335,10 @@ eth_pcap_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
}

mbuf->pkt_len = len;
+
+ if (pcap_q->vlan_strip)
+ rte_vlan_strip(mbuf);
+
uint64_t us = (uint64_t)header->ts.tv_sec * US_PER_S + header->ts.tv_usec;

*RTE_MBUF_DYNFIELD(mbuf, timestamp_dynfield_offset, rte_mbuf_timestamp_t *) = us;
@@ -421,6 +427,12 @@ eth_pcap_tx_dumper(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
void *temp = NULL;
const uint8_t *data;

+ if (mbuf->ol_flags & RTE_MBUF_F_TX_VLAN) {
+ /* if vlan insert fails treat it as error */
+ if (unlikely(rte_vlan_insert(&mbuf) != 0))
+ continue;
+ }
+
calculate_timestamp(&header.ts);
header.len = len;
header.caplen = len;
@@ -498,6 +510,12 @@ eth_pcap_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
void *temp = NULL;
const uint8_t *data;

+ if (mbuf->ol_flags & RTE_MBUF_F_TX_VLAN) {
+ /* if vlan insert fails treat it as error */
+ if (unlikely(rte_vlan_insert(&mbuf) != 0))
+ continue;
+ }
+
data = pcap_pktmbuf_read(mbuf, 0, len, &temp);
if (likely(data != NULL &&
pcap_sendpacket(pcap, data, len) == 0)) {
@@ -732,8 +750,13 @@ eth_dev_stop(struct rte_eth_dev *dev)
}

static int
-eth_dev_configure(struct rte_eth_dev *dev __rte_unused)
+eth_dev_configure(struct rte_eth_dev *dev)
{
+ struct pmd_internals *internals = dev->data->dev_private;
+ struct rte_eth_conf *dev_conf = &dev->data->dev_conf;
+ const struct rte_eth_rxmode *rxmode = &dev_conf->rxmode;
+
+ internals->vlan_strip = !!(rxmode->offloads & RTE_ETH_RX_OFFLOAD_VLAN_STRIP);
return 0;
}

@@ -751,7 +774,9 @@ eth_dev_info(struct rte_eth_dev *dev,
dev_info->min_rx_bufsize = 0;
dev_info->min_mtu = RTE_ETHER_MIN_LEN - RTE_ETHER_HDR_LEN - RTE_ETHER_CRC_LEN;
dev_info->max_mtu = RTE_ETH_PCAP_SNAPLEN;
- dev_info->tx_offload_capa = RTE_ETH_TX_OFFLOAD_MULTI_SEGS;
+ dev_info->tx_offload_capa = RTE_ETH_TX_OFFLOAD_MULTI_SEGS |
+ RTE_ETH_TX_OFFLOAD_VLAN_INSERT;
+ dev_info->rx_offload_capa = RTE_ETH_RX_OFFLOAD_VLAN_STRIP;

return 0;
}
@@ -898,6 +923,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
pcap_q->mb_pool = mb_pool;
pcap_q->port_id = dev->data->port_id;
pcap_q->queue_id = rx_queue_id;
+ pcap_q->vlan_strip = internals->vlan_strip;
dev->data->rx_queues[rx_queue_id] = pcap_q;

if (internals->infinite_rx) {
--
2.51.0