[PATCH v2 3/3] net/af_packet: support jumbo frames

[Xavier Guillaume]

Derive max_rx_pktlen and max_mtu from the actual TPACKET ring
frame size rather than the static RTE_ETHER_MAX_LEN (1518).
This allows jumbo frame support when the user specifies a
larger framesz devarg at vdev creation time, for example:

  --vdev=net_af_packet0,iface=eth0,framesz=9216

The advertised capabilities now accurately reflect what the
configured ring can handle, avoiding both false limitations
with large frames and false promises with small ones.

Signed-off-by: Xavier Guillaume <xavier.guillaume at ovhcloud.com>
---
 drivers/net/af_packet/rte_eth_af_packet.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
index b04987aaf7..bfd2693a69 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -402,7 +402,10 @@ eth_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
 
 	dev_info->if_index = internals->if_index;
 	dev_info->max_mac_addrs = 1;
-	dev_info->max_rx_pktlen = RTE_ETHER_MAX_LEN;
+	dev_info->max_rx_pktlen = internals->req.tp_frame_size -
+		TPACKET2_HDRLEN + sizeof(struct sockaddr_ll);
+	dev_info->max_mtu = dev_info->max_rx_pktlen -
+		RTE_ETHER_HDR_LEN - RTE_ETHER_CRC_LEN;
 	dev_info->max_rx_queues = (uint16_t)internals->nb_queues;
 	dev_info->max_tx_queues = (uint16_t)internals->nb_queues;
 	dev_info->min_rx_bufsize = 0;
-- 
2.34.1