Re: [PATCH v3 1/3] net/iavf: support LLDP Tx via mbuf ptype or dynfield

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Apr 17, 2026 at 10:08:02AM +0000, Ciara Loftus wrote:
> Previously, the only way to transmit LLDP packets via the iavf PMD
> was to register the IAVF_TX_LLDP_DYNFIELD dynamic mbuf field and set
> it to a non-zero value on each LLDP mbuf before Tx.
> 
> This patch adds an alternative. If the new devarg `enable_ptype_lldp` is
> set to 1, and if the mbuf packet type is set to RTE_PTYPE_L2_ETHER_LLDP
> then a Tx path with context descriptor support will be selected and any
> packets with the LLDP ptype will be transmitted.
> 
> The dynamic mbuf field support is still present however it is intended
> that it will be removed in a future release, at which point only the
> packet type approach will be supported.
> 
> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> ---
> v3:
> * Enable ptype LLDP via new devarg
> ---

Some feedback around documentation inline below.

/Bruce

>  doc/guides/nics/intel_vf.rst           | 21 ++++++++++++++++-----
>  doc/guides/rel_notes/release_26_07.rst |  5 +++++
>  drivers/net/intel/iavf/iavf.h          |  1 +
>  drivers/net/intel/iavf/iavf_ethdev.c   | 15 +++++++++++++++
>  drivers/net/intel/iavf/iavf_rxtx.c     |  2 +-
>  drivers/net/intel/iavf/iavf_rxtx.h     |  9 +++++----
>  6 files changed, 43 insertions(+), 10 deletions(-)
> 
> diff --git a/doc/guides/nics/intel_vf.rst b/doc/guides/nics/intel_vf.rst
> index 5fa2ddc9ea..4b65fa50cc 100644
> --- a/doc/guides/nics/intel_vf.rst
> +++ b/doc/guides/nics/intel_vf.rst
> @@ -675,12 +675,14 @@ Inline IPsec Support
>  Diagnostic Utilities
>  --------------------
>  
> -Register mbuf dynfield to test Tx LLDP
> -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +Tx LLDP Testing
> +~~~~~~~~~~~~~~~
>  
> -Register an mbuf dynfield ``IAVF_TX_LLDP_DYNFIELD`` on ``dev_start``
> -to indicate the need to send LLDP packet.
> -This dynfield needs to be set to 1 when preparing packet.
> +There are two methods to trigger LLDP packet transmission from the VF.
> +
> +The first method is to register an mbuf dynfield ``IAVF_TX_LLDP_DYNFIELD`` before
> +``dev_start``. This dynfield needs to be set to 1 when preparing an LLDP packet
> +intended for transmission.
>  

Switch the order of the methods in the docs. We should always start with
the best/recommended method first, so the user doesn't have to read through
the less-recommended methods in order to get to the best one.

Also not when describing the dyn-field method that it is deprecated and
will be removed in future.

>  For ``dpdk-testpmd`` application, it needs to stop and restart Tx port to take effect.
>  
> @@ -688,6 +690,15 @@ Usage::
>  
>      testpmd> set tx lldp on
>  
> +An alternative method for transmitting LLDP packets is to set the ``packet_type`` of
> +the mbuf to ``RTE_PTYPE_L2_ETHER_LLDP``. This, in conjunction with enabling the
> +``enable_ptype_lldp`` devarg will cause such packets to be transmitted::
> +
> +    -a 0000:xx:xx.x,enable_ptype_lldp=1
> +
> +When ``enable_ptype_lldp`` is not set (default), ptype-based LLDP detection is
> +disabled, but LLDP transmission via the dynamic mbuf field remains available.
> +

The previous method describes testpmd use. Do we need such a description
here too?

>  
>  Limitations or Knowing issues
>  -----------------------------
> diff --git a/doc/guides/rel_notes/release_26_07.rst b/doc/guides/rel_notes/release_26_07.rst
> index 060b26ff61..e0b27a554a 100644
> --- a/doc/guides/rel_notes/release_26_07.rst
> +++ b/doc/guides/rel_notes/release_26_07.rst
> @@ -56,6 +56,11 @@ New Features
>       =======================================================
>  
>  
> +* **Updated Intel iavf driver.**
> +
> +  * Added support for transmitting LLDP packets based on mbuf packet type.
> +
> +
>  Removed Items
>  -------------
>  
> diff --git a/drivers/net/intel/iavf/iavf.h b/drivers/net/intel/iavf/iavf.h
> index f8008d0fda..ef503a1b64 100644
> --- a/drivers/net/intel/iavf/iavf.h
> +++ b/drivers/net/intel/iavf/iavf.h
> @@ -323,6 +323,7 @@ struct iavf_devargs {
>  	int auto_reconfig;
>  	int no_poll_on_link_down;
>  	uint64_t mbuf_check;
> +	int enable_ptype_lldp;
>  };
>  
>  struct iavf_security_ctx;
> diff --git a/drivers/net/intel/iavf/iavf_ethdev.c b/drivers/net/intel/iavf/iavf_ethdev.c
> index 3126d9b644..77e8c6b54b 100644
> --- a/drivers/net/intel/iavf/iavf_ethdev.c
> +++ b/drivers/net/intel/iavf/iavf_ethdev.c
> @@ -44,9 +44,11 @@
>  #define IAVF_ENABLE_AUTO_RECONFIG_ARG "auto_reconfig"
>  #define IAVF_NO_POLL_ON_LINK_DOWN_ARG "no-poll-on-link-down"
>  #define IAVF_MBUF_CHECK_ARG       "mbuf_check"
> +#define IAVF_ENABLE_PTYPE_LLDP_ARG "enable_ptype_lldp"
>  uint64_t iavf_timestamp_dynflag;
>  int iavf_timestamp_dynfield_offset = -1;
>  int rte_pmd_iavf_tx_lldp_dynfield_offset = -1;
> +bool iavf_ptype_lldp_enabled;
>  
>  static const char * const iavf_valid_args[] = {
>  	IAVF_PROTO_XTR_ARG,
> @@ -56,6 +58,7 @@ static const char * const iavf_valid_args[] = {
>  	IAVF_ENABLE_AUTO_RECONFIG_ARG,
>  	IAVF_NO_POLL_ON_LINK_DOWN_ARG,
>  	IAVF_MBUF_CHECK_ARG,
> +	IAVF_ENABLE_PTYPE_LLDP_ARG,
>  	NULL
>  };
>  
> @@ -1016,6 +1019,11 @@ iavf_dev_start(struct rte_eth_dev *dev)
>  	/* Check Tx LLDP dynfield */
>  	rte_pmd_iavf_tx_lldp_dynfield_offset =
>  		rte_mbuf_dynfield_lookup(IAVF_TX_LLDP_DYNFIELD, NULL);
> +	if (rte_pmd_iavf_tx_lldp_dynfield_offset > 0)
> +		PMD_DRV_LOG(WARNING,
> +			"The LLDP Tx dynamic mbuf field will be removed in a future release.");

I think this message could do with being expanded and clarified, even if it
is longer. For example: "Using a dynamic mbuf field to identify LLDP
packets is deprecated. Set the 'enable_ptype_lldp' driver option and mbuf
LLDP ptypes instead"

> +	iavf_ptype_lldp_enabled = adapter->devargs.enable_ptype_lldp ||
> +					rte_pmd_iavf_tx_lldp_dynfield_offset > 0;
>  
>  	if (iavf_init_queues(dev) != 0) {
>  		PMD_DRV_LOG(ERR, "failed to do Queue init");
> @@ -2445,6 +2453,11 @@ static int iavf_parse_devargs(struct rte_eth_dev *dev)
>  	if (ret)
>  		goto bail;
>  
> +	ret = rte_kvargs_process(kvlist, IAVF_ENABLE_PTYPE_LLDP_ARG,
> +				 &parse_bool, &ad->devargs.enable_ptype_lldp);
> +	if (ret)
> +		goto bail;
> +
>  bail:
>  	rte_kvargs_free(kvlist);
>  	return ret;
> @@ -2795,6 +2808,8 @@ iavf_dev_init(struct rte_eth_dev *eth_dev)
>  		 */
>  		rte_pmd_iavf_tx_lldp_dynfield_offset =
>  			rte_mbuf_dynfield_lookup(IAVF_TX_LLDP_DYNFIELD, NULL);
> +		iavf_ptype_lldp_enabled = adapter->devargs.enable_ptype_lldp ||
> +						rte_pmd_iavf_tx_lldp_dynfield_offset > 0;
>  		iavf_set_tx_function(eth_dev);
>  		return 0;
>  	}
> diff --git a/drivers/net/intel/iavf/iavf_rxtx.c b/drivers/net/intel/iavf/iavf_rxtx.c
> index 4ff6c18dc4..bb62ab07de 100644
> --- a/drivers/net/intel/iavf/iavf_rxtx.c
> +++ b/drivers/net/intel/iavf/iavf_rxtx.c
> @@ -3886,7 +3886,7 @@ iavf_set_tx_function(struct rte_eth_dev *dev)
>  	if (iavf_tx_vec_dev_check(dev) != -1)
>  		req_features.simd_width = iavf_get_max_simd_bitwidth();
>  
> -	if (rte_pmd_iavf_tx_lldp_dynfield_offset > 0)
> +	if (iavf_ptype_lldp_enabled)
>  		req_features.ctx_desc = true;
>  
>  	for (i = 0; i < dev->data->nb_tx_queues; i++) {
> diff --git a/drivers/net/intel/iavf/iavf_rxtx.h b/drivers/net/intel/iavf/iavf_rxtx.h
> index 80b06518b0..0157c4c37e 100644
> --- a/drivers/net/intel/iavf/iavf_rxtx.h
> +++ b/drivers/net/intel/iavf/iavf_rxtx.h
> @@ -157,14 +157,15 @@
>  
>  #define IAVF_TX_LLDP_DYNFIELD "intel_pmd_dynfield_tx_lldp"
>  #define IAVF_CHECK_TX_LLDP(m) \
> -	((rte_pmd_iavf_tx_lldp_dynfield_offset > 0) && \
> -	(*RTE_MBUF_DYNFIELD((m), \
> -			rte_pmd_iavf_tx_lldp_dynfield_offset, \
> -			uint8_t *)))
> +	(iavf_ptype_lldp_enabled && \
> +	(((m)->packet_type & RTE_PTYPE_L2_MASK) == RTE_PTYPE_L2_ETHER_LLDP || \
> +	(rte_pmd_iavf_tx_lldp_dynfield_offset > 0 && \
> +	*RTE_MBUF_DYNFIELD((m), rte_pmd_iavf_tx_lldp_dynfield_offset, uint8_t *))))
>  
>  extern uint64_t iavf_timestamp_dynflag;
>  extern int iavf_timestamp_dynfield_offset;
>  extern int rte_pmd_iavf_tx_lldp_dynfield_offset;
> +extern bool iavf_ptype_lldp_enabled;
>  
>  typedef void (*iavf_rxd_to_pkt_fields_t)(struct ci_rx_queue *rxq,
>  				struct rte_mbuf *mb,
> -- 
> 2.43.0
>