Re: [dpdk-dev] [PATCH v2 1/6] net/af_xdp: introduce AF XDP PMD driver

["Mattias Rönnblom" <hofors@lysator.liu.se>]

On 2019-03-19 08:12, Xiaolong Ye wrote:
> Add a new PMD driver for AF_XDP which is a proposed faster version of
> AF_PACKET interface in Linux. More info about AF_XDP, please refer to [1]
> [2].
> 
> This is the vanilla version PMD which just uses a raw buffer registered as
> the umem.
> 
> [1] https://fosdem.org/2018/schedule/event/af_xdp/
> [2] https://lwn.net/Articles/745934/
> 
> Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
> ---
>   MAINTAINERS                                   |   6 +
>   config/common_base                            |   5 +
>   config/common_linux                           |   1 +
>   doc/guides/nics/af_xdp.rst                    |  45 +
>   doc/guides/nics/features/af_xdp.ini           |  11 +
>   doc/guides/nics/index.rst                     |   1 +
>   doc/guides/rel_notes/release_19_05.rst        |   7 +
>   drivers/net/Makefile                          |   1 +
>   drivers/net/af_xdp/Makefile                   |  33 +
>   drivers/net/af_xdp/meson.build                |  21 +
>   drivers/net/af_xdp/rte_eth_af_xdp.c           | 930 ++++++++++++++++++
>   drivers/net/af_xdp/rte_pmd_af_xdp_version.map |   3 +
>   drivers/net/meson.build                       |   1 +
>   mk/rte.app.mk                                 |   1 +
>   14 files changed, 1066 insertions(+)
>   create mode 100644 doc/guides/nics/af_xdp.rst
>   create mode 100644 doc/guides/nics/features/af_xdp.ini
>   create mode 100644 drivers/net/af_xdp/Makefile
>   create mode 100644 drivers/net/af_xdp/meson.build
>   create mode 100644 drivers/net/af_xdp/rte_eth_af_xdp.c
>   create mode 100644 drivers/net/af_xdp/rte_pmd_af_xdp_version.map
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 452b8eb82..1cc54b439 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -468,6 +468,12 @@ M: John W. Linville <linville@tuxdriver.com>
>   F: drivers/net/af_packet/
>   F: doc/guides/nics/features/afpacket.ini
>   
> +Linux AF_XDP
> +M: Xiaolong Ye <xiaolong.ye@intel.com>
> +M: Qi Zhang <qi.z.zhang@intel.com>
> +F: drivers/net/af_xdp/
> +F: doc/guides/nics/features/af_xdp.rst
> +
>   Amazon ENA
>   M: Marcin Wojtas <mw@semihalf.com>
>   M: Michal Krawczyk <mk@semihalf.com>
> diff --git a/config/common_base b/config/common_base
> index 0b09a9348..4044de205 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -416,6 +416,11 @@ CONFIG_RTE_LIBRTE_VMXNET3_DEBUG_TX_FREE=n
>   #
>   CONFIG_RTE_LIBRTE_PMD_AF_PACKET=n
>   
> +#
> +# Compile software PMD backed by AF_XDP sockets (Linux only)
> +#
> +CONFIG_RTE_LIBRTE_PMD_AF_XDP=n
> +
>   #
>   # Compile link bonding PMD library
>   #
> diff --git a/config/common_linux b/config/common_linux
> index 75334273d..0b1249da0 100644
> --- a/config/common_linux
> +++ b/config/common_linux
> @@ -19,6 +19,7 @@ CONFIG_RTE_LIBRTE_VHOST_POSTCOPY=n
>   CONFIG_RTE_LIBRTE_PMD_VHOST=y
>   CONFIG_RTE_LIBRTE_IFC_PMD=y
>   CONFIG_RTE_LIBRTE_PMD_AF_PACKET=y
> +CONFIG_RTE_LIBRTE_PMD_AF_XDP=y
>   CONFIG_RTE_LIBRTE_PMD_SOFTNIC=y
>   CONFIG_RTE_LIBRTE_PMD_TAP=y
>   CONFIG_RTE_LIBRTE_AVP_PMD=y
> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
> new file mode 100644
> index 000000000..dd5654dd1
> --- /dev/null
> +++ b/doc/guides/nics/af_xdp.rst
> @@ -0,0 +1,45 @@
> +..  SPDX-License-Identifier: BSD-3-Clause
> +    Copyright(c) 2018 Intel Corporation.
> +
> +AF_XDP Poll Mode Driver
> +==========================
> +
> +AF_XDP is an address family that is optimized for high performance
> +packet processing. AF_XDP sockets enable the possibility for XDP program to
> +redirect packets to a memory buffer in userspace.
> +
> +For the full details behind AF_XDP socket, you can refer to
> +`AF_XDP documentation in the Kernel
> +<https://www.kernel.org/doc/Documentation/networking/af_xdp.rst>`_.
> +
> +This Linux-specific PMD driver creates the AF_XDP socket and binds it to a
> +specific netdev queue, it allows a DPDK application to send and receive raw
> +packets through the socket which would bypass the kernel network stack.
> +Current implementation only supports single queue, multi-queues feature will
> +be added later.
> +
> +Options
> +-------
> +
> +The following options can be provided to set up an af_xdp port in DPDK.
> +
> +*   ``iface`` - name of the Kernel interface to attach to (required);
> +*   ``queue`` - netdev queue id (optional, default 0);
> +
> +Prerequisites
> +-------------
> +
> +This is a Linux-specific PMD, thus the following prerequisites apply:
> +
> +*  A Linux Kernel (version > 4.18) with XDP sockets configuration enabled;
> +*  libbpf (within kernel version > 5.1) with latest af_xdp support installed
> +*  A Kernel bound interface to attach to.
> +
> +Set up an af_xdp interface
> +-----------------------------
> +
> +The following example will set up an af_xdp interface in DPDK:
> +
> +.. code-block:: console
> +
> +    --vdev eth_af_xdp,iface=ens786f1,queue=0
> diff --git a/doc/guides/nics/features/af_xdp.ini b/doc/guides/nics/features/af_xdp.ini
> new file mode 100644
> index 000000000..7b8fcce00
> --- /dev/null
> +++ b/doc/guides/nics/features/af_xdp.ini
> @@ -0,0 +1,11 @@
> +;
> +; Supported features of the 'af_xdp' network poll mode driver.
> +;
> +; Refer to default.ini for the full list of available PMD features.
> +;
> +[Features]
> +Link status          = Y
> +MTU update           = Y
> +Promiscuous mode     = Y
> +Stats per queue      = Y
> +x86-64               = Y
> \ No newline at end of file
> diff --git a/doc/guides/nics/index.rst b/doc/guides/nics/index.rst
> index 5c80e3baa..a4b80a3d0 100644
> --- a/doc/guides/nics/index.rst
> +++ b/doc/guides/nics/index.rst
> @@ -12,6 +12,7 @@ Network Interface Controller Drivers
>       features
>       build_and_test
>       af_packet
> +    af_xdp
>       ark
>       atlantic
>       avp
> diff --git a/doc/guides/rel_notes/release_19_05.rst b/doc/guides/rel_notes/release_19_05.rst
> index 61a2c7383..062facf89 100644
> --- a/doc/guides/rel_notes/release_19_05.rst
> +++ b/doc/guides/rel_notes/release_19_05.rst
> @@ -65,6 +65,13 @@ New Features
>       process.
>     * Added support for Rx packet types list in a secondary process.
>   
> +* **Added the AF_XDP PMD.**
> +
> +  Added a Linux-specific PMD driver for AF_XDP, it can create the AF_XDP socket
> +  and bind it to a specific netdev queue, it allows a DPDK application to send
> +  and receive raw packets through the socket which would bypass the kernel
> +  network stack to achieve high performance packet processing.
> +
>   * **Updated Mellanox drivers.**
>   
>      New features and improvements were done in mlx4 and mlx5 PMDs:
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 502869a87..5d401b8c5 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -9,6 +9,7 @@ ifeq ($(CONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD),d)
>   endif
>   
>   DIRS-$(CONFIG_RTE_LIBRTE_PMD_AF_PACKET) += af_packet
> +DIRS-$(CONFIG_RTE_LIBRTE_PMD_AF_XDP) += af_xdp
>   DIRS-$(CONFIG_RTE_LIBRTE_ARK_PMD) += ark
>   DIRS-$(CONFIG_RTE_LIBRTE_ATLANTIC_PMD) += atlantic
>   DIRS-$(CONFIG_RTE_LIBRTE_AVP_PMD) += avp
> diff --git a/drivers/net/af_xdp/Makefile b/drivers/net/af_xdp/Makefile
> new file mode 100644
> index 000000000..6cf0ed7db
> --- /dev/null
> +++ b/drivers/net/af_xdp/Makefile
> @@ -0,0 +1,33 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2018 Intel Corporation
> +
> +include $(RTE_SDK)/mk/rte.vars.mk
> +
> +#
> +# library name
> +#
> +LIB = librte_pmd_af_xdp.a
> +
> +EXPORT_MAP := rte_pmd_af_xdp_version.map
> +
> +LIBABIVER := 1
> +
> +CFLAGS += -O3
> +
> +# require kernel version >= v5.1-rc1
> +LINUX_VERSION := $(shell uname -r)
> +CFLAGS += -I/lib/modules/$(LINUX_VERSION)/build/tools/include
> +CFLAGS += -I/lib/modules/$(LINUX_VERSION)/build/tools/lib/bpf
> +
> +CFLAGS += $(WERROR_FLAGS)
> +LDLIBS += -lrte_eal -lrte_mbuf -lrte_mempool -lrte_ring
> +LDLIBS += -lrte_ethdev -lrte_net -lrte_kvargs
> +LDLIBS += -lrte_bus_vdev
> +LDLIBS += -lbpf
> +
> +#
> +# all source are stored in SRCS-y
> +#
> +SRCS-$(CONFIG_RTE_LIBRTE_PMD_AF_XDP) += rte_eth_af_xdp.c
> +
> +include $(RTE_SDK)/mk/rte.lib.mk
> diff --git a/drivers/net/af_xdp/meson.build b/drivers/net/af_xdp/meson.build
> new file mode 100644
> index 000000000..635e67483
> --- /dev/null
> +++ b/drivers/net/af_xdp/meson.build
> @@ -0,0 +1,21 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2018 Intel Corporation
> +
> +if host_machine.system() != 'linux'
> +	build = false
> +endif
> +
> +bpf_dep = dependency('libbpf', required: false)
> +if bpf_dep.found()
> +	build = true
> +else
> +	bpf_dep = cc.find_library('libbpf', required: false)
> +	if bpf_dep.found() and cc.has_header('xsk.h', dependencies: bpf_dep)
> +		build = true
> +		pkgconfig_extra_libs += '-lbpf'
> +	else
> +		build = false
> +	endif
> +endif
> +sources = files('rte_eth_af_xdp.c')
> +ext_deps += bpf_dep
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> new file mode 100644
> index 000000000..96dedc0c4
> --- /dev/null
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -0,0 +1,930 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Intel Corporation.
> + */
> +
> +#include <rte_mbuf.h>
> +#include <rte_ethdev_driver.h>
> +#include <rte_ethdev_vdev.h>
> +#include <rte_malloc.h>
> +#include <rte_kvargs.h>
> +#include <rte_bus_vdev.h>
> +#include <rte_string_fns.h>
> +
> +#include <linux/if_ether.h>
> +#include <linux/if_xdp.h>
> +#include <linux/if_link.h>
> +#include <asm/barrier.h>

Is this include used?

> +#include <arpa/inet.h>
> +#include <net/if.h>
> +#include <sys/types.h>
> +#include <sys/socket.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <unistd.h>
> +#include <poll.h>
> +#include <bpf/bpf.h>
> +#include <xsk.h>
> +
> +#define RTE_LOGTYPE_AF_XDP RTE_LOGTYPE_USER1
> +#ifndef SOL_XDP
> +#define SOL_XDP 283
> +#endif
> +
> +#ifndef AF_XDP
> +#define AF_XDP 44
> +#endif
> +
> +#ifndef PF_XDP
> +#define PF_XDP AF_XDP
> +#endif
> +
> +#define ETH_AF_XDP_IFACE_ARG			"iface"
> +#define ETH_AF_XDP_QUEUE_IDX_ARG		"queue"
> +
> +#define ETH_AF_XDP_FRAME_SIZE		XSK_UMEM__DEFAULT_FRAME_SIZE
> +#define ETH_AF_XDP_NUM_BUFFERS		4096
> +#define ETH_AF_XDP_DATA_HEADROOM	0
> +#define ETH_AF_XDP_DFLT_NUM_DESCS	XSK_RING_CONS__DEFAULT_NUM_DESCS
> +#define ETH_AF_XDP_DFLT_QUEUE_IDX	0
> +
> +#define ETH_AF_XDP_RX_BATCH_SIZE	32
> +#define ETH_AF_XDP_TX_BATCH_SIZE	32
> +
> +#define ETH_AF_XDP_MAX_QUEUE_PAIRS     16
> +
> +struct xsk_umem_info {
> +	struct xsk_ring_prod fq;
> +	struct xsk_ring_cons cq;
> +	struct xsk_umem *umem;
> +	struct rte_ring *buf_ring;
> +	void *buffer;
> +};
> +
> +struct pkt_rx_queue {
> +	struct xsk_ring_cons rx;
> +	struct xsk_umem_info *umem;
> +	struct xsk_socket *xsk;
> +	struct rte_mempool *mb_pool;
> +
> +	uint64_t rx_pkts;
> +	uint64_t rx_bytes;
> +	uint64_t rx_dropped;
> +
> +	struct pkt_tx_queue *pair;
> +	uint16_t queue_idx;
> +};
> +
> +struct pkt_tx_queue {
> +	struct xsk_ring_prod tx;
> +
> +	uint64_t tx_pkts;
> +	uint64_t err_pkts;
> +	uint64_t tx_bytes;
> +
> +	struct pkt_rx_queue *pair;
> +	uint16_t queue_idx;
> +};
> +
> +struct pmd_internals {
> +	int if_index;
> +	char if_name[IFNAMSIZ];
> +	uint16_t queue_idx;
> +	struct ether_addr eth_addr;
> +	struct xsk_umem_info *umem;
> +	struct rte_mempool *mb_pool_share;
> +
> +	struct pkt_rx_queue rx_queues[ETH_AF_XDP_MAX_QUEUE_PAIRS];
> +	struct pkt_tx_queue tx_queues[ETH_AF_XDP_MAX_QUEUE_PAIRS];
> +};
> +
> +static const char * const valid_arguments[] = {
> +	ETH_AF_XDP_IFACE_ARG,
> +	ETH_AF_XDP_QUEUE_IDX_ARG,
> +	NULL
> +};
> +
> +static struct rte_eth_link pmd_link = {
> +	.link_speed = ETH_SPEED_NUM_10G,
> +	.link_duplex = ETH_LINK_FULL_DUPLEX,
> +	.link_status = ETH_LINK_DOWN,
> +	.link_autoneg = ETH_LINK_AUTONEG
> +};
> +
> +static inline int
> +reserve_fill_queue(struct xsk_umem_info *umem, int reserve_size)
> +{
> +	struct xsk_ring_prod *fq = &umem->fq;
> +	uint32_t idx;
> +	void *addr = NULL;
> +	int i, ret = 0;

No need to initialize 'ret'. Is there a point to set 'addr'?

> +
> +	ret = xsk_ring_prod__reserve(fq, reserve_size, &idx);
> +	if (!ret) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to reserve enough fq descs.\n");
> +		return ret;
> +	}
> +
> +	for (i = 0; i < reserve_size; i++) {
> +		rte_ring_dequeue(umem->buf_ring, &addr);
> +		*xsk_ring_prod__fill_addr(fq, idx++) = (uint64_t)addr;

Consider introducing a tmp variable to make this more readable.

> +	}
> +
> +	xsk_ring_prod__submit(fq, reserve_size);
> +
> +	return 0;
> +}
> +
> +static uint16_t
> +eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
> +{
> +	struct pkt_rx_queue *rxq = queue;
> +	struct xsk_ring_cons *rx = &rxq->rx;
> +	struct xsk_umem_info *umem = rxq->umem;
> +	struct xsk_ring_prod *fq = &umem->fq;
> +	uint32_t idx_rx;
> +	uint32_t free_thresh = fq->size >> 1;
> +	struct rte_mbuf *mbuf;
> +	unsigned long dropped = 0;
> +	unsigned long rx_bytes = 0;
> +	uint16_t count = 0;
> +	int rcvd, i;
> +
> +	nb_pkts = nb_pkts < ETH_AF_XDP_RX_BATCH_SIZE ?
> +		nb_pkts : ETH_AF_XDP_RX_BATCH_SIZE;
> +
> +	rcvd = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx); > +	if (!rcvd)

Since peek returns the number of entries, not a boolean, do:
rcvd == 0

> +		return 0;
> +
> +	if (xsk_prod_nb_free(fq, free_thresh) >= free_thresh)
> +		(void)reserve_fill_queue(umem, ETH_AF_XDP_RX_BATCH_SIZE);
> +
> +	for (i = 0; i < rcvd; i++) {
> +		uint64_t addr = xsk_ring_cons__rx_desc(rx, idx_rx)->addr;
> +		uint32_t len = xsk_ring_cons__rx_desc(rx, idx_rx++)->len;

Use a tmp variable, instead of two calls.

> +		char *pkt = xsk_umem__get_data(rxq->umem->buffer, addr);
> +

Don't mix declaration and code. Why is this a char pointer? As opppose 
to void.

> +		mbuf = rte_pktmbuf_alloc(rxq->mb_pool);
> +		if (mbuf) {

1.8.1

> +			memcpy(rte_pktmbuf_mtod(mbuf, void*), pkt, len);

rte_memcpy()

> +			rte_pktmbuf_pkt_len(mbuf) =
> +				rte_pktmbuf_data_len(mbuf) = len;

Consider splitting this into two statements.

> +			rx_bytes += len;
> +			bufs[count++] = mbuf;
> +		} else {
> +			dropped++;
> +		}
> +		rte_ring_enqueue(umem->buf_ring, (void *)addr);
> +	}
> +
> +	xsk_ring_cons__release(rx, rcvd);
> +
> +	/* statistics */
> +	rxq->rx_pkts += (rcvd - dropped);
> +	rxq->rx_bytes += rx_bytes;
> +	rxq->rx_dropped += dropped;
> +
> +	return count;
> +}
> +
> +static void pull_umem_cq(struct xsk_umem_info *umem, int size)
> +{
> +	struct xsk_ring_cons *cq = &umem->cq;
> +	int i, n;
> +	uint32_t idx_cq;
> +	uint64_t addr;
> +
> +	n = xsk_ring_cons__peek(cq, size, &idx_cq);

Use size_t for n.

> +	if (n > 0) {
> +		for (i = 0; i < n; i++) {

Consider declaring 'addr' in this scope.

> +			addr = *xsk_ring_cons__comp_addr(cq,
> +							 idx_cq++); > +			rte_ring_enqueue(umem->buf_ring, (void *)addr);
> +		}
> +
> +		xsk_ring_cons__release(cq, n);
> +	}
> +}
> +
> +static void kick_tx(struct pkt_tx_queue *txq)
> +{
> +	struct xsk_umem_info *umem = txq->pair->umem;
> +	int ret;
> +
> +	while (1) {

for (;;)

> +		ret = sendto(xsk_socket__fd(txq->pair->xsk), NULL, 0,
> +			     MSG_DONTWAIT, NULL, 0);
> +
> +		/* everything is ok */
> +		if (ret >= 0)

Use likely()?

> +			break;
> +
> +		/* some thing unexpected */
> +		if (errno != EBUSY && errno != EAGAIN)
> +			break;
> +
> +		/* pull from complete qeueu to leave more space */
> +		if (errno == EAGAIN)
> +			pull_umem_cq(umem, ETH_AF_XDP_TX_BATCH_SIZE);
> +	}
> +	pull_umem_cq(umem, ETH_AF_XDP_TX_BATCH_SIZE);
> +}
> +
> +static uint16_t
> +eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
> +{
> +	struct pkt_tx_queue *txq = queue;
> +	struct xsk_umem_info *umem = txq->pair->umem;
> +	struct rte_mbuf *mbuf;
> +	void *addrs[ETH_AF_XDP_TX_BATCH_SIZE];
> +	unsigned long tx_bytes = 0;
> +	int i, valid = 0;
> +	uint32_t idx_tx;
> +
> +	nb_pkts = nb_pkts < ETH_AF_XDP_TX_BATCH_SIZE ?
> +		nb_pkts : ETH_AF_XDP_TX_BATCH_SIZE;

Use RTE_MIN().

> +
> +	pull_umem_cq(umem, nb_pkts);
> +
> +	nb_pkts = rte_ring_dequeue_bulk(umem->buf_ring, addrs,
> +					nb_pkts, NULL);
> +	if (!nb_pkts)

nb_pkts == 0

> +		return 0;
> +
> +	if (xsk_ring_prod__reserve(&txq->tx, nb_pkts, &idx_tx) != nb_pkts) {
> +		kick_tx(txq);
> +		return 0;
> +	}
> +
> +	for (i = 0; i < nb_pkts; i++) {
> +		struct xdp_desc *desc;
> +		char *pkt;

Use void pointer?

> +		unsigned int buf_len = ETH_AF_XDP_FRAME_SIZE
> +					- ETH_AF_XDP_DATA_HEADROOM;

Use uint32_t, as you seem to do elsewhere.

> +		desc = xsk_ring_prod__tx_desc(&txq->tx, idx_tx + i);
> +		mbuf = bufs[i];
> +		if (mbuf->pkt_len <= buf_len) {
> +			desc->addr = (uint64_t)addrs[valid];
> +			desc->len = mbuf->pkt_len;
> +			pkt = xsk_umem__get_data(umem->buffer,
> +						 desc->addr);
> +			memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
> +			       desc->len);

rte_memcpy()

> +			valid++;
> +			tx_bytes += mbuf->pkt_len;
> +		}
> +		rte_pktmbuf_free(mbuf);
> +	}
> +
> +	xsk_ring_prod__submit(&txq->tx, nb_pkts);
> +
> +	kick_tx(txq);
> +
> +	if (valid < nb_pkts)
> +		rte_ring_enqueue_bulk(umem->buf_ring, &addrs[valid],
> +				 nb_pkts - valid, NULL);
> +
> +	txq->err_pkts += nb_pkts - valid;
> +	txq->tx_pkts += valid;
> +	txq->tx_bytes += tx_bytes;
> +
> +	return nb_pkts;
> +}
> +
> +static int
> +eth_dev_start(struct rte_eth_dev *dev)
> +{
> +	dev->data->dev_link.link_status = ETH_LINK_UP;
> +
> +	return 0;
> +}
> +
> +/* This function gets called when the current port gets stopped. */
> +static void
> +eth_dev_stop(struct rte_eth_dev *dev)
> +{
> +	dev->data->dev_link.link_status = ETH_LINK_DOWN;
> +}
> +
> +static int
> +eth_dev_configure(struct rte_eth_dev *dev __rte_unused)
> +{
> +	/* rx/tx must be paired */
> +	if (dev->data->nb_rx_queues != dev->data->nb_tx_queues)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void
> +eth_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +
> +	dev_info->if_index = internals->if_index;
> +	dev_info->max_mac_addrs = 1;
> +	dev_info->max_rx_pktlen = (uint32_t)ETH_FRAME_LEN;
> +	dev_info->max_rx_queues = 1;
> +	dev_info->max_tx_queues = 1;
> +	dev_info->min_rx_bufsize = 0;
> +
> +	dev_info->default_rxportconf.nb_queues = 1;
> +	dev_info->default_txportconf.nb_queues = 1;
> +	dev_info->default_rxportconf.ring_size = ETH_AF_XDP_DFLT_NUM_DESCS;
> +	dev_info->default_txportconf.ring_size = ETH_AF_XDP_DFLT_NUM_DESCS;
> +}
> +
> +static int
> +eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	struct xdp_statistics xdp_stats;
> +	struct pkt_rx_queue *rxq;
> +	socklen_t optlen;
> +	int i;
> +
> +	optlen = sizeof(struct xdp_statistics);
> +	for (i = 0; i < dev->data->nb_rx_queues; i++) {
> +		rxq = &internals->rx_queues[i];
> +		stats->q_ipackets[i] = internals->rx_queues[i].rx_pkts;
> +		stats->q_ibytes[i] = internals->rx_queues[i].rx_bytes;
> +
> +		stats->q_opackets[i] = internals->tx_queues[i].tx_pkts;
> +		stats->q_obytes[i] = internals->tx_queues[i].tx_bytes;
> +
> +		stats->ipackets += stats->q_ipackets[i];
> +		stats->ibytes += stats->q_ibytes[i];
> +		stats->imissed += internals->rx_queues[i].rx_dropped;
> +		getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP, XDP_STATISTICS,
> +				&xdp_stats, &optlen);
> +		stats->imissed += xdp_stats.rx_dropped;
> +
> +		stats->opackets += stats->q_opackets[i];
> +		stats->oerrors += stats->q_errors[i];
> +		stats->oerrors += internals->tx_queues[i].err_pkts;
> +		stats->obytes += stats->q_obytes[i];
> +	}
> +
> +	return 0;
> +}
> +
> +static void
> +eth_stats_reset(struct rte_eth_dev *dev)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	int i;
> +
> +	for (i = 0; i < ETH_AF_XDP_MAX_QUEUE_PAIRS; i++) {
> +		internals->rx_queues[i].rx_pkts = 0;
> +		internals->rx_queues[i].rx_bytes = 0;
> +		internals->rx_queues[i].rx_dropped = 0;
> +
> +		internals->tx_queues[i].tx_pkts = 0;
> +		internals->tx_queues[i].err_pkts = 0;
> +		internals->tx_queues[i].tx_bytes = 0;
> +	}
> +}
> +
> +static void remove_xdp_program(struct pmd_internals *internals)
> +{
> +	uint32_t curr_prog_id = 0;
> +
> +	if (bpf_get_link_xdp_id(internals->if_index, &curr_prog_id,
> +				XDP_FLAGS_UPDATE_IF_NOEXIST)) {
> +		RTE_LOG(ERR, AF_XDP, "bpf_get_link_xdp_id failed\n");
> +		return;
> +	}
> +	bpf_set_link_xdp_fd(internals->if_index, -1,
> +			XDP_FLAGS_UPDATE_IF_NOEXIST);
> +}
> +
> +static void
> +eth_dev_close(struct rte_eth_dev *dev)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	struct pkt_rx_queue *rxq;
> +	int i;
> +
> +	RTE_LOG(INFO, AF_XDP, "Closing AF_XDP ethdev on numa socket %u\n",
> +		rte_socket_id());
> +
> +	for (i = 0; i < ETH_AF_XDP_MAX_QUEUE_PAIRS; i++) {
> +		rxq = &internals->rx_queues[i];
> +		if (!rxq->umem)
> +			break;
> +		xsk_socket__delete(rxq->xsk);
> +	}
> +
> +	(void)xsk_umem__delete(internals->umem->umem);
> +	remove_xdp_program(internals);
> +}
> +
> +static void
> +eth_queue_release(void *q __rte_unused)
> +{
> +}
> +
> +static int
> +eth_link_update(struct rte_eth_dev *dev __rte_unused,
> +		int wait_to_complete __rte_unused)
> +{
> +	return 0;
> +}
> +
> +static void xdp_umem_destroy(struct xsk_umem_info *umem)
> +{
> +	free(umem->buffer);
> +	umem->buffer = NULL;
> +
> +	rte_ring_free(umem->buf_ring);
> +	umem->buf_ring = NULL;
> +
> +	free(umem);
> +	umem = NULL;
> +}
> +
> +static struct xsk_umem_info *xdp_umem_configure(void)
> +{
> +	struct xsk_umem_info *umem;
> +	struct xsk_umem_config usr_config = {
> +		.fill_size = ETH_AF_XDP_DFLT_NUM_DESCS,
> +		.comp_size = ETH_AF_XDP_DFLT_NUM_DESCS,
> +		.frame_size = ETH_AF_XDP_FRAME_SIZE,
> +		.frame_headroom = ETH_AF_XDP_DATA_HEADROOM };
> +	void *bufs = NULL;
> +	char ring_name[0x100];
> +	int ret;
> +	uint64_t i;
> +
> +	umem = calloc(1, sizeof(*umem));
> +	if (!umem) {

1.8.1

> +		RTE_LOG(ERR, AF_XDP, "Failed to allocate umem info");
> +		return NULL;
> +	}
> +
> +	snprintf(ring_name, 0x100, "af_xdp_ring");

Again the magical 0x100.

> +	umem->buf_ring = rte_ring_create(ring_name,
> +					 ETH_AF_XDP_NUM_BUFFERS,
> +					 SOCKET_ID_ANY,
> +					 0x0);
> +	if (!umem->buf_ring) {

1.8.1

> +		RTE_LOG(ERR, AF_XDP,
> +			"Failed to create rte_ring\n");
> +		goto err;
> +	}
> +
> +	for (i = 0; i < ETH_AF_XDP_NUM_BUFFERS; i++)
> +		rte_ring_enqueue(umem->buf_ring,
> +				 (void *)(i * ETH_AF_XDP_FRAME_SIZE +
> +					  ETH_AF_XDP_DATA_HEADROOM));
> +
> +	if (posix_memalign(&bufs, getpagesize(),
> +			   ETH_AF_XDP_NUM_BUFFERS * ETH_AF_XDP_FRAME_SIZE)) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to allocate memory pool.\n");
> +		goto err;
> +	}
> +	ret = xsk_umem__create(&umem->umem, bufs,
> +			       ETH_AF_XDP_NUM_BUFFERS * ETH_AF_XDP_FRAME_SIZE,
> +			       &umem->fq, &umem->cq,
> +			       &usr_config);
> +
> +	if (ret) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to create umem");
> +		goto err;
> +	}
> +	umem->buffer = bufs;
> +
> +	return umem;
> +
> +err:
> +	xdp_umem_destroy(umem);
> +	return NULL;
> +}
> +
> +static int
> +xsk_configure(struct pmd_internals *internals, struct pkt_rx_queue *rxq,
> +	      int ring_size)
> +{
> +	struct xsk_socket_config cfg;
> +	struct pkt_tx_queue *txq = rxq->pair;
> +	int ret = 0;
> +	int reserve_size;
> +
> +	rxq->umem = xdp_umem_configure();
> +	if (!rxq->umem) {

1.8.1

> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	cfg.rx_size = ring_size;
> +	cfg.tx_size = ring_size;
> +	cfg.libbpf_flags = 0;
> +	cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
> +	cfg.bind_flags = 0;
> +	ret = xsk_socket__create(&rxq->xsk, internals->if_name,
> +			internals->queue_idx, rxq->umem->umem, &rxq->rx,
> +			&txq->tx, &cfg);
> +	if (ret) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to create xsk socket.\n");
> +		goto err;
> +	}
> +
> +	reserve_size = ETH_AF_XDP_DFLT_NUM_DESCS / 2;
> +	ret = reserve_fill_queue(rxq->umem, reserve_size);
> +	if (ret) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to reserve fill queue.\n");
> +		goto err;
> +	}
> +
> +	return 0;
> +
> +err:
> +	xdp_umem_destroy(rxq->umem);
> +
> +	return ret;
> +}
> +
> +static void
> +queue_reset(struct pmd_internals *internals, uint16_t queue_idx)
> +{
> +	struct pkt_rx_queue *rxq = &internals->rx_queues[queue_idx];
> +	struct pkt_tx_queue *txq = rxq->pair;
> +	int xsk_fd = xsk_socket__fd(rxq->xsk);
> +
> +	if (xsk_fd) {
> +		close(xsk_fd);
> +		if (internals->umem) {

1.8.1

> +			xdp_umem_destroy(internals->umem);
> +			internals->umem = NULL;
> +		}
> +	}
> +	memset(rxq, 0, sizeof(*rxq));
> +	memset(txq, 0, sizeof(*txq));
> +	rxq->pair = txq;
> +	txq->pair = rxq;
> +	rxq->queue_idx = queue_idx;
> +	txq->queue_idx = queue_idx;
> +}
> +
> +static int
> +eth_rx_queue_setup(struct rte_eth_dev *dev,
> +		   uint16_t rx_queue_id,
> +		   uint16_t nb_rx_desc,
> +		   unsigned int socket_id __rte_unused,
> +		   const struct rte_eth_rxconf *rx_conf __rte_unused,
> +		   struct rte_mempool *mb_pool)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	unsigned int buf_size, data_size;

uint32_t

> +	struct pkt_rx_queue *rxq;
> +	int ret = 0;

No need to set 'ret'. Alternatively, restructure so you always return 'ret'.

> +
> +	rxq = &internals->rx_queues[rx_queue_id];
> +	queue_reset(internals, rx_queue_id);
> +
> +	/* Now get the space available for data in the mbuf */
> +	buf_size = rte_pktmbuf_data_room_size(mb_pool) -
> +		RTE_PKTMBUF_HEADROOM;
> +	data_size = ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM;
> +
> +	if (data_size > buf_size) {
> +		RTE_LOG(ERR, AF_XDP,
> +			"%s: %d bytes will not fit in mbuf (%d bytes)\n",
> +			dev->device->name, data_size, buf_size);
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	rxq->mb_pool = mb_pool;
> +
> +	if (xsk_configure(internals, rxq, nb_rx_desc)) {
> +		RTE_LOG(ERR, AF_XDP,
> +			"Failed to configure xdp socket\n");
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +
> +	internals->umem = rxq->umem;
> +
> +	dev->data->rx_queues[rx_queue_id] = rxq;
> +	return 0;
> +
> +err:
> +	queue_reset(internals, rx_queue_id);
> +	return ret;
> +}
> +
> +static int
> +eth_tx_queue_setup(struct rte_eth_dev *dev,
> +		   uint16_t tx_queue_id,
> +		   uint16_t nb_tx_desc __rte_unused,
> +		   unsigned int socket_id __rte_unused,
> +		   const struct rte_eth_txconf *tx_conf __rte_unused)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	struct pkt_tx_queue *txq;
> +
> +	txq = &internals->tx_queues[tx_queue_id];
> +
> +	dev->data->tx_queues[tx_queue_id] = txq;
> +	return 0;
> +}
> +
> +static int
> +eth_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	struct ifreq ifr = { .ifr_mtu = mtu };
> +	int ret;
> +	int s;
> +
> +	s = socket(PF_INET, SOCK_DGRAM, 0);
> +	if (s < 0)
> +		return -EINVAL;
> +
> +	strlcpy(ifr.ifr_name, internals->if_name, IFNAMSIZ);
> +	ret = ioctl(s, SIOCSIFMTU, &ifr);
> +	close(s);
> +
> +	if (ret < 0)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void
> +eth_dev_change_flags(char *if_name, uint32_t flags, uint32_t mask)
> +{
> +	struct ifreq ifr;
> +	int s;
> +
> +	s = socket(PF_INET, SOCK_DGRAM, 0);
> +	if (s < 0)
> +		return;
> +
> +	strlcpy(ifr.ifr_name, if_name, IFNAMSIZ);
> +	if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0)
> +		goto out;
> +	ifr.ifr_flags &= mask;
> +	ifr.ifr_flags |= flags;
> +	if (ioctl(s, SIOCSIFFLAGS, &ifr) < 0)
> +		goto out;
> +out:
> +	close(s);
> +}
> +
> +static void
> +eth_dev_promiscuous_enable(struct rte_eth_dev *dev)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +
> +	eth_dev_change_flags(internals->if_name, IFF_PROMISC, ~0);
> +}
> +
> +static void
> +eth_dev_promiscuous_disable(struct rte_eth_dev *dev)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +
> +	eth_dev_change_flags(internals->if_name, 0, ~IFF_PROMISC);
> +}
> +
> +static const struct eth_dev_ops ops = {
> +	.dev_start = eth_dev_start,
> +	.dev_stop = eth_dev_stop,
> +	.dev_close = eth_dev_close,
> +	.dev_configure = eth_dev_configure,
> +	.dev_infos_get = eth_dev_info,
> +	.mtu_set = eth_dev_mtu_set,
> +	.promiscuous_enable = eth_dev_promiscuous_enable,
> +	.promiscuous_disable = eth_dev_promiscuous_disable,
> +	.rx_queue_setup = eth_rx_queue_setup,
> +	.tx_queue_setup = eth_tx_queue_setup,
> +	.rx_queue_release = eth_queue_release,
> +	.tx_queue_release = eth_queue_release,
> +	.link_update = eth_link_update,
> +	.stats_get = eth_stats_get,
> +	.stats_reset = eth_stats_reset,
> +};
> +
> +/** parse integer from integer argument */
> +static int
> +parse_integer_arg(const char *key __rte_unused,
> +		  const char *value, void *extra_args)
> +{
> +	int *i = (int *)extra_args;
> +
> +	*i = atoi(value);

Use strtol().

> +	if (*i < 0) {
> +		RTE_LOG(ERR, AF_XDP, "Argument has to be positive.\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +/** parse name argument */
> +static int
> +parse_name_arg(const char *key __rte_unused,
> +	       const char *value, void *extra_args)
> +{
> +	char *name = extra_args;
> +
> +	if (strlen(value) > IFNAMSIZ) {

The buffer is IFNAMSIZ bytes (which it should be), so it can't hold a 
string with strlen() == IFNAMSIZ.

> +		RTE_LOG(ERR, AF_XDP, "Invalid name %s, should be less than "
> +			"%u bytes.\n", value, IFNAMSIZ);
> +		return -EINVAL;
> +	}
> +
> +	strlcpy(name, value, IFNAMSIZ);
> +
> +	return 0;
> +}
> +
> +static int
> +parse_parameters(struct rte_kvargs *kvlist,
> +		 char *if_name,
> +		 int *queue_idx)
> +{
> +	int ret = 0;

Should not be initialized.

> +
> +	ret = rte_kvargs_process(kvlist, ETH_AF_XDP_IFACE_ARG,
> +				 &parse_name_arg, if_name);
> +	if (ret < 0)
> +		goto free_kvlist;
> +
> +	ret = rte_kvargs_process(kvlist, ETH_AF_XDP_QUEUE_IDX_ARG,
> +				 &parse_integer_arg, queue_idx);
> +	if (ret < 0)
> +		goto free_kvlist;

I fail to see the point of this goto, but maybe there's more code to 
follow in future patches.

> +
> +free_kvlist:
> +	rte_kvargs_free(kvlist);
> +	return ret;
> +}
> +
> +static int
> +get_iface_info(const char *if_name,
> +	       struct ether_addr *eth_addr,
> +	       int *if_index)
> +{
> +	struct ifreq ifr;
> +	int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
> +
> +	if (sock < 0)
> +		return -1;
> +
> +	strlcpy(ifr.ifr_name, if_name, IFNAMSIZ);
> +	if (ioctl(sock, SIOCGIFINDEX, &ifr))
> +		goto error;
> +
> +	if (ioctl(sock, SIOCGIFHWADDR, &ifr))
> +		goto error;
> +
> +	rte_memcpy(eth_addr, ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
> +
> +	close(sock);
> +	*if_index = if_nametoindex(if_name);
> +	return 0;
> +
> +error:
> +	close(sock);
> +	return -1;
> +}
> +
> +static int
> +init_internals(struct rte_vdev_device *dev,
> +	       const char *if_name,
> +	       int queue_idx,
> +	       struct rte_eth_dev **eth_dev)
> +{
> +	const char *name = rte_vdev_device_name(dev);
> +	const unsigned int numa_node = dev->device.numa_node;
> +	struct pmd_internals *internals = NULL;
> +	int ret;
> +	int i;
> +
> +	internals = rte_zmalloc_socket(name, sizeof(*internals), 0, numa_node);
> +	if (!internals)

1.8.1

> +		return -ENOMEM;
> +
> +	internals->queue_idx = queue_idx;
> +	strlcpy(internals->if_name, if_name, IFNAMSIZ);
> +
> +	for (i = 0; i < ETH_AF_XDP_MAX_QUEUE_PAIRS; i++) {
> +		internals->tx_queues[i].pair = &internals->rx_queues[i];
> +		internals->rx_queues[i].pair = &internals->tx_queues[i];
> +	}
> +
> +	ret = get_iface_info(if_name, &internals->eth_addr,
> +			     &internals->if_index);
> +	if (ret)
> +		goto err;
> +
> +	*eth_dev = rte_eth_vdev_allocate(dev, 0);
> +	if (!*eth_dev)

1.8.1

> +		goto err;
> +
> +	(*eth_dev)->data->dev_private = internals;
> +	(*eth_dev)->data->dev_link = pmd_link;
> +	(*eth_dev)->data->mac_addrs = &internals->eth_addr;
> +	(*eth_dev)->dev_ops = &ops;
> +	(*eth_dev)->rx_pkt_burst = eth_af_xdp_rx;
> +	(*eth_dev)->tx_pkt_burst = eth_af_xdp_tx;
> +
> +	return 0;
> +
> +err:
> +	rte_free(internals);
> +	return -1;
> +}
> +
> +static int
> +rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
> +{
> +	struct rte_kvargs *kvlist;
> +	char if_name[IFNAMSIZ];
> +	int xsk_queue_idx = ETH_AF_XDP_DFLT_QUEUE_IDX;
> +	struct rte_eth_dev *eth_dev = NULL;
> +	const char *name;
> +	int ret;
> +
> +	RTE_LOG(INFO, AF_XDP, "Initializing pmd_af_xdp for %s\n",
> +		rte_vdev_device_name(dev));
> +
> +	name = rte_vdev_device_name(dev);
> +	if (rte_eal_process_type() == RTE_PROC_SECONDARY &&
> +		strlen(rte_vdev_device_args(dev)) == 0) {
> +		eth_dev = rte_eth_dev_attach_secondary(name);
> +		if (!eth_dev) {
> +			RTE_LOG(ERR, AF_XDP, "Failed to probe %s\n", name);
> +			return -EINVAL;
> +		}
> +		eth_dev->dev_ops = &ops;
> +		rte_eth_dev_probing_finish(eth_dev);
> +		return 0;
> +	}
> +
> +	kvlist = rte_kvargs_parse(rte_vdev_device_args(dev), valid_arguments);
> +	if (!kvlist) {
> +		RTE_LOG(ERR, AF_XDP, "Invalid kvargs key\n");
> +		return -EINVAL;
> +	}
> +
> +	if (dev->device.numa_node == SOCKET_ID_ANY)
> +		dev->device.numa_node = rte_socket_id();
> +
> +	if (parse_parameters(kvlist, if_name, &xsk_queue_idx) < 0) {
> +		RTE_LOG(ERR, AF_XDP, "Invalid kvargs value\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = init_internals(dev, if_name, xsk_queue_idx, &eth_dev);
> +	if (ret) {
> +		RTE_LOG(ERR, AF_XDP, "Failed to init internals\n");
> +		return ret;
> +	}
> +
> +	rte_eth_dev_probing_finish(eth_dev);
> +
> +	return 0;
> +}
> +
> +static int
> +rte_pmd_af_xdp_remove(struct rte_vdev_device *dev)
> +{
> +	struct rte_eth_dev *eth_dev = NULL;
> +	struct pmd_internals *internals;
> +
> +	RTE_LOG(INFO, AF_XDP, "Removing AF_XDP ethdev on numa socket %u\n",
> +		rte_socket_id());
> +
> +	if (!dev)
> +		return -1;
> +
> +	/* find the ethdev entry */
> +	eth_dev = rte_eth_dev_allocated(rte_vdev_device_name(dev));
> +	if (!eth_dev)
> +		return -1;
> +
> +	internals = eth_dev->data->dev_private;
> +
> +	rte_ring_free(internals->umem->buf_ring);
> +	rte_free(internals->umem->buffer);
> +	rte_free(internals->umem);
> +
> +	rte_eth_dev_release_port(eth_dev);
> +
> +
> +	return 0;
> +}
> +
> +static struct rte_vdev_driver pmd_af_xdp_drv = {
> +	.probe = rte_pmd_af_xdp_probe,
> +	.remove = rte_pmd_af_xdp_remove,
> +};
> +
> +RTE_PMD_REGISTER_VDEV(eth_af_xdp, pmd_af_xdp_drv);
> +RTE_PMD_REGISTER_PARAM_STRING(eth_af_xdp,
> +			      "iface=<string> "
> +			      "queue=<int> ");
> diff --git a/drivers/net/af_xdp/rte_pmd_af_xdp_version.map b/drivers/net/af_xdp/rte_pmd_af_xdp_version.map
> new file mode 100644
> index 000000000..c6db030fe
> --- /dev/null
> +++ b/drivers/net/af_xdp/rte_pmd_af_xdp_version.map
> @@ -0,0 +1,3 @@
> +DPDK_19.05 {
> +	local: *;
> +};
> diff --git a/drivers/net/meson.build b/drivers/net/meson.build
> index 3ecc78cee..1105e72d8 100644
> --- a/drivers/net/meson.build
> +++ b/drivers/net/meson.build
> @@ -2,6 +2,7 @@
>   # Copyright(c) 2017 Intel Corporation
>   
>   drivers = ['af_packet',
> +	'af_xdp',
>   	'ark',
>   	'atlantic',
>   	'avp',
> diff --git a/mk/rte.app.mk b/mk/rte.app.mk
> index 262132fc6..be0af73cc 100644
> --- a/mk/rte.app.mk
> +++ b/mk/rte.app.mk
> @@ -143,6 +143,7 @@ _LDLIBS-$(CONFIG_RTE_LIBRTE_DPAA2_MEMPOOL)  += -lrte_mempool_dpaa2
>   endif
>   
>   _LDLIBS-$(CONFIG_RTE_LIBRTE_PMD_AF_PACKET)  += -lrte_pmd_af_packet
> +_LDLIBS-$(CONFIG_RTE_LIBRTE_PMD_AF_XDP)     += -lrte_pmd_af_xdp -lelf -lbpf
>   _LDLIBS-$(CONFIG_RTE_LIBRTE_ARK_PMD)        += -lrte_pmd_ark
>   _LDLIBS-$(CONFIG_RTE_LIBRTE_ATLANTIC_PMD)   += -lrte_pmd_atlantic
>   _LDLIBS-$(CONFIG_RTE_LIBRTE_AVP_PMD)        += -lrte_pmd_avp
>