[dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[rkudurumalla]

This feature is used to create a hole between HEADROOM
and actual data.Size of hole is specified in bytes as
module param to pmd

Signed-off-by: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>
---
 doc/guides/nics/thunderx.rst         | 26 ++++++++++++
 drivers/net/thunderx/base/nicvf_hw.c | 12 ++++++
 drivers/net/thunderx/base/nicvf_hw.h |  1 +
 drivers/net/thunderx/nicvf_ethdev.c  | 76 +++++++++++++++++++++++++++++++++++-
 drivers/net/thunderx/nicvf_ethdev.h  |  1 +
 drivers/net/thunderx/nicvf_struct.h  |  1 +
 6 files changed, 116 insertions(+), 1 deletion(-)

diff --git a/doc/guides/nics/thunderx.rst b/doc/guides/nics/thunderx.rst
index 2642374..3d68c61 100644
--- a/doc/guides/nics/thunderx.rst
+++ b/doc/guides/nics/thunderx.rst
@@ -30,6 +30,7 @@ Features of the ThunderX PMD are:
 - SR-IOV VF
 - NUMA support
 - Multi queue set support (up to 96 queues (12 queue sets)) per port
+- First skip support
 
 Supported ThunderX SoCs
 -----------------------
@@ -312,6 +313,26 @@ We will choose four secondary queue sets from the ending of the list (0002:01:01
 
 The nicvf thunderx driver will make use of attached secondary VFs automatically during the interface configuration stage.
 
+
+# Module params
+
+    This feature is used to create a hole between HEADROOM and actual data.
+    Size of hole is specified in bytes as module param to pmd.
+
+Configuration and Options
+-------------------------
+    Use ``-w pci_id,skip_data_bytes="number of bytes to skip"`` in the EAL options
+    Example:
+
+    .. code-block:: console
+
+    ./your_application -w pci_id=skip_data_bytes=bytes_to_skip
+
+    Ex: ./build/app/testpmd -w 0001:01:00.1,skip_data_bytes=8 -- --rxq=1 --txq=1 --nb-cores=1 --port-topology=chained -i -- -c 0x1
+    This will create a hole of 8 bytes between HEADROOM and actual data.
+
+    Use case: The hole created with first_skip can be used to insert vlan header without disturbing HEADROOM
+
 Limitations
 -----------
 
@@ -335,3 +356,8 @@ Maximum packet segments
 The ThunderX SoC family NICs support up to 12 segments per packet when working
 in scatter/gather mode. So, setting MTU will result with ``EINVAL`` when the
 frame size does not fit in the maximum number of segments.
+
+First_skip
+~~~~~~~~~~
+
+Maximum limit on first_skip is 128 bytes and number of bytes should be multiple of 8
diff --git a/drivers/net/thunderx/base/nicvf_hw.c b/drivers/net/thunderx/base/nicvf_hw.c
index ea8092c..b07a293 100644
--- a/drivers/net/thunderx/base/nicvf_hw.c
+++ b/drivers/net/thunderx/base/nicvf_hw.c
@@ -703,6 +703,18 @@ nicvf_vlan_hw_strip(struct nicvf *nic, bool enable)
 }
 
 void
+nicvf_first_skip_config(struct nicvf *nic, uint8_t num_dwords)
+{
+	uint64_t val;
+
+	val = nicvf_reg_read(nic, NIC_VNIC_RQ_GEN_CFG);
+	val &= ~(0xfULL);
+	val |= (num_dwords & 0xf);
+
+	nicvf_reg_write(nic, NIC_VNIC_RQ_GEN_CFG, val);
+}
+
+void
 nicvf_apad_config(struct nicvf *nic, bool enable)
 {
 	uint64_t val;
diff --git a/drivers/net/thunderx/base/nicvf_hw.h b/drivers/net/thunderx/base/nicvf_hw.h
index 284d0bd..fd13ea8 100644
--- a/drivers/net/thunderx/base/nicvf_hw.h
+++ b/drivers/net/thunderx/base/nicvf_hw.h
@@ -193,6 +193,7 @@ uint32_t nicvf_qsize_sq_roundup(uint32_t val);
 void nicvf_vlan_hw_strip(struct nicvf *nic, bool enable);
 
 void nicvf_apad_config(struct nicvf *nic, bool enable);
+void nicvf_first_skip_config(struct nicvf *nic, uint8_t dwords);
 
 int nicvf_rss_config(struct nicvf *nic, uint32_t  qcnt, uint64_t cfg);
 int nicvf_rss_term(struct nicvf *nic);
diff --git a/drivers/net/thunderx/nicvf_ethdev.c b/drivers/net/thunderx/nicvf_ethdev.c
index 99fcd51..466cb86 100644
--- a/drivers/net/thunderx/nicvf_ethdev.c
+++ b/drivers/net/thunderx/nicvf_ethdev.c
@@ -34,6 +34,8 @@
 #include <rte_pci.h>
 #include <rte_bus_pci.h>
 #include <rte_tailq.h>
+#include <rte_devargs.h>
+#include <rte_kvargs.h>
 
 #include "base/nicvf_plat.h"
 
@@ -1230,6 +1232,7 @@ nicvf_rxq_mbuf_setup(struct nicvf_rxq *rxq)
 {
 	uintptr_t p;
 	struct rte_mbuf mb_def;
+	struct nicvf *nic = rxq->nic;
 
 	RTE_BUILD_BUG_ON(sizeof(union mbuf_initializer) != 8);
 	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_off) % 8 != 0);
@@ -1240,7 +1243,7 @@ nicvf_rxq_mbuf_setup(struct nicvf_rxq *rxq)
 	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, port) -
 				offsetof(struct rte_mbuf, data_off) != 6);
 	mb_def.nb_segs = 1;
-	mb_def.data_off = RTE_PKTMBUF_HEADROOM;
+	mb_def.data_off = RTE_PKTMBUF_HEADROOM + (nic->skip_bytes);
 	mb_def.port = rxq->port_id;
 	rte_mbuf_refcnt_set(&mb_def, 1);
 
@@ -1260,9 +1263,19 @@ nicvf_dev_rx_queue_setup(struct rte_eth_dev *dev, uint16_t qidx,
 	struct nicvf_rxq *rxq;
 	struct nicvf *nic = nicvf_pmd_priv(dev);
 	uint64_t offloads;
+	uint32_t buffsz;
+	struct rte_pktmbuf_pool_private *mbp_priv;
 
 	PMD_INIT_FUNC_TRACE();
 
+	/* First skip check */
+	mbp_priv = rte_mempool_get_priv(mp);
+	buffsz = mbp_priv->mbuf_data_room_size - RTE_PKTMBUF_HEADROOM;
+	if (buffsz < (uint32_t)(nic->skip_bytes)) {
+		PMD_INIT_LOG(ERR, "First skip is more than configured buffer size");
+		return -EINVAL;
+	}
+
 	if (qidx >= MAX_RCV_QUEUES_PER_QS)
 		nic = nic->snicvf[qidx / MAX_RCV_QUEUES_PER_QS - 1];
 
@@ -1298,6 +1311,7 @@ nicvf_dev_rx_queue_setup(struct rte_eth_dev *dev, uint16_t qidx,
 		return -EINVAL;
 	}
 
+
 	/* Check rx_free_thresh upper bound */
 	rx_free_thresh = (uint16_t)((rx_conf->rx_free_thresh) ?
 				rx_conf->rx_free_thresh :
@@ -1498,6 +1512,7 @@ nicvf_vf_start(struct rte_eth_dev *dev, struct nicvf *nic, uint32_t rbdrsz)
 			return -EINVAL;
 		}
 		rxq->mbuf_phys_off -= data_off;
+		rxq->mbuf_phys_off -= nic->skip_bytes;
 
 		if (mbuf_phys_off == 0)
 			mbuf_phys_off = rxq->mbuf_phys_off;
@@ -1978,6 +1993,59 @@ static const struct eth_dev_ops nicvf_eth_dev_ops = {
 	.get_reg                  = nicvf_dev_get_regs,
 };
 
+static inline int
+nicvf_set_first_skip(struct rte_eth_dev *dev)
+{
+	int bytes_to_skip = 0;
+	int ret = 0;
+	unsigned int i;
+	struct rte_kvargs *kvlist;
+	static const char *const skip[] = {
+		SKIP_DATA_BYTES,
+		NULL};
+	struct nicvf *nic = nicvf_pmd_priv(dev);
+
+	if (!dev->device->devargs) {
+		nicvf_first_skip_config(nic, 0);
+		return ret;
+	}
+
+	kvlist = rte_kvargs_parse(dev->device->devargs->args, skip);
+	if (!kvlist)
+		return -EINVAL;
+
+	if (kvlist->count == 0)
+		goto exit;
+
+	for (i = 0; i != kvlist->count; ++i) {
+		const struct rte_kvargs_pair *pair = &kvlist->pairs[i];
+
+		if (!strcmp(pair->key, SKIP_DATA_BYTES))
+			bytes_to_skip = atoi(pair->value);
+	}
+
+		/*128 bytes amounts to one cache line*/
+	if (bytes_to_skip >= 0 && bytes_to_skip < 128) {
+		if (!(bytes_to_skip % 8)) {
+			nicvf_first_skip_config(nic, (bytes_to_skip / 8));
+			nic->skip_bytes = bytes_to_skip;
+			goto kvlist_free;
+		} else {
+			PMD_INIT_LOG(ERR, "skip_data_bytes should be multiple of 8");
+			ret = -EINVAL;
+			goto exit;
+		}
+	} else {
+		PMD_INIT_LOG(ERR, "skip_data_bytes should be less than 128");
+		ret = -EINVAL;
+		goto exit;
+	}
+exit:
+	nicvf_first_skip_config(nic, 0);
+kvlist_free:
+	rte_kvargs_free(kvlist);
+	return ret;
+}
 static int
 nicvf_eth_dev_init(struct rte_eth_dev *eth_dev)
 {
@@ -2087,6 +2155,11 @@ nicvf_eth_dev_init(struct rte_eth_dev *eth_dev)
 		goto malloc_fail;
 	}
 
+	ret = nicvf_set_first_skip(eth_dev);
+	if (ret) {
+		PMD_INIT_LOG(ERR, "Failed to configure first skip");
+		goto malloc_fail;
+	}
 	PMD_INIT_LOG(INFO, "Port %d (%x:%x) mac=%02x:%02x:%02x:%02x:%02x:%02x",
 		eth_dev->data->port_id, nic->vendor_id, nic->device_id,
 		nic->mac_addr[0], nic->mac_addr[1], nic->mac_addr[2],
@@ -2159,3 +2232,4 @@ static struct rte_pci_driver rte_nicvf_pmd = {
 RTE_PMD_REGISTER_PCI(net_thunderx, rte_nicvf_pmd);
 RTE_PMD_REGISTER_PCI_TABLE(net_thunderx, pci_id_nicvf_map);
 RTE_PMD_REGISTER_KMOD_DEP(net_thunderx, "* igb_uio | uio_pci_generic | vfio-pci");
+RTE_PMD_REGISTER_PARAM_STRING(net_thunderx, SKIP_DATA_BYTES "=<int>");
diff --git a/drivers/net/thunderx/nicvf_ethdev.h b/drivers/net/thunderx/nicvf_ethdev.h
index ea8dccd..9af5088 100644
--- a/drivers/net/thunderx/nicvf_ethdev.h
+++ b/drivers/net/thunderx/nicvf_ethdev.h
@@ -51,6 +51,7 @@
 
 #define VLAN_TAG_SIZE                   4	/* 802.3ac tag */
 
+#define SKIP_DATA_BYTES "skip_data_bytes"
 static inline struct nicvf *
 nicvf_pmd_priv(struct rte_eth_dev *eth_dev)
 {
diff --git a/drivers/net/thunderx/nicvf_struct.h b/drivers/net/thunderx/nicvf_struct.h
index d4a83c3..cf98f7c 100644
--- a/drivers/net/thunderx/nicvf_struct.h
+++ b/drivers/net/thunderx/nicvf_struct.h
@@ -99,6 +99,7 @@ struct nicvf {
 	struct rte_intr_handle intr_handle;
 	uint8_t cpi_alg;
 	uint16_t mtu;
+	int skip_bytes;
 	bool vlan_filter_en;
 	uint8_t mac_addr[ETHER_ADDR_LEN];
 	/* secondary queue set support */
-- 
2.7.4

Re: [dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[Ferruh Yigit]

On 5/28/2018 1:57 PM, rkudurumalla wrote:
> This feature is used to create a hole between HEADROOM
> and actual data.Size of hole is specified in bytes as
> module param to pmd

Can't mbuf private area be used? It is between HEADROOM and mbuf header.

> 
> Signed-off-by: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>

<...>

Re: [dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[Rakesh K]

On Monday 28 May 2018 07:14 PM, Ferruh Yigit wrote:
> On 5/28/2018 1:57 PM, rkudurumalla wrote:
>> This feature is used to create a hole between HEADROOM
>> and actual data.Size of hole is specified in bytes as
>> module param to pmd
> 
> Can't mbuf private area be used? It is between HEADROOM and mbuf header.

data inserted in the hole will be part of the packet data. One of the
use cases is inserting VLAN header for each packet received before it is
being forwarded without having to move the packet data
> 
>>
>> Signed-off-by: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>
> 
> <...>
> 

Re: [dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[Ferruh Yigit]

On 5/30/2018 7:41 AM, Rakesh K wrote:
> 
> 
> On Monday 28 May 2018 07:14 PM, Ferruh Yigit wrote:
>> On 5/28/2018 1:57 PM, rkudurumalla wrote:
>>> This feature is used to create a hole between HEADROOM
>>> and actual data.Size of hole is specified in bytes as
>>> module param to pmd
>>
>> Can't mbuf private area be used? It is between HEADROOM and mbuf header.
> 
> data inserted in the hole will be part of the packet data. One of the
> use cases is inserting VLAN header for each packet received before it is
> being forwarded without having to move the packet data

Cc'ed Olivier.

Is this something should be addressed in mbuf level instead of PMD via devarg?

>>
>>>
>>> Signed-off-by: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>
>>
>> <...>
>>

Re: [dpdk-dev] [PATCH] net/thunderx: add support for hardware first skip feature

[Jerin Jacob]

-----Original Message-----
> Date: Mon, 28 May 2018 18:27:04 +0530
> From: rkudurumalla <rkudurumalla@caviumnetworks.com>
> To: dev@dpdk.org
> CC: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>
> Subject: [dpdk-dev] [PATCH] net/thunderx: add support for hardware first
>  skip feature
> X-Mailer: git-send-email 2.7.4
> 
> This feature is used to create a hole between HEADROOM
> and actual data.Size of hole is specified in bytes as
> module param to pmd
> 
> Signed-off-by: Rakesh Kudurumalla <rkudurumalla@caviumnetworks.com>
> ---
>  doc/guides/nics/thunderx.rst         | 26 ++++++++++++
>  drivers/net/thunderx/base/nicvf_hw.c | 12 ++++++
>  drivers/net/thunderx/base/nicvf_hw.h |  1 +
>  drivers/net/thunderx/nicvf_ethdev.c  | 76 +++++++++++++++++++++++++++++++++++-
>  drivers/net/thunderx/nicvf_ethdev.h  |  1 +
>  drivers/net/thunderx/nicvf_struct.h  |  1 +
>  6 files changed, 116 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/nics/thunderx.rst b/doc/guides/nics/thunderx.rst
> index 2642374..3d68c61 100644
> --- a/doc/guides/nics/thunderx.rst
> +++ b/doc/guides/nics/thunderx.rst
> @@ -30,6 +30,7 @@ Features of the ThunderX PMD are:
>  - SR-IOV VF
>  - NUMA support
>  - Multi queue set support (up to 96 queues (12 queue sets)) per port
> +- First skip support
>  
>  Supported ThunderX SoCs
>  -----------------------
> @@ -312,6 +313,26 @@ We will choose four secondary queue sets from the ending of the list (0002:01:01
>  
>  The nicvf thunderx driver will make use of attached secondary VFs automatically during the interface configuration stage.
>  
> +
> +# Module params
> +
> +    This feature is used to create a hole between HEADROOM and actual data.
> +    Size of hole is specified in bytes as module param to pmd.
> +

This "Module params" comes under "32.6.3. Example device binding", Which
is not correct.

> +Configuration and Options
> +-------------------------

Change the "Configuration and Options" to "Module params" section.

Add sub section called "skip_data_bytes". The above sentence can be
copied here. i.e

---
This feature is used to create a hole between HEADROOM and actual
data.Size of hole is specified in bytes as module
param("skip_data_bytes") to pmd.
This scheme is useful when application would like to 
insert vlan header without disturbing HEADROOM



> +    Use ``-w pci_id,skip_data_bytes="number of bytes to skip"`` in the EAL options
> +    Example:
> +
> +    .. code-block:: console

This section is not rendering correctly.
Please use "make  doc-guides-html" to see the rendered output on the
local PC @ dpdk_dir/build/doc/...


> +
> +    ./your_application -w pci_id=skip_data_bytes=bytes_to_skip
> +
> +    Ex: ./build/app/testpmd -w 0001:01:00.1,skip_data_bytes=8 -- --rxq=1 --txq=1 --nb-cores=1 --port-topology=chained -i -- -c 0x1
> +    This will create a hole of 8 bytes between HEADROOM and actual data.
> +
> +    Use case: The hole created with first_skip can be used to insert vlan header without disturbing HEADROOM

Remove this as it mentioned above.

> +
>  Limitations
>  -----------
>  
> @@ -335,3 +356,8 @@ Maximum packet segments
>  The ThunderX SoC family NICs support up to 12 segments per packet when working
>  in scatter/gather mode. So, setting MTU will result with ``EINVAL`` when the
>  frame size does not fit in the maximum number of segments.
> +
> +First_skip
> +~~~~~~~~~~
> +
> +Maximum limit on first_skip is 128 bytes and number of bytes should be multiple of 8

period(.) is missing at the end.

> diff --git a/drivers/net/thunderx/base/nicvf_hw.c b/drivers/net/thunderx/base/nicvf_hw.c
> index ea8092c..b07a293 100644
> --- a/drivers/net/thunderx/base/nicvf_hw.c
> +++ b/drivers/net/thunderx/base/nicvf_hw.c
> @@ -703,6 +703,18 @@ nicvf_vlan_hw_strip(struct nicvf *nic, bool enable)
>  }
>  
>  void
> +nicvf_first_skip_config(struct nicvf *nic, uint8_t num_dwords)
> +{
> +	uint64_t val;
> +
> +	val = nicvf_reg_read(nic, NIC_VNIC_RQ_GEN_CFG);
> +	val &= ~(0xfULL);
> +	val |= (num_dwords & 0xf);
> +
> +	nicvf_reg_write(nic, NIC_VNIC_RQ_GEN_CFG, val);
> +}
> +
> +void
>  nicvf_apad_config(struct nicvf *nic, bool enable)
>  {
>  	uint64_t val;
> diff --git a/drivers/net/thunderx/base/nicvf_hw.h b/drivers/net/thunderx/base/nicvf_hw.h
> index 284d0bd..fd13ea8 100644
> --- a/drivers/net/thunderx/base/nicvf_hw.h
> +++ b/drivers/net/thunderx/base/nicvf_hw.h
> @@ -193,6 +193,7 @@ uint32_t nicvf_qsize_sq_roundup(uint32_t val);
>  void nicvf_vlan_hw_strip(struct nicvf *nic, bool enable);
>  
>  void nicvf_apad_config(struct nicvf *nic, bool enable);
> +void nicvf_first_skip_config(struct nicvf *nic, uint8_t dwords);
>  
>  int nicvf_rss_config(struct nicvf *nic, uint32_t  qcnt, uint64_t cfg);
>  int nicvf_rss_term(struct nicvf *nic);
> diff --git a/drivers/net/thunderx/nicvf_ethdev.c b/drivers/net/thunderx/nicvf_ethdev.c
> index 99fcd51..466cb86 100644
> --- a/drivers/net/thunderx/nicvf_ethdev.c
> +++ b/drivers/net/thunderx/nicvf_ethdev.c
> @@ -34,6 +34,8 @@
>  #include <rte_pci.h>
>  #include <rte_bus_pci.h>
>  #include <rte_tailq.h>
> +#include <rte_devargs.h>
> +#include <rte_kvargs.h>

add it in alphabetical order.

>  
>  #include "base/nicvf_plat.h"
>  
> @@ -1230,6 +1232,7 @@ nicvf_rxq_mbuf_setup(struct nicvf_rxq *rxq)
>  {
>  	uintptr_t p;
>  	struct rte_mbuf mb_def;
> +	struct nicvf *nic = rxq->nic;
>  
>  	RTE_BUILD_BUG_ON(sizeof(union mbuf_initializer) != 8);
>  	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_off) % 8 != 0);
> @@ -1240,7 +1243,7 @@ nicvf_rxq_mbuf_setup(struct nicvf_rxq *rxq)
>  	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, port) -
>  				offsetof(struct rte_mbuf, data_off) != 6);
>  	mb_def.nb_segs = 1;
> -	mb_def.data_off = RTE_PKTMBUF_HEADROOM;
> +	mb_def.data_off = RTE_PKTMBUF_HEADROOM + (nic->skip_bytes);
>  	mb_def.port = rxq->port_id;
>  	rte_mbuf_refcnt_set(&mb_def, 1);
>  
> @@ -1260,9 +1263,19 @@ nicvf_dev_rx_queue_setup(struct rte_eth_dev *dev, uint16_t qidx,
>  	struct nicvf_rxq *rxq;
>  	struct nicvf *nic = nicvf_pmd_priv(dev);
>  	uint64_t offloads;
> +	uint32_t buffsz;
> +	struct rte_pktmbuf_pool_private *mbp_priv;
>  
>  	PMD_INIT_FUNC_TRACE();
>  
> +	/* First skip check */
> +	mbp_priv = rte_mempool_get_priv(mp);
> +	buffsz = mbp_priv->mbuf_data_room_size - RTE_PKTMBUF_HEADROOM;
> +	if (buffsz < (uint32_t)(nic->skip_bytes)) {
> +		PMD_INIT_LOG(ERR, "First skip is more than configured buffer size");
> +		return -EINVAL;
> +	}
> +
>  	if (qidx >= MAX_RCV_QUEUES_PER_QS)
>  		nic = nic->snicvf[qidx / MAX_RCV_QUEUES_PER_QS - 1];
>  
> @@ -1298,6 +1311,7 @@ nicvf_dev_rx_queue_setup(struct rte_eth_dev *dev, uint16_t qidx,
>  		return -EINVAL;
>  	}
>  
> +
>  	/* Check rx_free_thresh upper bound */
>  	rx_free_thresh = (uint16_t)((rx_conf->rx_free_thresh) ?
>  				rx_conf->rx_free_thresh :
> @@ -1498,6 +1512,7 @@ nicvf_vf_start(struct rte_eth_dev *dev, struct nicvf *nic, uint32_t rbdrsz)
>  			return -EINVAL;
>  		}
>  		rxq->mbuf_phys_off -= data_off;
> +		rxq->mbuf_phys_off -= nic->skip_bytes;
>  
>  		if (mbuf_phys_off == 0)
>  			mbuf_phys_off = rxq->mbuf_phys_off;
> @@ -1978,6 +1993,59 @@ static const struct eth_dev_ops nicvf_eth_dev_ops = {
>  	.get_reg                  = nicvf_dev_get_regs,
>  };
>  
> +static inline int
> +nicvf_set_first_skip(struct rte_eth_dev *dev)
> +{
> +	int bytes_to_skip = 0;
> +	int ret = 0;
> +	unsigned int i;
> +	struct rte_kvargs *kvlist;
> +	static const char *const skip[] = {
> +		SKIP_DATA_BYTES,
> +		NULL};
> +	struct nicvf *nic = nicvf_pmd_priv(dev);
> +
> +	if (!dev->device->devargs) {
> +		nicvf_first_skip_config(nic, 0);
> +		return ret;
> +	}
> +
> +	kvlist = rte_kvargs_parse(dev->device->devargs->args, skip);
> +	if (!kvlist)
> +		return -EINVAL;
> +
> +	if (kvlist->count == 0)
> +		goto exit;
> +
> +	for (i = 0; i != kvlist->count; ++i) {
> +		const struct rte_kvargs_pair *pair = &kvlist->pairs[i];
> +
> +		if (!strcmp(pair->key, SKIP_DATA_BYTES))
> +			bytes_to_skip = atoi(pair->value);
> +	}
> +
> +		/*128 bytes amounts to one cache line*/

Bad comment alignment.

> +	if (bytes_to_skip >= 0 && bytes_to_skip < 128) {
> +		if (!(bytes_to_skip % 8)) {
> +			nicvf_first_skip_config(nic, (bytes_to_skip / 8));
> +			nic->skip_bytes = bytes_to_skip;
> +			goto kvlist_free;
> +		} else {
> +			PMD_INIT_LOG(ERR, "skip_data_bytes should be multiple of 8");
> +			ret = -EINVAL;
> +			goto exit;
> +		}
> +	} else {
> +		PMD_INIT_LOG(ERR, "skip_data_bytes should be less than 128");
> +		ret = -EINVAL;
> +		goto exit;
> +	}
> +exit:
> +	nicvf_first_skip_config(nic, 0);
> +kvlist_free:
> +	rte_kvargs_free(kvlist);
> +	return ret;
> +}
>  static int
>  nicvf_eth_dev_init(struct rte_eth_dev *eth_dev)
>  {
> @@ -2087,6 +2155,11 @@ nicvf_eth_dev_init(struct rte_eth_dev *eth_dev)
>  		goto malloc_fail;
>  	}
>  
> +	ret = nicvf_set_first_skip(eth_dev);
> +	if (ret) {
> +		PMD_INIT_LOG(ERR, "Failed to configure first skip");
> +		goto malloc_fail;
> +	}
>  	PMD_INIT_LOG(INFO, "Port %d (%x:%x) mac=%02x:%02x:%02x:%02x:%02x:%02x",
>  		eth_dev->data->port_id, nic->vendor_id, nic->device_id,
>  		nic->mac_addr[0], nic->mac_addr[1], nic->mac_addr[2],
> @@ -2159,3 +2232,4 @@ static struct rte_pci_driver rte_nicvf_pmd = {
>  RTE_PMD_REGISTER_PCI(net_thunderx, rte_nicvf_pmd);
>  RTE_PMD_REGISTER_PCI_TABLE(net_thunderx, pci_id_nicvf_map);
>  RTE_PMD_REGISTER_KMOD_DEP(net_thunderx, "* igb_uio | uio_pci_generic | vfio-pci");
> +RTE_PMD_REGISTER_PARAM_STRING(net_thunderx, SKIP_DATA_BYTES "=<int>");
> diff --git a/drivers/net/thunderx/nicvf_ethdev.h b/drivers/net/thunderx/nicvf_ethdev.h
> index ea8dccd..9af5088 100644
> --- a/drivers/net/thunderx/nicvf_ethdev.h
> +++ b/drivers/net/thunderx/nicvf_ethdev.h
> @@ -51,6 +51,7 @@
>  
>  #define VLAN_TAG_SIZE                   4	/* 802.3ac tag */
>  
> +#define SKIP_DATA_BYTES "skip_data_bytes"
>  static inline struct nicvf *
>  nicvf_pmd_priv(struct rte_eth_dev *eth_dev)
>  {
> diff --git a/drivers/net/thunderx/nicvf_struct.h b/drivers/net/thunderx/nicvf_struct.h
> index d4a83c3..cf98f7c 100644
> --- a/drivers/net/thunderx/nicvf_struct.h
> +++ b/drivers/net/thunderx/nicvf_struct.h
> @@ -99,6 +99,7 @@ struct nicvf {
>  	struct rte_intr_handle intr_handle;
>  	uint8_t cpi_alg;
>  	uint16_t mtu;
> +	int skip_bytes;

Since the value comes less than 256, use uint8_t

Other that it looks good to me.


>  	bool vlan_filter_en;
>  	uint8_t mac_addr[ETHER_ADDR_LEN];
>  	/* secondary queue set support */
> -- 
> 2.7.4
>