[dpdk-dev] [PATCH v2 07/17] mbuf: replace data pointer by an offset

[Olivier Matz <olivier.matz@6wind.com>]

The mbuf structure already contains a pointer to the beginning of the
buffer (m->buf_addr). It is not needed to use 8 bytes again to store
another pointer to the beginning of the data.

Using a 16 bits unsigned integer is enough as we know that a mbuf is
never longer than 64KB. We gain 6 bytes in the structure thanks to
this modification.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 app/test-pmd/csumonly.c               |  2 +-
 app/test-pmd/flowgen.c                |  2 +-
 app/test-pmd/icmpecho.c               |  2 +-
 app/test-pmd/macfwd-retry.c           |  2 +-
 app/test-pmd/macfwd.c                 |  2 +-
 app/test-pmd/macswap.c                |  2 +-
 app/test-pmd/rxonly.c                 |  2 +-
 app/test-pmd/testpmd.c                |  2 +-
 app/test-pmd/txonly.c                 |  7 +++---
 app/test/test_mbuf.c                  |  6 ++---
 examples/exception_path/main.c        |  3 ++-
 examples/vhost/main.c                 | 21 ++++++++++-------
 examples/vhost_xen/main.c             |  2 +-
 lib/librte_mbuf/rte_mbuf.c            |  7 +++---
 lib/librte_mbuf/rte_mbuf.h            | 44 ++++++++++++++++-------------------
 lib/librte_pmd_e1000/em_rxtx.c        | 12 +++++-----
 lib/librte_pmd_e1000/igb_rxtx.c       | 13 +++++------
 lib/librte_pmd_ixgbe/ixgbe_rxtx.c     | 13 ++++++-----
 lib/librte_pmd_ixgbe/ixgbe_rxtx.h     |  3 +--
 lib/librte_pmd_virtio/virtio_rxtx.c   |  2 +-
 lib/librte_pmd_virtio/virtqueue.h     |  5 ++--
 lib/librte_pmd_vmxnet3/vmxnet3_rxtx.c |  5 ++--
 22 files changed, 79 insertions(+), 80 deletions(-)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index ee82eb6..3313b87 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -263,7 +263,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
 		pkt_ol_flags = mb->ol_flags;
 		ol_flags = (uint16_t) (pkt_ol_flags & (~PKT_TX_L4_MASK));
 
-		eth_hdr = (struct ether_hdr *) mb->data;
+		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
 		eth_type = rte_be_to_cpu_16(eth_hdr->ether_type);
 		if (eth_type == ETHER_TYPE_VLAN) {
 			/* Only allow single VLAN label here */
diff --git a/app/test-pmd/flowgen.c b/app/test-pmd/flowgen.c
index 17dbf83..d69b2b8 100644
--- a/app/test-pmd/flowgen.c
+++ b/app/test-pmd/flowgen.c
@@ -175,7 +175,7 @@ pkt_burst_flow_gen(struct fwd_stream *fs)
 		pkt->next = NULL;
 
 		/* Initialize Ethernet header. */
-		eth_hdr = (struct ether_hdr *)pkt->data;
+		eth_hdr = rte_pktmbuf_mtod(pkt, struct ether_hdr *);
 		ether_addr_copy(&cfg_ether_dst, &eth_hdr->d_addr);
 		ether_addr_copy(&cfg_ether_src, &eth_hdr->s_addr);
 		eth_hdr->ether_type = rte_cpu_to_be_16(ETHER_TYPE_IPv4);
diff --git a/app/test-pmd/icmpecho.c b/app/test-pmd/icmpecho.c
index 4a277b8..7fd4b6d 100644
--- a/app/test-pmd/icmpecho.c
+++ b/app/test-pmd/icmpecho.c
@@ -330,7 +330,7 @@ reply_to_icmp_echo_rqsts(struct fwd_stream *fs)
 	nb_replies = 0;
 	for (i = 0; i < nb_rx; i++) {
 		pkt = pkts_burst[i];
-		eth_h = (struct ether_hdr *) pkt->data;
+		eth_h = rte_pktmbuf_mtod(pkt, struct ether_hdr *);
 		eth_type = RTE_BE_TO_CPU_16(eth_h->ether_type);
 		l2_len = sizeof(struct ether_hdr);
 		if (verbose_level > 0) {
diff --git a/app/test-pmd/macfwd-retry.c b/app/test-pmd/macfwd-retry.c
index 687ff8d..7749c9e 100644
--- a/app/test-pmd/macfwd-retry.c
+++ b/app/test-pmd/macfwd-retry.c
@@ -119,7 +119,7 @@ pkt_burst_mac_retry_forward(struct fwd_stream *fs)
 	fs->rx_packets += nb_rx;
 	for (i = 0; i < nb_rx; i++) {
 		mb = pkts_burst[i];
-		eth_hdr = (struct ether_hdr *) mb->data;
+		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
 		ether_addr_copy(&peer_eth_addrs[fs->peer_addr],
 				&eth_hdr->d_addr);
 		ether_addr_copy(&ports[fs->tx_port].eth_addr,
diff --git a/app/test-pmd/macfwd.c b/app/test-pmd/macfwd.c
index 8d7612c..ab74d0c 100644
--- a/app/test-pmd/macfwd.c
+++ b/app/test-pmd/macfwd.c
@@ -110,7 +110,7 @@ pkt_burst_mac_forward(struct fwd_stream *fs)
 	txp = &ports[fs->tx_port];
 	for (i = 0; i < nb_rx; i++) {
 		mb = pkts_burst[i];
-		eth_hdr = (struct ether_hdr *) mb->data;
+		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
 		ether_addr_copy(&peer_eth_addrs[fs->peer_addr],
 				&eth_hdr->d_addr);
 		ether_addr_copy(&ports[fs->tx_port].eth_addr,
diff --git a/app/test-pmd/macswap.c b/app/test-pmd/macswap.c
index 731f487..d274b36 100644
--- a/app/test-pmd/macswap.c
+++ b/app/test-pmd/macswap.c
@@ -110,7 +110,7 @@ pkt_burst_mac_swap(struct fwd_stream *fs)
 	txp = &ports[fs->tx_port];
 	for (i = 0; i < nb_rx; i++) {
 		mb = pkts_burst[i];
-		eth_hdr = (struct ether_hdr *) mb->data;
+		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
 
 		/* Swap dest and src mac addresses. */
 		ether_addr_copy(&eth_hdr->d_addr, &addr);
diff --git a/app/test-pmd/rxonly.c b/app/test-pmd/rxonly.c
index b77c8ce..5751b0b 100644
--- a/app/test-pmd/rxonly.c
+++ b/app/test-pmd/rxonly.c
@@ -149,7 +149,7 @@ pkt_burst_receive(struct fwd_stream *fs)
 			rte_pktmbuf_free(mb);
 			continue;
 		}
-		eth_hdr = (struct ether_hdr *) mb->data;
+		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
 		eth_type = RTE_BE_TO_CPU_16(eth_hdr->ether_type);
 		ol_flags = mb->ol_flags;
 		print_ether_addr("  src=", &eth_hdr->s_addr);
diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index ccbb8bc..92e2729 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -404,7 +404,7 @@ testpmd_mbuf_ctor(struct rte_mempool *mp,
 			mb_ctor_arg->seg_buf_offset);
 	mb->buf_len      = mb_ctor_arg->seg_buf_size;
 	mb->ol_flags     = 0;
-	mb->data         = (char *) mb->buf_addr + RTE_PKTMBUF_HEADROOM;
+	mb->data_off     = RTE_PKTMBUF_HEADROOM;
 	mb->nb_segs      = 1;
 	mb->vlan_macip.data = 0;
 	mb->hash.rss     = 0;
diff --git a/app/test-pmd/txonly.c b/app/test-pmd/txonly.c
index 96c2844..9d6cffb 100644
--- a/app/test-pmd/txonly.c
+++ b/app/test-pmd/txonly.c
@@ -111,13 +111,13 @@ copy_buf_to_pkt_segs(void* buf, unsigned len, struct rte_mbuf *pkt,
 		seg = seg->next;
 	}
 	copy_len = seg->data_len - offset;
-	seg_buf = ((char *) seg->data + offset);
+	seg_buf = (rte_pktmbuf_mtod(seg, char *) + offset);
 	while (len > copy_len) {
 		rte_memcpy(seg_buf, buf, (size_t) copy_len);
 		len -= copy_len;
 		buf = ((char*) buf + copy_len);
 		seg = seg->next;
-		seg_buf = seg->data;
+		seg_buf = rte_pktmbuf_mtod(seg, char *);
 	}
 	rte_memcpy(seg_buf, buf, (size_t) len);
 }
@@ -126,7 +126,8 @@ static inline void
 copy_buf_to_pkt(void* buf, unsigned len, struct rte_mbuf *pkt, unsigned offset)
 {
 	if (offset + len <= pkt->data_len) {
-		rte_memcpy(((char *) pkt->data + offset), buf, (size_t) len);
+		rte_memcpy((rte_pktmbuf_mtod(pkt, char *) + offset),
+			buf, (size_t) len);
 		return;
 	}
 	copy_buf_to_pkt_segs(buf, len, pkt, offset);
diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index 097e75d..ba2f2d9 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -432,7 +432,7 @@ test_pktmbuf_pool_ptr(void)
 			printf("rte_pktmbuf_alloc() failed (%u)\n", i);
 			ret = -1;
 		}
-		m[i]->data = RTE_PTR_ADD(m[i]->data, 64);
+		m[i]->data_off += 64;
 	}
 
 	/* free them */
@@ -451,8 +451,8 @@ test_pktmbuf_pool_ptr(void)
 			printf("rte_pktmbuf_alloc() failed (%u)\n", i);
 			ret = -1;
 		}
-		if (m[i]->data != RTE_PTR_ADD(m[i]->buf_addr, RTE_PKTMBUF_HEADROOM)) {
-			printf ("data pointer not set properly\n");
+		if (m[i]->data_off != RTE_PKTMBUF_HEADROOM) {
+			printf ("invalid data_off\n");
 			ret = -1;
 		}
 	}
diff --git a/examples/exception_path/main.c b/examples/exception_path/main.c
index d9a85b5..ca65511 100644
--- a/examples/exception_path/main.c
+++ b/examples/exception_path/main.c
@@ -302,7 +302,8 @@ main_loop(__attribute__((unused)) void *arg)
 			if (m == NULL)
 				continue;
 
-			ret = read(tap_fd, m->data, MAX_PACKET_SZ);
+			ret = read(tap_fd, rte_pktmbuf_mtod(m, void *),
+				MAX_PACKET_SZ);
 			lcore_stats[lcore_id].rx++;
 			if (unlikely(ret < 0)) {
 				FATAL_ERROR("Reading from %s interface failed",
diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index 26cfc8e..c65f24d 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -815,7 +815,9 @@ virtio_dev_rx(struct virtio_net *dev, struct rte_mbuf **pkts, uint32_t count)
 		vq->used->ring[res_cur_idx & (vq->size - 1)].len = packet_len;
 
 		/* Copy mbuf data to buffer */
-		rte_memcpy((void *)(uintptr_t)buff_addr, (const void*)buff->data, rte_pktmbuf_data_len(buff));
+		rte_memcpy((void *)(uintptr_t)buff_addr,
+			rte_pktmbuf_mtod(buff, const void *),
+			rte_pktmbuf_data_len(buff));
 
 		res_cur_idx++;
 		packet_success++;
@@ -877,7 +879,7 @@ link_vmdq(struct virtio_net *dev, struct rte_mbuf *m)
 	int i, ret;
 
 	/* Learn MAC address of guest device from packet */
-	pkt_hdr = (struct ether_hdr *)m->data;
+	pkt_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
 
 	dev_ll = ll_root_used;
 
@@ -965,7 +967,7 @@ virtio_tx_local(struct virtio_net *dev, struct rte_mbuf *m)
 	struct ether_hdr *pkt_hdr;
 	uint64_t ret = 0;
 
-	pkt_hdr = (struct ether_hdr *)m->data;
+	pkt_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
 
 	/*get the used devices list*/
 	dev_ll = ll_root_used;
@@ -1042,18 +1044,21 @@ virtio_tx_route(struct virtio_net* dev, struct rte_mbuf *m, struct rte_mempool *
 	mbuf->pkt_len = mbuf->data_len;
 
 	/* Copy ethernet header to mbuf. */
-	rte_memcpy((void*)mbuf->data, (const void*)m->data, ETH_HLEN);
+	rte_memcpy(rte_pktmbuf_mtod(mbuf, void *),
+		rte_pktmbuf_mtod(m, const void *),
+		ETH_HLEN);
 
 
 	/* Setup vlan header. Bytes need to be re-ordered for network with htons()*/
-	vlan_hdr = (struct vlan_ethhdr *) mbuf->data;
+	vlan_hdr = rte_pktmbuf_mtod(mbuf, struct vlan_ethhdr *);
 	vlan_hdr->h_vlan_encapsulated_proto = vlan_hdr->h_vlan_proto;
 	vlan_hdr->h_vlan_proto = htons(ETH_P_8021Q);
 	vlan_hdr->h_vlan_TCI = htons(vlan_tag);
 
 	/* Copy the remaining packet contents to the mbuf. */
-	rte_memcpy((void*) ((uint8_t*)mbuf->data + VLAN_ETH_HLEN),
-		(const void*) ((uint8_t*)m->data + ETH_HLEN), (m->data_len - ETH_HLEN));
+	rte_memcpy((void *)(rte_pktmbuf_mtod(mbuf, uint8_t *) + VLAN_ETH_HLEN),
+		(const void *)(rte_pktmbuf_mtod(m, uint8_t *) + ETH_HLEN),
+		(m->data_len - ETH_HLEN));
 	tx_q->m_table[len] = mbuf;
 	len++;
 	if (enable_stats) {
@@ -1144,7 +1149,7 @@ virtio_dev_tx(struct virtio_net* dev, struct rte_mempool *mbuf_pool)
 
 		/* Setup dummy mbuf. This is copied to a real mbuf if transmitted out the physical port. */
 		m.data_len = desc->len;
-		m.data = (void*)(uintptr_t)buff_addr;
+		m.data_off = 0;
 
 		PRINT_PACKET(dev, (uintptr_t)buff_addr, desc->len, 0);
 
diff --git a/examples/vhost_xen/main.c b/examples/vhost_xen/main.c
index 2cf0029..6da1b22 100644
--- a/examples/vhost_xen/main.c
+++ b/examples/vhost_xen/main.c
@@ -981,7 +981,7 @@ virtio_dev_tx(struct virtio_net* dev, struct rte_mempool *mbuf_pool)
 
 		/* Setup dummy mbuf. This is copied to a real mbuf if transmitted out the physical port. */
 		m.data_len = desc->len;
-		m.data = (void*)(uintptr_t)buff_addr;
+		m.data_off = 0;
 		m.nb_segs = 1; 
 
 		virtio_tx_route(dev, &m, mbuf_pool, 0);
diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 9c4077a..e791aa6 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -104,8 +104,7 @@ rte_pktmbuf_init(struct rte_mempool *mp,
 	m->buf_len = (uint16_t)buf_len;
 
 	/* keep some headroom between start of buffer and data */
-	m->data = (char*) m->buf_addr + RTE_MIN(RTE_PKTMBUF_HEADROOM,
-		(uint16_t)m->buf_len);
+	m->data_off = RTE_MIN(RTE_PKTMBUF_HEADROOM, (uint16_t)m->buf_len);
 
 	/* init some constant fields */
 	m->pool = mp;
@@ -171,12 +170,12 @@ rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len)
 		__rte_mbuf_sanity_check(m, 0);
 
 		fprintf(f, "  segment at 0x%p, data=0x%p, data_len=%u\n",
-		       m, m->data, (unsigned)m->data_len);
+			m, rte_pktmbuf_mtod(m, void *), (unsigned)m->data_len);
 		len = dump_len;
 		if (len > m->data_len)
 			len = m->data_len;
 		if (len != 0)
-			rte_hexdump(f, NULL, m->data, len);
+			rte_hexdump(f, NULL, rte_pktmbuf_mtod(m, void *), len);
 		dump_len -= len;
 		m = m->next;
 		nb_segs --;
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 5191eec..cb0a293 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -132,6 +132,13 @@ struct rte_mbuf {
 	void *buf_addr;           /**< Virtual address of segment buffer. */
 	uint64_t buf_physaddr:48; /**< Physical address of segment buffer. */
 	uint64_t buf_len:16;      /**< Length of segment buffer. */
+
+	/* valid for any segment */
+	struct rte_mbuf *next;    /**< Next segment of scattered packet. */
+	uint16_t data_off;
+	uint16_t data_len;        /**< Amount of data in segment buffer. */
+	uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
+
 #ifdef RTE_MBUF_REFCNT
 	/**
 	 * 16-bit Reference counter.
@@ -149,18 +156,11 @@ struct rte_mbuf {
 	uint16_t refcnt_reserved; /**< Do not use this field */
 #endif
 
-	uint16_t ol_flags;        /**< Offload features. */
-	uint32_t reserved;        /**< Unused field. Required for padding. */
-
-	/* valid for any segment */
-	struct rte_mbuf *next;    /**< Next segment of scattered packet. */
-	void* data;               /**< Start address of data in segment. */
-	uint16_t data_len;        /**< Amount of data in segment buffer. */
-
 	/* these fields are valid for first segment only */
 	uint8_t nb_segs;          /**< Number of segments. */
 	uint8_t in_port;          /**< Input port. */
-	uint32_t pkt_len;         /**< Total pkt len: sum of all segments. */
+	uint16_t ol_flags;        /**< Offload features. */
+	uint16_t reserved;        /**< Unused field. Required for padding. */
 
 	/* offload features, valid for first segment only */
 	union rte_vlan_macip vlan_macip;
@@ -172,6 +172,7 @@ struct rte_mbuf {
 		} fdir;           /**< Filter identifier if FDIR enabled */
 		uint32_t sched;   /**< Hierarchical scheduler */
 	} hash;                   /**< hash information */
+	uint64_t reserved2;       /**< Unused field. Required for padding. */
 } __rte_cache_aligned;
 
 /**
@@ -436,8 +437,6 @@ void rte_pktmbuf_pool_init(struct rte_mempool *mp, void *opaque_arg);
  */
 static inline void rte_pktmbuf_reset(struct rte_mbuf *m)
 {
-	uint32_t buf_ofs;
-
 	m->next = NULL;
 	m->pkt_len = 0;
 	m->vlan_macip.data = 0;
@@ -445,9 +444,8 @@ static inline void rte_pktmbuf_reset(struct rte_mbuf *m)
 	m->in_port = 0xff;
 
 	m->ol_flags = 0;
-	buf_ofs = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
+	m->data_off = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
 			RTE_PKTMBUF_HEADROOM : m->buf_len;
-	m->data = (char*) m->buf_addr + buf_ofs;
 
 	m->data_len = 0;
 	__rte_mbuf_sanity_check(m, 1);
@@ -504,7 +502,7 @@ static inline void rte_pktmbuf_attach(struct rte_mbuf *mi, struct rte_mbuf *md)
 	mi->buf_len = md->buf_len;
 
 	mi->next = md->next;
-	mi->data = md->data;
+	mi->data_off = md->data_off;
 	mi->data_len = md->data_len;
 	mi->in_port = md->in_port;
 	mi->vlan_macip = md->vlan_macip;
@@ -533,16 +531,14 @@ static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
 {
 	const struct rte_mempool *mp = m->pool;
 	void *buf = RTE_MBUF_TO_BADDR(m);
-	uint32_t buf_ofs;
 	uint32_t buf_len = mp->elt_size - sizeof(*m);
 	m->buf_physaddr = rte_mempool_virt2phy(mp, m) + sizeof (*m);
 
 	m->buf_addr = buf;
 	m->buf_len = (uint16_t)buf_len;
 
-	buf_ofs = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
+	m->data_off = (RTE_PKTMBUF_HEADROOM <= m->buf_len) ?
 			RTE_PKTMBUF_HEADROOM : m->buf_len;
-	m->data = (char*) m->buf_addr + buf_ofs;
 
 	m->data_len = 0;
 }
@@ -706,7 +702,7 @@ static inline void rte_pktmbuf_refcnt_update(struct rte_mbuf *m, int16_t v)
 static inline uint16_t rte_pktmbuf_headroom(const struct rte_mbuf *m)
 {
 	__rte_mbuf_sanity_check(m, 1);
-	return (uint16_t) ((char*) m->data - (char*) m->buf_addr);
+	return m->data_off;
 }
 
 /**
@@ -754,7 +750,7 @@ static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m)
  * @param t
  *   The type to cast the result into.
  */
-#define rte_pktmbuf_mtod(m, t) ((t)((m)->data))
+#define rte_pktmbuf_mtod(m, t) ((t)((char *)(m)->buf_addr + (m)->data_off))
 
 /**
  * A macro that returns the length of the packet.
@@ -799,11 +795,11 @@ static inline char *rte_pktmbuf_prepend(struct rte_mbuf *m,
 	if (unlikely(len > rte_pktmbuf_headroom(m)))
 		return NULL;
 
-	m->data = (char*) m->data - len;
+	m->data_off -= len;
 	m->data_len = (uint16_t)(m->data_len + len);
 	m->pkt_len  = (m->pkt_len + len);
 
-	return (char*) m->data;
+	return (char*) m->buf_addr + m->data_off;
 }
 
 /**
@@ -832,7 +828,7 @@ static inline char *rte_pktmbuf_append(struct rte_mbuf *m, uint16_t len)
 	if (unlikely(len > rte_pktmbuf_tailroom(m_last)))
 		return NULL;
 
-	tail = (char*) m_last->data + m_last->data_len;
+	tail = (char*) m_last->buf_addr + m_last->data_off + m_last->data_len;
 	m_last->data_len = (uint16_t)(m_last->data_len + len);
 	m->pkt_len  = (m->pkt_len + len);
 	return (char*) tail;
@@ -860,9 +856,9 @@ static inline char *rte_pktmbuf_adj(struct rte_mbuf *m, uint16_t len)
 		return NULL;
 
 	m->data_len = (uint16_t)(m->data_len - len);
-	m->data = ((char*) m->data + len);
+	m->data_off += len;
 	m->pkt_len  = (m->pkt_len - len);
-	return (char*) m->data;
+	return (char *)m->buf_addr + m->data_off;
 }
 
 /**
diff --git a/lib/librte_pmd_e1000/em_rxtx.c b/lib/librte_pmd_e1000/em_rxtx.c
index ea72fe3..8c302b6 100644
--- a/lib/librte_pmd_e1000/em_rxtx.c
+++ b/lib/librte_pmd_e1000/em_rxtx.c
@@ -90,8 +90,7 @@ rte_rxmbuf_alloc(struct rte_mempool *mp)
 }
 
 #define RTE_MBUF_DATA_DMA_ADDR(mb)             \
-	(uint64_t) ((mb)->buf_physaddr +       \
-	(uint64_t) ((char *)((mb)->data) - (char *)(mb)->buf_addr))
+	(uint64_t) ((mb)->buf_physaddr + (mb)->data_off)
 
 #define RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mb) \
 	(uint64_t) ((mb)->buf_physaddr + RTE_PKTMBUF_HEADROOM)
@@ -771,8 +770,8 @@ eth_em_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		pkt_len = (uint16_t) (rte_le_to_cpu_16(rxd.length) -
 				rxq->crc_len);
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
-		rte_packet_prefetch(rxm->data);
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
+		rte_packet_prefetch((char *)rxm->buf_addr + rxm->data_off);
 		rxm->nb_segs = 1;
 		rxm->next = NULL;
 		rxm->pkt_len = pkt_len;
@@ -941,7 +940,7 @@ eth_em_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		data_len = rte_le_to_cpu_16(rxd.length);
 		rxm->data_len = data_len;
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
 
 		/*
 		 * If this is the first buffer of the received packet,
@@ -1013,7 +1012,8 @@ eth_em_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		rxm->vlan_macip.f.vlan_tci = rte_le_to_cpu_16(rxd.special);
 
 		/* Prefetch data of first segment, if configured to do so. */
-		rte_packet_prefetch(first_seg->data);
+		rte_packet_prefetch((char *)first_seg->buf_addr +
+			first_seg->data_off);
 
 		/*
 		 * Store the mbuf address into the next entry of the array
diff --git a/lib/librte_pmd_e1000/igb_rxtx.c b/lib/librte_pmd_e1000/igb_rxtx.c
index da33171..ab0ff01 100644
--- a/lib/librte_pmd_e1000/igb_rxtx.c
+++ b/lib/librte_pmd_e1000/igb_rxtx.c
@@ -84,9 +84,7 @@ rte_rxmbuf_alloc(struct rte_mempool *mp)
 }
 
 #define RTE_MBUF_DATA_DMA_ADDR(mb) \
-	(uint64_t) ((mb)->buf_physaddr +		   \
-			(uint64_t) ((char *)((mb)->data) -     \
-				(char *)(mb)->buf_addr))
+	(uint64_t) ((mb)->buf_physaddr + (mb)->data_off)
 
 #define RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mb) \
 	(uint64_t) ((mb)->buf_physaddr + RTE_PKTMBUF_HEADROOM)
@@ -742,8 +740,8 @@ eth_igb_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		pkt_len = (uint16_t) (rte_le_to_cpu_16(rxd.wb.upper.length) -
 				      rxq->crc_len);
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
-		rte_packet_prefetch(rxm->data);
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
+		rte_packet_prefetch((char *)rxm->buf_addr + rxm->data_off);
 		rxm->nb_segs = 1;
 		rxm->next = NULL;
 		rxm->pkt_len = pkt_len;
@@ -919,7 +917,7 @@ eth_igb_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		data_len = rte_le_to_cpu_16(rxd.wb.upper.length);
 		rxm->data_len = data_len;
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
 
 		/*
 		 * If this is the first buffer of the received packet,
@@ -1001,7 +999,8 @@ eth_igb_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		first_seg->ol_flags = pkt_flags;
 
 		/* Prefetch data of first segment, if configured to do so. */
-		rte_packet_prefetch(first_seg->data);
+		rte_packet_prefetch((char *)first_seg->buf_addr +
+			first_seg->data_off);
 
 		/*
 		 * Store the mbuf address into the next entry of the array
diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
index 1f95f30..acde64b 100644
--- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
+++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
@@ -988,7 +988,7 @@ ixgbe_rx_alloc_bufs(struct igb_rx_queue *rxq)
 		mb = rxep[i].mbuf;
 		rte_mbuf_refcnt_set(mb, 1);
 		mb->next = NULL;
-		mb->data = (char *)mb->buf_addr + RTE_PKTMBUF_HEADROOM;
+		mb->data_off = RTE_PKTMBUF_HEADROOM;
 		mb->nb_segs = 1;
 		mb->in_port = rxq->port_id;
 
@@ -1239,8 +1239,8 @@ ixgbe_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		pkt_len = (uint16_t) (rte_le_to_cpu_16(rxd.wb.upper.length) -
 				      rxq->crc_len);
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
-		rte_packet_prefetch(rxm->data);
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
+		rte_packet_prefetch((char *)rxm->buf_addr + rxm->data_off);
 		rxm->nb_segs = 1;
 		rxm->next = NULL;
 		rxm->pkt_len = pkt_len;
@@ -1423,7 +1423,7 @@ ixgbe_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		 */
 		data_len = rte_le_to_cpu_16(rxd.wb.upper.length);
 		rxm->data_len = data_len;
-		rxm->data = (char*) rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
 
 		/*
 		 * If this is the first buffer of the received packet,
@@ -1515,7 +1515,8 @@ ixgbe_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		}
 
 		/* Prefetch data of first segment, if configured to do so. */
-		rte_packet_prefetch(first_seg->data);
+		rte_packet_prefetch((char *)first_seg->buf_addr + 
+			first_seg->data_off);
 
 		/*
 		 * Store the mbuf address into the next entry of the array
@@ -3084,7 +3085,7 @@ ixgbe_alloc_rx_queue_mbufs(struct igb_rx_queue *rxq)
 
 		rte_mbuf_refcnt_set(mbuf, 1);
 		mbuf->next = NULL;
-		mbuf->data = (char *)mbuf->buf_addr + RTE_PKTMBUF_HEADROOM;
+		mbuf->data_off = RTE_PKTMBUF_HEADROOM;
 		mbuf->nb_segs = 1;
 		mbuf->in_port = rxq->port_id;
 
diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
index b959c9b..8cf66bf 100644
--- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
+++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
@@ -45,8 +45,7 @@
 #endif
 
 #define RTE_MBUF_DATA_DMA_ADDR(mb) \
-	(uint64_t) ((mb)->buf_physaddr + (uint64_t)((char *)((mb)->data) - \
-	(char *)(mb)->buf_addr))
+	(uint64_t) ((mb)->buf_physaddr + (mb)->data_off)
 
 #define RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mb) \
 	(uint64_t) ((mb)->buf_physaddr + RTE_PKTMBUF_HEADROOM)
diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c b/lib/librte_pmd_virtio/virtio_rxtx.c
index 2af2c49..835e277 100644
--- a/lib/librte_pmd_virtio/virtio_rxtx.c
+++ b/lib/librte_pmd_virtio/virtio_rxtx.c
@@ -268,7 +268,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 			continue;
 		}
 		rxm->in_port = rxvq->port_id;
-		rxm->data = (char *)rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
+		rxm->data_off = RTE_PKTMBUF_HEADROOM;
 		rxm->nb_segs = 1;
 		rxm->next = NULL;
 		rxm->pkt_len  = (uint32_t)(len[i] - sizeof(struct virtio_net_hdr));
diff --git a/lib/librte_pmd_virtio/virtqueue.h b/lib/librte_pmd_virtio/virtqueue.h
index 210944e..11f908c 100644
--- a/lib/librte_pmd_virtio/virtqueue.h
+++ b/lib/librte_pmd_virtio/virtqueue.h
@@ -59,8 +59,7 @@
 #define VIRTQUEUE_MAX_NAME_SZ 32
 
 #define RTE_MBUF_DATA_DMA_ADDR(mb) \
-	(uint64_t) ((mb)->buf_physaddr + (uint64_t)((char *)((mb)->data) - \
-	(char *)(mb)->buf_addr))
+	(uint64_t) ((mb)->buf_physaddr + (mb)->data_off)
 
 #define VTNET_SQ_RQ_QUEUE_IDX 0
 #define VTNET_SQ_TQ_QUEUE_IDX 1
@@ -363,7 +362,7 @@ virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts, uint
 			break;
 		}
 		rte_prefetch0(cookie);
-		rte_packet_prefetch(cookie->data);
+		rte_packet_prefetch((char *)cookie->buf_addr + cookie->data_off);
 		rx_pkts[i]  = cookie;
 		vq->vq_used_cons_idx++;
 		vq_ring_free_chain(vq, desc_idx);
diff --git a/lib/librte_pmd_vmxnet3/vmxnet3_rxtx.c b/lib/librte_pmd_vmxnet3/vmxnet3_rxtx.c
index 6db766a..0845b1d 100644
--- a/lib/librte_pmd_vmxnet3/vmxnet3_rxtx.c
+++ b/lib/librte_pmd_vmxnet3/vmxnet3_rxtx.c
@@ -80,8 +80,7 @@
 
 
 #define RTE_MBUF_DATA_DMA_ADDR(mb) \
-	(uint64_t) ((mb)->buf_physaddr + (uint64_t)((char *)((mb)->data) - \
-	(char *)(mb)->buf_addr))
+	(uint64_t) ((mb)->buf_physaddr + (mb)->data_off)
 
 #define RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mb) \
 	(uint64_t) ((mb)->buf_physaddr + RTE_PKTMBUF_HEADROOM)
@@ -551,7 +550,7 @@ vmxnet3_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 			rxm->data_len = (uint16_t)rcd->len;
 			rxm->in_port = rxq->port_id;
 			rxm->vlan_macip.f.vlan_tci = 0;
-			rxm->data = (char *)rxm->buf_addr + RTE_PKTMBUF_HEADROOM;
+			rxm->data_off = RTE_PKTMBUF_HEADROOM;
 
 			rx_pkts[nb_rx++] = rxm;
 
-- 
1.9.2