[dpdk-dev] [PATCH] e1000: fix the issue of wrongly reporting descriptor done

[dpdk-dev] [PATCH] e1000: fix the issue of wrongly reporting descriptor done

[Wenzhuo Lu]

Header buffer address for header split will be filled with the physical
address for DMA, which is actually not needed at all, as header split
hasn't been supported. Hardware requires the least bit of header address
which is 'Descriptor Done' bit when write back should be set to 0 by driver.
The issue is that if the user wants to reserve an odd number of bytes between
the mbuf header and data buffer, the physical address to be filled in the
descriptor would happen to be odd. That means the DD bit would be set to
non-zero by driver. That will result in reporting descriptor done wrongly.

Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
---
 drivers/net/e1000/igb_rxtx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/e1000/igb_rxtx.c b/drivers/net/e1000/igb_rxtx.c
index 3a31b21..b13930e 100644
--- a/drivers/net/e1000/igb_rxtx.c
+++ b/drivers/net/e1000/igb_rxtx.c
@@ -851,7 +851,7 @@ eth_igb_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		rxe->mbuf = nmb;
 		dma_addr =
 			rte_cpu_to_le_64(RTE_MBUF_DATA_DMA_ADDR_DEFAULT(nmb));
-		rxdp->read.hdr_addr = dma_addr;
+		rxdp->read.hdr_addr = 0;
 		rxdp->read.pkt_addr = dma_addr;
 
 		/*
@@ -1040,7 +1040,7 @@ eth_igb_recv_scattered_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		rxe->mbuf = nmb;
 		dma = rte_cpu_to_le_64(RTE_MBUF_DATA_DMA_ADDR_DEFAULT(nmb));
 		rxdp->read.pkt_addr = dma;
-		rxdp->read.hdr_addr = dma;
+		rxdp->read.hdr_addr = 0;
 
 		/*
 		 * Set data length & data buffer address of mbuf.
@@ -1990,7 +1990,7 @@ igb_alloc_rx_queue_mbufs(struct igb_rx_queue *rxq)
 		dma_addr =
 			rte_cpu_to_le_64(RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mbuf));
 		rxd = &rxq->rx_ring[i];
-		rxd->read.hdr_addr = dma_addr;
+		rxd->read.hdr_addr = 0;
 		rxd->read.pkt_addr = dma_addr;
 		rxe[i].mbuf = mbuf;
 	}
-- 
1.9.3

Re: [dpdk-dev] [PATCH] e1000: fix the issue of wrongly reporting descriptor done

[Thomas Monjalon]

2015-07-30 10:39, Wenzhuo Lu:
> Header buffer address for header split will be filled with the physical
> address for DMA, which is actually not needed at all, as header split
> hasn't been supported. Hardware requires the least bit of header address
> which is 'Descriptor Done' bit when write back should be set to 0 by driver.
> The issue is that if the user wants to reserve an odd number of bytes between
> the mbuf header and data buffer, the physical address to be filled in the
> descriptor would happen to be odd. That means the DD bit would be set to
> non-zero by driver. That will result in reporting descriptor done wrongly.
> 
> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>

Applied, thanks