[dpdk-dev] [PATCH] net/thunderx: check data offset alignment requirement

[Hemant Agrawal]

On 3/4/2017 6:16 PM, Jerin Jacob wrote:
> nicvf HW expects the DMA address of the packet data to be
> aligned with cache line size.
>
> Packet data offset is a function of struct mbuf size,
> mbuf private size and headroom. mbuf private size can
> be changed from the application in pool creation, this
> check detects HW alignment requirement constraint in pmd
> start function.
>
> Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> ---
>  drivers/net/thunderx/nicvf_ethdev.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/thunderx/nicvf_ethdev.c b/drivers/net/thunderx/nicvf_ethdev.c
> index 1060319..ad7b5d6 100644
> --- a/drivers/net/thunderx/nicvf_ethdev.c
> +++ b/drivers/net/thunderx/nicvf_ethdev.c
> @@ -1410,7 +1410,7 @@ static int
>  nicvf_vf_start(struct rte_eth_dev *dev, struct nicvf *nic, uint32_t rbdrsz)
>  {
>  	int ret;
> -	uint16_t qidx;
> +	uint16_t qidx, data_off;
>  	uint32_t total_rxq_desc, nb_rbdr_desc, exp_buffs;
>  	uint64_t mbuf_phys_off = 0;
>  	struct nicvf_rxq *rxq;
> @@ -1451,10 +1451,17 @@ nicvf_vf_start(struct rte_eth_dev *dev, struct nicvf *nic, uint32_t rbdrsz)
>  				     nic->vf_id, qidx, rxq->pool->name);
>  			return -ENOMEM;
>  		}
> -		rxq->mbuf_phys_off -= nicvf_mbuff_meta_length(mbuf);
> -		rxq->mbuf_phys_off -= RTE_PKTMBUF_HEADROOM;
> +		data_off = nicvf_mbuff_meta_length(mbuf);
> +		data_off += RTE_PKTMBUF_HEADROOM;
>  		rte_pktmbuf_free(mbuf);
>
> +		if (data_off % RTE_CACHE_LINE_SIZE) {
> +			PMD_INIT_LOG(ERR, "unaligned data_offset=%d delta=%d\n",
> +				data_off, data_off % RTE_CACHE_LINE_SIZE);

Do you also want to log about the particular pool having this issue?
rxq->pool->name

> +			return -EINVAL;
> +		}
> +		rxq->mbuf_phys_off -= data_off;
> +
>  		if (mbuf_phys_off == 0)
>  			mbuf_phys_off = rxq->mbuf_phys_off;
>  		if (mbuf_phys_off != rxq->mbuf_phys_off) {
>
otherwise, you may add:
Acked-by: Hemant Agrawal <hemant.agrawal at nxp.com>