[dpdk-dev] [PATCH 4/6] ethdev: introduce TX common tunnel offloads

[Yongseok Koh]

> On Jan 9, 2018, at 6:11 AM, Xueming Li <xuemingl at mellanox.com> wrote:
> 
> This patch introduce new DEV_TX_OFFLOAD_GENERIC_TNL_CKSUM_TSO flag for
> devices that support tunnel agnostic TX checksum and tso offloading.
> 
> Checksum offset and TSO header length are calculated based on mbuf
> inner length l*_len, outer_l*_len and tx offload flags PKT_TX_*, tunnel
> header length is part of inner l2_len, so device HW do cheksum and TSO
> calculation w/o knowledge of perticular tunnel type.
> 
> When set application must guarantee that correct header types and
> lengths for each inner and outer headers in mbuf header, no need to
> specify tunnel type.
> 
> Signed-off-by: Xueming Li <xuemingl at mellanox.com>
> ---
> lib/librte_ether/rte_ethdev.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
> 
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index 57b61ed41..8457d01be 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1003,6 +1003,15 @@ struct rte_eth_conf {
>  *   the same mempool and has refcnt = 1.
>  */
> #define DEV_TX_OFFLOAD_SECURITY         0x00020000
> +/**< Device supports arbitrary tunnel chksum and tso offloading w/o knowing
> + *   tunnel detail. Checksum and TSO are calculated based on mbuf fields:
> + *     l*_len, outer_l*_len
> + *     PKT_TX_OUTER_IPV6, PKT_TX_IPV6
> + *     PKT_TX_IP_CKSUM, PKT_TX_TCP_CKSUM, PKT_TX_UDP_CKSUM
> + *   When set application must guarantee correct header fields, no need to
> + *   specify tunnel type PKT_TX_TUNNEL_* for HW.
> + */
> +#define DEV_TX_OFFLOAD_GENERIC_TNL_CKSUM_TSO	0x00040000
> 
> struct rte_pci_device;

I'm wondering why generic tunnel offload has to support checksum and TSO
together. Those two are orthogonal, aren't they? App can request HW checksum
offload even for non-TSO packets. Does DEV_TX_OFFLOAD_GENERIC_TNL_CKSUM_TSO mean
HW can support checksum and TSO for generic tunnel? Then shouldn't it be two
flags instead? E.g.
DEV_TX_OFFLOAD_GENERIC_TNL_TSO
DEV_TX_OFFLOAD_GENERIC_TNL_CKSUM

Thanks
Yongseok