Re: [PATCH 04/12] mbuf: add help about TX checksum flags

[Bruce Richardson <bruce.richardson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Mon, Nov 10, 2014 at 04:59:18PM +0100, Olivier Matz wrote:
> Describe how to use hardware checksum API.
> 
> Signed-off-by: Olivier Matz <olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>

Acked-by: Bruce Richardson <bruce.richardson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

> ---
>  lib/librte_mbuf/rte_mbuf.h | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index be15168..96e322b 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -95,19 +95,28 @@ extern "C" {
>  #define PKT_RX_TUNNEL_IPV6_HDR (1ULL << 12) /**< RX tunnel packet with IPv6 header. */
>  
>  #define PKT_TX_VLAN_PKT      (1ULL << 55) /**< TX packet is a 802.1q VLAN packet. */
> -#define PKT_TX_IP_CKSUM      (1ULL << 54) /**< IP cksum of TX pkt. computed by NIC. */
> +
> +/**
> + * Enable hardware computation of IP cksum. To use it:
> + *  - fill l2_len and l3_len in mbuf
> + *  - set the flags PKT_TX_IP_CKSUM
> + *  - set the ip checksum to 0 in IP header
> + */
> +#define PKT_TX_IP_CKSUM      (1ULL << 54)
>  #define PKT_TX_IPV4_CSUM     PKT_TX_IP_CKSUM /**< Alias of PKT_TX_IP_CKSUM. */
>  #define PKT_TX_IPV4          PKT_RX_IPV4_HDR /**< IPv4 with no IP checksum offload. */
>  #define PKT_TX_IPV6          PKT_RX_IPV6_HDR /**< IPv6 packet */
>  
> -/*
> - * Bits 52+53 used for L4 packet type with checksum enabled.
> - *     00: Reserved
> - *     01: TCP checksum
> - *     10: SCTP checksum
> - *     11: UDP checksum
> +/**
> + * Bits 52+53 used for L4 packet type with checksum enabled: 00: Reserved,
> + * 01: TCP checksum, 10: SCTP checksum, 11: UDP checksum. To use hardware
> + * L4 checksum offload, the user needs to:
> + *  - fill l2_len and l3_len in mbuf
> + *  - set the flags PKT_TX_TCP_CKSUM, PKT_TX_SCTP_CKSUM or PKT_TX_UDP_CKSUM
> + *  - calculate the pseudo header checksum and set it in the L4 header (only
> + *    for TCP or UDP). For SCTP, set the crc field to 0.
>   */
> -#define PKT_TX_L4_NO_CKSUM   (0ULL << 52) /**< Disable L4 cksum of TX pkt. */
> +#define PKT_TX_L4_NO_CKSUM   (0ULL << 52) /* Disable L4 cksum of TX pkt. */
>  #define PKT_TX_TCP_CKSUM     (1ULL << 52) /**< TCP cksum of TX pkt. computed by NIC. */
>  #define PKT_TX_SCTP_CKSUM    (2ULL << 52) /**< SCTP cksum of TX pkt. computed by NIC. */
>  #define PKT_TX_UDP_CKSUM     (3ULL << 52) /**< UDP cksum of TX pkt. computed by NIC. */
> -- 
> 2.1.0
>