Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Oliver,

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier MATZ
> Sent: Wednesday, December 03, 2014 11:41 AM
> To: Liu, Jijiang; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM
> 
> Hi Jijiang,
> 
> On 12/02/2014 04:06 PM, Jijiang Liu wrote:
> > Replace PKT_TX_VXLAN_CKSUM with PKT_TX_UDP_TUNNEL_PKT in order to indicate a packet is an UDP tunneling packet, and
> introduce 3 TX offload flags for outer IP TX checksum, which are PKT_TX_OUTER_IP_CKSUM, PKT_TX_OUTER_IPV4 and
> PKT_TX_OUTER_IPV6 respectively;Rework csum forward engine and i40e PMD due to these changes.
> >
> > Signed-off-by: Jijiang Liu <jijiang.liu@intel.com>
> > ---
> >   app/test-pmd/csumonly.c         |    9 +++++++--
> >   lib/librte_mbuf/rte_mbuf.c      |    7 ++++++-
> >   lib/librte_mbuf/rte_mbuf.h      |   11 ++++++++++-
> >   lib/librte_pmd_i40e/i40e_rxtx.c |    6 +++---
> >   4 files changed, 26 insertions(+), 7 deletions(-)
> >
> > diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
> > index d8c080a..9094967 100644
> > --- a/app/test-pmd/csumonly.c
> > +++ b/app/test-pmd/csumonly.c
> > @@ -257,7 +257,7 @@ process_outer_cksums(void *outer_l3_hdr, uint16_t outer_ethertype,
> >   	uint64_t ol_flags = 0;
> >
> >   	if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> > -		ol_flags |= PKT_TX_VXLAN_CKSUM;
> > +		ol_flags |= PKT_TX_UDP_TUNNEL_PKT;
> >
> >   	if (outer_ethertype == _htons(ETHER_TYPE_IPv4)) {
> >   		ipv4_hdr->hdr_checksum = 0;
> > @@ -470,7 +470,12 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> >   				{ PKT_TX_UDP_CKSUM, PKT_TX_L4_MASK },
> >   				{ PKT_TX_TCP_CKSUM, PKT_TX_L4_MASK },
> >   				{ PKT_TX_SCTP_CKSUM, PKT_TX_L4_MASK },
> > -				{ PKT_TX_VXLAN_CKSUM, PKT_TX_VXLAN_CKSUM },
> > +				{ PKT_TX_UDP_TUNNEL_PKT, PKT_TX_UDP_TUNNEL_PKT },
> > +				{ PKT_TX_IPV4, PKT_TX_IPV4 },
> > +				{ PKT_TX_IPV6, PKT_TX_IPV6 },
> > +				{ PKT_TX_OUTER_IP_CKSUM, PKT_TX_OUTER_IP_CKSUM },
> > +				{ PKT_TX_OUTER_IPV4, PKT_TX_OUTER_IPV4 },
> > +				{ PKT_TX_OUTER_IPV6, PKT_TX_OUTER_IPV6 },
> >   				{ PKT_TX_TCP_SEG, PKT_TX_TCP_SEG },
> 
> I still think having a flag IPV4 + another flag IP_CHECKSUM is not
> appropriate.

Sorry, didn't get you here.
Are you talking about our discussion should PKT_TX_IP_CKSUM and PKT_TX_IPV4 be mutually exclusive or not?

> I though Konstantin agreed on other flags, but I may
> have misunderstood:
> 
> http://dpdk.org/ml/archives/dev/2014-November/009070.html

In that mail, I was talking about my suggestion to make  PKT_TX_IP_CKSUM, PKT_TX_IPV4 and PKT_TX_IPV6 to occupy 2 bits.
Something like:
#define	PKT_TX_IP_CKSUM	(1 << X)
#define	PKT_TX_IPV6		(2 << X)
#define 	PKT_TX_IPV4		(3 << X)

"Even better, if we can squeeze these 3 flags into 2 bits.
Would save us 2 bits, plus might be handy, as in the PMD you can do:

switch (ol_flags & TX_L3_MASK) {
    case TX_IPV4:
       ...
       break;
    case TX_IPV6:
       ...
       break;
    case TX_IP_CKSUM:
       ...
       break;
}"

As you pointed out, it will break backward compatibility.
I agreed with that and self-NACKed it.

> 
> 
> Olivier