Hi Olivier,
> -----Original Message----- > From: Olivier MATZ [mailto:olivier.matz at 6wind.com] > Sent: Wednesday, December 3, 2014 10:42 PM > To: Ananyev, Konstantin; Liu, Jijiang; dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce > PKT_TX_VXLAN_CKSUM > > Hi Konstantin, > > On 12/03/2014 01:59 PM, Ananyev, Konstantin wrote: > >> 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? > > Yes > > >> 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. > > ok, so we are back between: > > 1/ (Jijiang's patch) > PKT_TX_IP_CKSUM /* packet is IPv4, and we want hw cksum */ > PKT_TX_IPV6 /* packet is IPv6 */ > PKT_TX_IPV4 /* packet is IPv4, and we don't want hw cksum */ > > with PKT_TX_IP_CKSUM and PKT_TX_IPV4 exclusive > > and > > 2/ > PKT_TX_IP_CKSUM /* we want hw IP cksum */ > PKT_TX_IPV6 /* packet is IPv6 */ > PKT_TX_IPV4 /* packet is IPv4 */ > > with PKT_TX_IP_CKSUM implies PKT_TX_IPV4 > > > Solution 2/ looks better from a user point of view. Anyone else has an > opinion? Let's think about these IPv4/6 flags in terms of checksum and IP version/type, 1. For IPv6 IP checksum is meaningful only for IPv4, so we define 'PKT_TX_IPV6 /* packet is IPv6 */' to tell driver/HW that this is IPV6 packet, here we don't talk about the checksum for IPv6 as it is meaningless. Right? PKT_TX_IPV6 /* packet is IPv6 */ ------ IP type: v6; HW checksum: meaningless 2. For IPv4, My patch: PKT_TX_IP_CKSUM /* packet is IPv4, and we want hw cksum */--------------------------IP type: v4; HW checksum: Yes PKT_TX_IPV4 /* packet is IPv4, and we don't want hw cksum */ ----------------------- IP type: v4; HW checksum: No You want: PKT_TX_IP_CKSUM /* we want hw IP cksum */-------------------------- IP type: v4; HW checksum: Yes PKT_TX_IPV4 /* packet is IPv4*/ ------------------------ IP type: v4; HW checksum: yes or no? driver/HW don't know, just know this is packet with IPv4 header. HW checksum: meaningless?? > Regards, > Olivier
