From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH v5 2/3] mbuf:add three TX ol_flags and repalce PKT_TX_VXLAN_CKSUM Date: Thu, 04 Dec 2014 11:45:14 +0100 Message-ID: <2324692.x6b6svf072@xps13> References: <1417532767-1309-1-git-send-email-jijiang.liu@intel.com> <1ED644BD7E0A5F4091CF203DAFB8E4CC01D9FF2B@SHSMSX101.ccr.corp.intel.com> <2601191342CEEE43887BDE71AB977258213BC6F2@IRSMSX105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev-VfR2kkLFssw@public.gmane.org To: "Ananyev, Konstantin" , Olivier MATZ Return-path: In-Reply-To: <2601191342CEEE43887BDE71AB977258213BC6F2-kPTMFJFq+rEu0RiL9chJVbfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Hi, 2014-12-04 10:23, Ananyev, Konstantin: > From: Liu, Jijiang > > From: Olivier MATZ [mailto:olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org] > > > 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?? > > Yep, that's why I also don't like that suggestion: PKT_TX_IPV4 itself doesn't contain all information. > PMD will have to check PKT_TX_IP_CKSUM anyway. I prefer solution 2 because a flag should bring only 1 information. It's simply saner and could fit to more situations in the future. -- Thomas