[dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and csum forwarding engine

[Liu, Jijiang]

Hi Konstantin,

> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Wednesday, January 7, 2015 5:59 PM
> To: Liu, Jijiang; 'Olivier MATZ'
> Cc: dev at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and
> csum forwarding engine
> 
> Hi Frank,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Liu, Jijiang
> > Sent: Wednesday, January 07, 2015 2:04 AM
> > To: 'Olivier MATZ'
> > Cc: dev at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v3 0/3] enhance TX checksum command and
> > csum forwarding engine
> >
> > Hi Olivier,
> >
> > > -----Original Message-----
> > > From: Olivier MATZ [mailto:olivier.matz at 6wind.com]
> > > Sent: Saturday, December 13, 2014 12:33 AM
> > > To: Liu, Jijiang
> > > Cc: dev at dpdk.org
> > > Subject: Re: [dpdk-dev] [PATCH v3 0/3] enhance TX checksum command
> > > and csum forwarding engine
> > >
> > > Hello,
> > >
> > > On 12/12/2014 04:48 AM, Liu, Jijiang wrote:
> > > > The 'hw/sw' option  is used to set/clear the flag of enabling TX
> > > > tunneling packet
> > > checksum hardware offload in testpmd application.
> > >
> > > This is not clear at all.
> > > In your command, there is (hw|sw|none).
> > > Are you talking about inner or outer?
> > > Is this command useful for any kind of packet?
> > > How does it combine with "tx_checksum set outer-ip (hw|sw)"?
> > >
> >
> > I rethink these TX checksum commands in this patch set and agree with
> > you that we should make some changes for having clear meaning for them.
> >
> > There are  3 commands in patch set as follows, 1. tx_checksum set
> > tunnel (hw|sw|none) (port-id)
> >
> > Now I also think the command 1 may confuse user, they probably don't
> > understand  why we need 'hw' or 'sw' option and when  to use the two
> > option, so I will replace the command with 'tx_checksum set hw-tunnel-mode
> (on|off) (port-id)' command.
> 
> I am a bit confused here, could you explain what would be a behaviour for 'on' and
> 'off'?
> Konstantin

I have explained the behaviour for 'on' and'off' below,

The command 'tx_checksum set hw-tunnel-mode (on|off)  (port-id)' is 
used to set/clear  TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM flag.

Actually, the PKT_TX_UDP_TUNNEL_PKT offload flag will be set if the 
testpmd flag is set, which means to tell HW treat  that transmit packet as a tunneling packet to do checksum offload
 When 'on' is set, which is able to meet Method B.1 and method C.

When 'off' is set, the TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM is not needed 
to set, so the PKT_TX_UDP_TUNNEL_PKT offload flag is not needed to set,  then HW treat  that transmit packet as a non-tunneling packet. It is able to meet Method B.2.

Is the explanation not clear?

>
> >
> > 2. tx_checksum set outer-ip (hw|sw) (port-id) 3. tx_checksum set
> > (ip|udp|tcp|sctp) (hw|sw) (port-id)
> >
> > The command 2 will be merged into command 3, the new command is '
> > tx_checksum set  (outer-ip|ip|udp|tcp|sctp) (hw|sw) (port- id)'.
> >
> > These most of the cases in
> > http://dpdk.org/ml/archives/dev/2014-December/009213.html will be
> > covered by using the two commands
> >
> > The command 'tx_checksum set hw-tunnel-mode (on|off)  (port-id)' is
> > used to set/clear  TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM flag.
> > Actually, the PKT_TX_UDP_TUNNEL_PKT offload flag will be set if the
> > testpmd flag is set, which tell driver/HW treat  that transmit packet as a
> tunneling packet.
> >
> > When 'on' is set, which is able to meet Method B.1 and method C.
> >
> > When 'off' is set, the TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM is not needed
> > to set, so the PKT_TX_UDP_TUNNEL_PKT offload flag is not needed to set,  then
> HW treat  that transmit packet as a non-tunneling packet. It is able to meet
> Method B.2.
> >
> > As to case A, I think it is not mandatory to cover it in csum fwd engine for
> tunneling packet.
> >
> > Is the above description clear for you?
> >
> > > Regards,
> > > Olivier