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Date: Fri, 7 Dec 2012 11:52:43 -0800 (PST)
From: Joseph Gasparakis <joseph.gasparakis@intel.com>
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To: David Miller <davem@davemloft.net>
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Subject: Re: [PATCH v3 1/4] net: Add support for hardware-offloaded
 encapsulation
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On Fri, 7 Dec 2012, David Miller wrote:

> From: Joseph Gasparakis <joseph.gasparakis@intel.com>
> Date: Fri, 7 Dec 2012 11:41:46 -0800 (PST)
> 
> > 
> > 
> > On Fri, 7 Dec 2012, David Miller wrote:
> > 
> >> From: Joseph Gasparakis <joseph.gasparakis@intel.com>
> >> Date: Fri, 7 Dec 2012 10:24:17 -0800 (PST)
> >> 
> >> > So the idea here is that the driver will use the headers for checksumming 
> >> > if the skb->encapsulation bit is on. The bit should be set in the protocol 
> >> > driver.
> >> > 
> >> > To answer the second comment, the flags that we use in this series of 
> >> > patches is NETIF_F_IP_CSUM, NETIF_F_IPV6_CSUM and NETIF_F_SG. These are 
> >> > the bits that we propose will be used for checksumming of encapsulation. 
> >> > As per a previous comment in v2, the hw_enc_features field should be used 
> >> > also in the future when NICs have more encap offloads, so one could
> >> > indicate these features there from the driver.
> >> > 
> >> > Furthermore, I submitted a patch for Rx checksumming, where NETIF_F_RXCSUM 
> >> > is used, again in conjunction with skb->encapsulation flag. As I mention 
> >> > in my logs, the driver is expected to set the ip_summed to UNNECESSARY and 
> >> > turn the skb->encapsulation on, to indicate that the inner headers are 
> >> > already HW checksummed.
> >> > 
> >> 
> >> This is the kind of language that belongs in the commit message and
> >> code comments.
> >> 
> > Sure. I'll wait to gather some more feedback if there is any and I will 
> > re-spin this off adding more code comments and clarify this in the logs.
> 
> Great.
> 
> Please note that this request applies to your receive side change too.
> 
I believe the logs are sufficient in the rx patch:

This patch adds capability in vxlan to identify received
checksummed inner packets and signal them to the upper layers of
the stack. The driver needs to set the skb->encapsulation bit
and also set the skb->ip_summed to CHECKSUM_UNNECESSARY.

...but I can add more comments to the code if this is what you are 
referring to.