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Re: [Xen-devel] Question about TCP checksum offload in Xen

On 5 Dec 2013, at 12:47, Paul Durrant wrote:

>>>> On Tue, Dec 03, 2013 at 01:00:23PM +0000, Balraj Singh wrote:
>>>>> It should ideally be for every packet since chksum
>> offload
>>>>> can be turned off and on on the VIF and existing tcp connections should
>>>>> continue.  If not every packet, I need to get a notification or 
>>>>> efficiently
>>>>> detect right away that the setting is changed on the VIF.


> earlier today, i wrote:
>> i think balraj's question arises because the status of checksum offload can
>> change mid-tcp-flow. how does he know whether it's on or off for a given
>> packet?
> Why do you assert that it can change mid-flow? The configuration is decided 
> at ring connect time. Nothing should change after that. If, at that time, the 
> frontend declares it can handle packets with no checksum then clearly it may 
> get some packets that do have checksum as well as ones that don't, depending 
> on where they originated.

i didn't mean to :) i was just trying to point out to ian the reason for 
balraj's question -- i'll leave it to balraj from here...



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