Re: pending changes for TOE support

David Christensen wrote:
>>>> + * The TOE API assumes that the tcp offload engine can offload the
>>>> + * the entire connection from set up to teardown, with 
>> some provision
>>>> + * being made to allowing the software stack to handle 
>> time wait. If
>>>> + * the device does not meet these criteria, it is the 
>> driver's responsibility
>>>> + * to overload the functions that it needs to in 
>> tcp_usrreqs and make
>>>> + * its own calls to tcp_output if it needs to do so.
>>>>
>>>> While I'm familiar with TCP, I'm less familiar with the 
>> scope of what cards
>>>> support for TOE.  Do we know of any cards that are less 
>> capable than the
>>>> chelsio card in this respect, or are they all sort of 
>> on-par on that front?
>>>> I.e., do we think the above eventuality is likely?
>>> I don't have any way of knowing. I think it is probably safe to say
>>> that any vendors that don't meet that criteria now will in 
>> the future
>>> as transistor density increases.
>> There are cards (or at least I've heard talk of this) that do partial
>> TCP offload - that is the connection setup and teardown are handled by
>> the operating system and that only data transfer is offloaded.  I'm in
>> the wrong country to chase down details on this ;(
> 
> You are referring to Microsoft Chimney architecture which would be
> supported by all TOE adapters that operate under Windows (our 
> NetXtreme II controllers included).  There are IP issues related to
> a chimney style implementation that would likely preclude their use
> under FreeBSD including passing TCP state information between the
> host OS and the controller among them.

No, I'm not referring to anything Microsoft.  They aren't the
only operating system vendor that's working in this space.

It would be preferable if FreeBSD could just see what the raw
hardware is capable of and decide for itself what kind of
architecture makes sense.

Darren