Re: [PATCH 1/2] libibverbs: Allow 3rd party extensions to verb routines

[Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

>
>> or call an existing function with some new enum value
>
> 5. what happens if we just want to enhance an -- existing -- function 
> - suppose we want to enhance ibv_post_send / ibv_poll_cq to support 
> features like LSO, checksum offload, masked atomic operations, fast 
> memory remote invalidate, etc so we add IBV_WR_NEW_FEATURE / 
> IB_WC_NEW_FEATURE enum values, this step is simple, again if we go the 
> way of the applicayion ensuring through dependencies that they are 
> loaded against libibverbs that supports IB_{WR,WC}_NEW_FEATURE.

Another element to take into account / use here, is the device 
capabilities, in the kernel RDMA stack this is the way to go for 
supporting extended features - those who are not common to all devices, 
e.g the way ipoib queries the device and concludes if checksum/lso 
offloads can be exposed to the network stack, or the rpc/rdma layer 
decides what memory management model to use for rdma conditioned if 
memory extensions etc are supported. But the kernel is one piece, so if 
a cap is defined and there's a driver down there advertizing it, all is 
in place software wise, where in user space, there are some more layers 
to address, as this thread attempts to do.

Or.


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