Re: [PATCH 2.6.37] RDMA/cxgb3: When a user QP is marked in error, also mark the CQs in error.

[Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

On 10/20/2010 04:54 PM, Roland Dreier wrote:
>   >  - bump the ABI since the create_cq uverbs response changes.
>
>   >  - detect older libraries and reduce the mmap size accordingly.
>
> If you bump the ABI, will older libraries still run with the new driver?
> Or will they just bail out with "unsupported ABI version"?
>
>    

Well, the existing lib versions don't look at the ABI at all. :)  So 
we're ok.   And I put logic in the driver to detect the old libs vs ABI 
1 libs.

> If you can work with both old and new userspace libraries, is there any
> reason for an ABI break anyway?
>    

The ABI version bump tells the new library that the kernel driver 
supports this new functionality.  I don't know another way to do this 
without the ABI bump.  The kernel driver detects the library ABI via the 
size of the create_cq response that's passed in from the lib.  But in 
the other direction, I think the only was is with the ABI number.

Steve.

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