[ofa-general] Re: [PATCHv4 RFC] Scalable Reliable Connection: API and documentation

[Jack Morgenstein]

On Sunday 12 August 2007 19:49, Michael S. Tsirkin wrote:
> > Why not add xrc_domain to the driver-data area?  Because the xrc_domain is a ib verbs-layer construct.
> 
> It doesn't follow, necessarily.
> Will we be able to void breaking kernel-user ABI if we stick domain
> handle in driver-specific area?

Are you suggesting the following:

1. Do NOT increment the kernel-user ABI
2. Put all src-related changes into the driver-specific area
3. Rely the fact that if userspace is using driver libraries which do not support SRC,
   the src-related functions will not be present, and libibverbs will reject the src-related
   function calls.

   NOTE: This may be the case for SRC function calls.  However, there is no check on qp-type in userspace
   during ibv_create_qp.  Its possible for the user to indicate IBV_QPT_SRC, have it go all the
   way to kernel-space -- and kernel space will take the (garbage) value for the src-domain number.

I think we will find other such holes if we don't increment the kernel-user ABI version.

- Jack