[PATCH 02/15] Drivers: hv: Add KVP definitions for IP address injection

[KY Srinivasan]

> -----Original Message-----
> From: Olaf Hering [mailto:olaf at aepfle.de]
> Sent: Tuesday, July 17, 2012 12:09 AM
> To: KY Srinivasan
> Cc: gregkh at linuxfoundation.org; linux-kernel at vger.kernel.org;
> devel at linuxdriverproject.org; apw at canonical.com
> Subject: Re: [PATCH 02/15] Drivers: hv: Add KVP definitions for IP address
> injection
> 
> On Sat, Jul 14, K. Y. Srinivasan wrote:
> 
> > diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> > index 68ed7f7..38b561a 100644
> > --- a/include/linux/hyperv.h
> > +++ b/include/linux/hyperv.h
> > @@ -127,6 +127,8 @@ enum hv_kvp_exchg_op {
> >  	KVP_OP_SET,
> >  	KVP_OP_DELETE,
> >  	KVP_OP_ENUMERATE,
> > +	KVP_OP_GET_IP_INFO,
> > +	KVP_OP_SET_IP_INFO,
> >  	KVP_OP_REGISTER,
> >  	KVP_OP_COUNT /* Number of operations, must be last. */
> >  };
> 
> I think this will break the kernel/daemon API for existing binaries.
> Perhaps a forward/backwards compatible API where an older binary
> continues to work with a newer kernel should be added.

You are right. If I were to keep the existing op codes unchanged, I think we can 
maintain backward compatibility - older daemon binaries will be able to function
correctly on newer KVP driver. However, newer daemon binary will require a 
matching KVP driver. Let me first validate what I think is the case. Greg, please drop
the patch-set; I will resubmit the set.

Regards,

K. Y