From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [ewg] Re: [PATCH] rdmaoe/libibverbs: handle binary compatibility Date: Thu, 10 Dec 2009 15:17:55 -0700 Message-ID: <20091210221755.GQ6188@obsidianresearch.com> References: <20091210170536.GA3229@mtls03> <20091210173353.GW1966@obsidianresearch.com> <20091210211455.GA5166@mtls03> <20091210214945.GP6188@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roland Dreier Cc: Eli Cohen , Eli Cohen , Linux RDMA list , ewg List-Id: linux-rdma@vger.kernel.org On Thu, Dec 10, 2009 at 01:57:11PM -0800, Roland Dreier wrote: > Maybe I'm wrong but I don't like setting "don't know" magically to IB > behind the scenes. Well, it isn't just "don't know" it also means "the kernel doesn't support the link_layer query". The kernels that don't support link_layer also only support link_layer == IB for IBV_TRANSPORT_IB. One proves the other.. So IBV_TRANSPORT_IB ports should always return IBV_LINK_LAYER_INFINIBAND unless the kernel supports the new API and says otherwise. You can still have IBV_LINK_LAYER_UNSPECIFIED, but it can't be 0. If this isn't done then again compatability with apps is compromised, what should an app do when it sees IBV_LINK_LAYER_UNSPECIFIED due to an older kernel and newer libibverbs? > And there's no reason why iWARP has to run over ethernet in > principle. Right.. so existing kernels with the new library should return IBV_LINK_LAYER_INFINIBAND for ports on IBV_TRANSPORT_IB devices and IBV_LINK_LAYER_UNSPECIFIED for ports on everything else (IBV_TRANSPORT_IWARP, IBV_TRANSPORT_UNKNOWN) Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html