From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Liuyixian (Eason)" Subject: Re: [PATCH rdma-core 2/2] libhns: Support cq record doorbell Date: Thu, 25 Jan 2018 21:16:58 +0800 Message-ID: References: <9e577314-4fcb-45de-6909-d5b3be570196@huawei.com> <20180118161949.GA18973@ziepe.ca> <20180119200029.GD3437@ziepe.ca> <68e02f2a-0474-bc73-a784-fd52dbbde552@huawei.com> <20180120164625.GA14372@ziepe.ca> <124fa0b2-ac35-a103-205b-252fddea2665@huawei.com> <20180123150421.GA30670@ziepe.ca> <91b5f324-cfaf-e778-2d6c-46000267f2cb@huawei.com> <20180124115141.GG1393@mtr-leonro.local> <20180124163056.GC16845@ziepe.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180124163056.GC16845-uk2M96/98Pc@public.gmane.org> Content-Language: en-US Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe , Leon Romanovsky Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 2018/1/25 0:30, Jason Gunthorpe wrote: > On Wed, Jan 24, 2018 at 01:51:41PM +0200, Leon Romanovsky wrote: >> On Wed, Jan 24, 2018 at 06:35:20PM +0800, Liuyixian (Eason) wrote: >>> >>> >>> On 2018/1/23 23:04, Jason Gunthorpe wrote: >>>> On Tue, Jan 23, 2018 at 08:51:09PM +0800, Liuyixian (Eason) wrote: >>>>> Could you please give me further comments on that email? If you don't >>>>> agree with what I said in that email, can you give some suggestions >>>>> to resolve compatibility issue? >>>> >>>> You can't have a not compatible in your table. >>>> >>>> You need to add some kind of mechanism for userspace to enable the new >>>> features conditionally. >>>> >>>> Jason >>>> >>> Thanks, I will consider your suggestion in next version patch set. >> >> ABI_VERSION cam help you to achieve that. > > ABI_VERSION is mostly totally broken in verbs and breaks > compatability with. It is a last emergency resort. > > Probably in this case you just need to lengthen the response udata > struct and the kernel can detect if the longer struct is provided to > enable the feature and userspace can detect !0 to determine if the > kernel supports it. > > Jason Okay, thanks both of you! I will fix the compatibility problem ASAP. -- 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