From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 119F1C433E0 for ; Wed, 5 Aug 2020 02:42:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D847C2086A for ; Wed, 5 Aug 2020 02:42:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XSi9fIxX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726571AbgHECma (ORCPT ); Tue, 4 Aug 2020 22:42:30 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:54172 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725864AbgHECma (ORCPT ); Tue, 4 Aug 2020 22:42:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596595348; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=j55K/Dwi4G9px2pH7AKtokjX8kCpdSz/LKIcvwedD1k=; b=XSi9fIxXvZCkFrN++slkD8EOFMAAo1js/uI3rDrANfEeKzXr5jQMaWEW51/NBwcV5zZNKv 4SWWHj7Btg9llQh33Athon/HgoNY6ETN/gQ/8JQT2c+numquYX1SE2uRpfON+ke8jy9Eca nE4q9YQgaVOmrlD2xyIuF3iSQi4et+o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-497-0uvxif-TMCaNGmd8p_0tTQ-1; Tue, 04 Aug 2020 22:42:25 -0400 X-MC-Unique: 0uvxif-TMCaNGmd8p_0tTQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 97D3A101C8A0; Wed, 5 Aug 2020 02:42:22 +0000 (UTC) Received: from [10.72.13.71] (ovpn-13-71.pek2.redhat.com [10.72.13.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id 285AA28559; Wed, 5 Aug 2020 02:41:55 +0000 (UTC) Subject: Re: device compatibility interface for live migration with assigned devices To: Yan Zhao Cc: Cornelia Huck , Alex Williamson , kvm@vger.kernel.org, libvir-list@redhat.com, qemu-devel@nongnu.org, kwankhede@nvidia.com, eauger@redhat.com, xin-ran.wang@intel.com, corbet@lwn.net, openstack-discuss@lists.openstack.org, shaohe.feng@intel.com, kevin.tian@intel.com, eskultet@redhat.com, jian-feng.ding@intel.com, dgilbert@redhat.com, zhenyuw@linux.intel.com, hejie.xu@intel.com, bao.yumeng@zte.com.cn, smooney@redhat.com, intel-gvt-dev@lists.freedesktop.org, berrange@redhat.com, dinechin@redhat.com, devel@ovirt.org, Jiri Pirko , Parav Pandit References: <20200713232957.GD5955@joy-OptiPlex-7040> <9bfa8700-91f5-ebb4-3977-6321f0487a63@redhat.com> <20200716083230.GA25316@joy-OptiPlex-7040> <20200717101258.65555978@x1.home> <20200721005113.GA10502@joy-OptiPlex-7040> <20200727072440.GA28676@joy-OptiPlex-7040> <20200727162321.7097070e@x1.home> <20200729080503.GB28676@joy-OptiPlex-7040> <20200804183503.39f56516.cohuck@redhat.com> <20200805021654.GB30485@joy-OptiPlex-7040> From: Jason Wang Message-ID: <2624b12f-3788-7e2b-2cb7-93534960bcb7@redhat.com> Date: Wed, 5 Aug 2020 10:41:54 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200805021654.GB30485@joy-OptiPlex-7040> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2020/8/5 上午10:16, Yan Zhao wrote: > On Wed, Aug 05, 2020 at 10:22:15AM +0800, Jason Wang wrote: >> On 2020/8/5 上午12:35, Cornelia Huck wrote: >>> [sorry about not chiming in earlier] >>> >>> On Wed, 29 Jul 2020 16:05:03 +0800 >>> Yan Zhao wrote: >>> >>>> On Mon, Jul 27, 2020 at 04:23:21PM -0600, Alex Williamson wrote: >>> (...) >>> >>>>> Based on the feedback we've received, the previously proposed interface >>>>> is not viable. I think there's agreement that the user needs to be >>>>> able to parse and interpret the version information. Using json seems >>>>> viable, but I don't know if it's the best option. Is there any >>>>> precedent of markup strings returned via sysfs we could follow? >>> I don't think encoding complex information in a sysfs file is a viable >>> approach. Quoting Documentation/filesystems/sysfs.rst: >>> >>> "Attributes should be ASCII text files, preferably with only one value >>> per file. It is noted that it may not be efficient to contain only one >>> value per file, so it is socially acceptable to express an array of >>> values of the same type. >>> Mixing types, expressing multiple lines of data, and doing fancy >>> formatting of data is heavily frowned upon." >>> >>> Even though this is an older file, I think these restrictions still >>> apply. >> >> +1, that's another reason why devlink(netlink) is better. >> > hi Jason, > do you have any materials or sample code about devlink, so we can have a good > study of it? > I found some kernel docs about it but my preliminary study didn't show me the > advantage of devlink. CC Jiri and Parav for a better answer for this. My understanding is that the following advantages are obvious (as I replied in another thread): - existing users (NIC, crypto, SCSI, ib), mature and stable - much better error reporting (ext_ack other than string or errno) - namespace aware - do not couple with kobject Thanks > > Thanks > Yan >