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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6695BC04A95 for ; Wed, 28 Sep 2022 14:58:55 +0000 (UTC) Received: from localhost ([::1]:35040 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1odYWU-00087i-2T for qemu-devel@archiver.kernel.org; Wed, 28 Sep 2022 10:58:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42102) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1odX1k-0007YC-KY for qemu-devel@nongnu.org; Wed, 28 Sep 2022 09:23:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:24790) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1odX1f-0007t3-Ec for qemu-devel@nongnu.org; Wed, 28 Sep 2022 09:23:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1664371378; 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=fgBV04isna9fymBO+7iaFwn1vcnNwSTtAsRHcxWDoSk=; b=JKXQcV/RLxYCuRGsbhpD5XPH1AQuf9iHPENQobeBhh5AfA7MKm/FLxkOgcSv9qbNBbuU49 zZBiUJJcV7vSFhlUKxegnWHpDN2GvWtGzI90oWZrtWL8G4aN4j2rvpTnT01mvbxy4EuK5z XB710sKKoH27l9Ed01bvUErVfs5DOIE= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-201-g9IaoYgxNvyS35IC_eoGXg-1; Wed, 28 Sep 2022 09:22:57 -0400 X-MC-Unique: g9IaoYgxNvyS35IC_eoGXg-1 Received: by mail-wr1-f72.google.com with SMTP id q2-20020adfab02000000b0022cc38d5a8fso1030728wrc.6 for ; Wed, 28 Sep 2022 06:22:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date; bh=fgBV04isna9fymBO+7iaFwn1vcnNwSTtAsRHcxWDoSk=; b=bXd/NEisA41ZvekDtVpGIWBDbIvTzjzUMlJOe65RD92abgt26Hq1TAK7CMC2QW7VxP qdLWvAGVYXgOjPR6gTHMqnGLJFZ7zTWumc7pusgGynma3SNeALsZZFq0IC9ppuhUbTY5 l3wFpUiDvIRtKnmigTfC5doYjpQ4jnn2Idg+CuLkMzaA1WZcaj9lEsu4koegadecASpi eavONJ40bZ1u1Vqk7Yd+YkIr5bpJYbiRlvnulUIxNVSkNX+Vq0F21lFDijNK6zXhIS/p 4FlxYc+3x0CStwpWSOoR/JYu8C4UxKgib4U7GU/59xTKIUQ3JI9Ep5IWQc6mbXSIZhxI w/OA== X-Gm-Message-State: ACrzQf0IOVDdD0LWvR9q1X1Ymtkq1W441e0HaGym8Tl/A6oSsRJTh4Ln 0CO5oClOgUS2gKRKYgDhyAFPHVSwyx2QAF84BVDU7+FTyYRfzud2SgiyZ1AqsQo6EJFEXHn3JYr SS7smE9Aj5Q3KkW4= X-Received: by 2002:a1c:c90c:0:b0:3b4:adc7:9766 with SMTP id f12-20020a1cc90c000000b003b4adc79766mr6976781wmb.66.1664371376073; Wed, 28 Sep 2022 06:22:56 -0700 (PDT) X-Google-Smtp-Source: AMsMyM6mWCgyRwTuLeedAUuarSrDl0JTZxnX7vpf/lJb2zDpiRCbr2v7v/4QPGlNnEQaJL9nDgH2GA== X-Received: by 2002:a1c:c90c:0:b0:3b4:adc7:9766 with SMTP id f12-20020a1cc90c000000b003b4adc79766mr6976747wmb.66.1664371375778; Wed, 28 Sep 2022 06:22:55 -0700 (PDT) Received: from redhat.com ([2.55.47.213]) by smtp.gmail.com with ESMTPSA id k17-20020adfe3d1000000b0022af70874a1sm4854185wrm.36.2022.09.28.06.22.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Sep 2022 06:22:55 -0700 (PDT) Date: Wed, 28 Sep 2022 09:22:50 -0400 From: "Michael S. Tsirkin" To: Warner Losh Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Thomas Huth , Ani Sinha , John Snow , Laurent Vivier , Paolo Bonzini , imammedo@redhat.com, qemu-devel@nongnu.org Subject: Re: Why we should avoid new submodules if possible Message-ID: <20220928091650-mutt-send-email-mst@kernel.org> References: <59150265-44ed-0b14-df1c-42e3f2e97b7e@redhat.com> <20220628060210-mutt-send-email-mst@kernel.org> <20220928052352-mutt-send-email-mst@kernel.org> <20220928054803-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 28, 2022 at 07:15:53AM -0600, Warner Losh wrote: > > > On Wed, Sep 28, 2022 at 7:09 AM Daniel P. Berrangé wrote: > > On Wed, Sep 28, 2022 at 05:53:17AM -0400, Michael S. Tsirkin wrote: > > On Wed, Sep 28, 2022 at 10:37:14AM +0100, Daniel P. Berrangé wrote: > > > On Wed, Sep 28, 2022 at 05:26:42AM -0400, Michael S. Tsirkin wrote: > > > > On Tue, Jun 28, 2022 at 12:21:39PM +0200, Thomas Huth wrote: > > > > > On 28/06/2022 12.03, Michael S. Tsirkin wrote: > > > > > [...] > > > > > > For biosbits if we are going this route then I feel a submodule > is much > > > > > > better.  It records which version exactly each qemu version > wants. > > > > > > > > > > As far as I know, you can also specify the version when using pip, > can't > > > > > you? So that's not really an advantage here. > > > > > > > > > > On the contrary, submodules have a couple of disadvantages that I > really > > > > > dislike: > > > > > > > > > > - submodules do not get updated automatically when doing a "git > checkout", > > > > > we have to update them via a script instead. This causes e.g. > trouble if you > > > > > rsync your source tree to a machine that has no access to the > internet and > > > > > you forgot to update the submodule before the sync > > > > > > > > > > - the content of submodules is not added to the tarballs that get > created on > > > > > the git forges automatically. There were lots of requests from > users in the > > > > > past that tried to download a tarball from github and then wondered > why they > > > > > couldn't compile QEMU. > > > > > > > > > > - we include the submodule content in our release tarballs, so > people get > > > > > the impression that hte submodule content is part of the QEMU > sources. This > > > > > has two disadvantages: > > > > >  * We already got bug reports for the code in the submodule, > > > > >    where people did not understand that they should report that > > > > >    rather to the original project instead (i.e. you ship it - you > > > > >    own it) > > > > >  * People get the impression that QEMU is a huge monster > > > > >    application if they count the number of code lines, run > > > > >    their code scanner tools on the tarball contents, etc. > > > > >    Remember "nemu", for example, where one of the main complaints > > > > >    was that QEMU has too many lines of code? > > > > > > > > > > - If programs includes code via submodules, this gets a higher > > > > >   burder for distro maintainers, since they have to patch each > > > > >   and every package when there is a bug, instead of being able to > > > > >   fix it in one central place. > > > > > > > > > > So in my opinion we should avoid new submodules if there is an > alternative. > > > > > > > > > >  Thomas > > > > > > > > So looking at the latest proposals downloading files from CI, > > > > checksumming them etc etc. No auto checkout, not added automatically > > > > either, right? > > > > > > > > This seems to be the only difference: > > > > - we include the submodule content in our release tarballs > > > > > > That's just one of the issues with submodules. Working with them in > general > > > is not a pleasant experiance. > > > > This is what I asked about at the maintainers summit. > > I'd like to map the issues and see if there's anything > > we can do to solve them. In particular we will likely > > keep using submodules where we historically did > > so it's time well spent. > > > > I agree generally but the big question is what to replace these with. > > Below I assume the replacement is a script such as avocado or pytest > > with its own hashing, calling wget internally etc etc. > > > > > > > Thomas pointed out some of the issues, such > > > as 'git checkout' ignoring submodules, requiring extra steps to sync > them. > > > > > > Not different from a home grown SCM as part of test script, right? > > We're not building a home grown SCM as part of a test script, so > this answer is irrelevant. > > > > There's also the perenial problem that developers frequently send > > > patches that mistakenly include submodule changes, > > > > OK, so the thing to do would be to look for ways to exclude submodule > changes > > from git commits. > > If someone wants to make git suck less with submodules great, but needs > someone to actually do the work. > > > A big part of the problem is knowing which of the following commands I have to > do to undo the uncommitted changes, the committed changes, the staged changes, > etc: > > git submodule update --init --recursive > git submodule update --init > git submodule foreach --recursive git reset --hard > git submodule foreach --recursive git clean -xfd > git submodule foreach --recursive git clean -xfg > > (all of these are in my history, I honestly don't know the difference between > the last two). > And each 'oops' takes time away from upstreaming bsd-user I don't really have > that > much of. I've wasted hours on this over the past year between all the different > ways > it can screw up. > > To be fair, it is a relatively small fraction of the time, but as you can tell > from the > animation in my email it inspires much passion. > > Warner >   OK this is understandable. I think for what we do in qemu (never change upstream really) git submodule update --checkout testsub git update-index --skip-worktree testsub is more or less what most people want. This assumes you have a script that basically does git submodule deinit XYZ git submodule update --init XYZ git update-index --skip-worktree XYZ each time, and do not need to work on the submodule proper. > > > I'd really like to see us doing more to eliminate as much use of > submodules > > > as is possible over time.p > > > > Or try to fix the problems, right? > > Again needs someone to actually make it happen. > > Meanwhile  QEMU already has an integrated test harness in the form > of Avocado that does everything needed. If Avocado had just been > used for this biosbits test in the first place, the test would > likely have already been merged to QEMU, instead of us having this > never ending debate on how to re-invent an alternative to what > already avocado does. > > With regards, > Daniel > -- > |: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange > :| > |: https://libvirt.org         -o-            https://fstop138.berrange.com > :| > |: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange > :| > > >