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[85.214.156.166]) by gmr-mx.google.com with ESMTPS id n21si500931lfl.2.2019.03.19.10.33.03 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Mar 2019 10:33:03 -0700 (PDT) Received-SPF: pass (google.com: domain of mosipov@ilbers.de designates 85.214.156.166 as permitted sender) client-ip=85.214.156.166; Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of mosipov@ilbers.de designates 85.214.156.166 as permitted sender) smtp.mailfrom=mosipov@ilbers.de Received: from [192.168.50.164] (d51a48a80.access.telenet.be [81.164.138.128]) (authenticated bits=0) by shymkent.ilbers.de (8.15.2/8.15.2/Debian-8) with ESMTPSA id x2JHX2Er016915 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 19 Mar 2019 18:33:02 +0100 Subject: Re: [PATCH] buildchroot: Allow downgrades when installing packages To: Jan Kiszka , isar-users References: <88c264fd-db0f-55cc-ce5e-f19c11a45320@web.de> <20190225103935.489a466e@md1za8fc.ad001.siemens.net> <65117e48-f372-526a-08e2-35aef444c884@siemens.com> <20190225111530.36c1b655@md1za8fc.ad001.siemens.net> <20190319101001.GK16465@yssyq.m.ilbers.de> <9364cdda-1e01-389a-e586-ff0ea30e028a@siemens.com> From: "Maxim Yu. Osipov" Organization: ilbers GmbH Message-ID: Date: Tue, 19 Mar 2019 18:33:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <9364cdda-1e01-389a-e586-ff0ea30e028a@siemens.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on shymkent.ilbers.de X-TUID: MJHmzU+1XVNu Hi Jan, Tried to apply the patch - CI build failed. See for details: http://isar-build.org:8080/job/isar_mosipov_next/164/console Regards, Maxim. On 3/19/19 11:31 AM, Jan Kiszka wrote: > On 19.03.19 11:10, Baurzhan Ismagulov wrote: >> On Mon, Feb 25, 2019 at 12:08:23PM +0100, Jan Kiszka wrote: >>> Removing -rcX from a version string is lexically a downgrade, >>> logically not. >>> I'm not that sure if you can compensate this. >> >> Debian uses tilde for that, e.g. 1.0~rc1-1+deb9u2. This is addressed in >> https://www.debian.org/doc/debian-policy/ch-controlfields.html#version: >> >>    "First the initial part of each string consisting entirely of >> non-digit >>    characters is determined. These two parts (one of which may be >> empty) are >>    compared lexically. If a difference is found it is returned. The >> lexical >>    comparison is a comparison of ASCII values modified so that all the >> letters >>    sort earlier than all the non-letters and so that a tilde sorts before >>    anything, even the end of a part. For example, the following parts >> are in >>    sorted order from earliest to latest: ~~, ~~a, ~, the empty part, >> a. [7] >> >>    [7] One common use of ~ is for upstream pre-releases. For example, >>        1.0~beta1~svn1245 sorts earlier than 1.0~beta1, which sorts >> earlier than >>        1.0." >> > > Good to know. We will have to educate people coming from OE about this > non-intuitive deviation from how things work over there. > >> >>> Anyway, a real downgrade is a valid development scenario as well for our >>> isar-apt. >> >> Downgrade is supported by the packaging toolchain (dpkg / apt), but >> not by the >> distribution (packages themselves, notably postinst, etc.). >> https://www.debian.org/doc/manuals/debian-reference/ch02.en.html#_emergency_downgrading >> >> says: >> >>    "Downgrading is not officially supported by the Debian by design. >> It should >>    be done only as a part of emergency recovery process. Despite of this >>    situation, it is known to work well in many incidents. For critical >> systems, >>    you should backup all important data on the system after the recovery >>    operation and re-install the new system from the scratch. >> >>    You may be lucky to downgrade from newer archive to older archive >> to recover >>    from broken system upgrade by manipulating candidate version..." >> >> So I'd be reluctant to do that by default. What about extracting the apt >> options into a config file, where the user may add his options? > > I don't see that we should add a redundant, counter-intuitive option. > The user already clearly expressed that packages of choice should be > installed. This is what whole Isar is about: customization. Moreover, > the user will get exactly that by doing a clean rebuild. > > So, please merge. > > Jan > -- Maxim Osipov ilbers GmbH Maria-Merian-Str. 8 85521 Ottobrunn Germany +49 (151) 6517 6917 mosipov@ilbers.de http://ilbers.de/ Commercial register Munich, HRB 214197 General Manager: Baurzhan Ismagulov