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[85.214.156.166]) by gmr-mx.google.com with ESMTPS id f185si101440wme.1.2019.03.19.03.10.03 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Mar 2019 03:10:03 -0700 (PDT) Received-SPF: neutral (google.com: 85.214.156.166 is neither permitted nor denied by best guess record for domain of ibr@radix50.net) client-ip=85.214.156.166; Authentication-Results: gmr-mx.google.com; spf=neutral (google.com: 85.214.156.166 is neither permitted nor denied by best guess record for domain of ibr@radix50.net) smtp.mailfrom=ibr@radix50.net Received: from yssyq.m.ilbers.de (host-80-81-17-52.static.customer.m-online.net [80.81.17.52]) (authenticated bits=0) by shymkent.ilbers.de (8.15.2/8.15.2/Debian-8) with ESMTPSA id x2JAA1Wo015052 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 19 Mar 2019 11:10:02 +0100 Date: Tue, 19 Mar 2019 11:10:01 +0100 From: Baurzhan Ismagulov To: isar-users Subject: Re: [PATCH] buildchroot: Allow downgrades when installing packages Message-ID: <20190319101001.GK16465@yssyq.m.ilbers.de> Mail-Followup-To: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED 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: V5Y/NR2LvHJX 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." > 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? With kind regards, Baurzhan.