Hello Axel, On Thu 18 Feb 2021 at 11:01PM +01, Axel Beckert wrote:
> I know this is very obvious, but if you read > > * https://www.debian.org/Bugs/Developer#severities and > * https://release.debian.org/testing/rc_policy.txt > > it seems as if it should be listed somewhere in the policy that package > downgrades MUST not happen during upgrades within the same suite > (i.e. also not during dist-upgrades from e.g. oldstable to stable). > > I searched for "downgrad" (case-insensitively) in the whole policy and > read at least the sections 3.2 "The version of a package" and 5.6.12 > "Version". (If it's documented elsewhere in the policy, it might need a > pointer to there in these sections.) > > Reason for this bug report: > > After reading https://release.debian.org/testing/rc_policy.txt, > especially after word "complete" this paragraph … > > The purpose of this document is to be a correct, complete and > canonical list of issues that merit a "serious" bug under the clause > "a severe violation of Debian policy". > > … I really had a hard time arguing why https://bugs.debian.org/983018 is > actually release-critical, despite I was 100% sure that it is. Luckily > the maintainer did not start discussing but just fixed it. :-) > X-Debugs-Cc'ing the release team for the involvement of rc_policy.txt. Thanks, yes, let's document this in Policy. There would seem to be two things to write down: - .debs are not expected to support downgrades, either in their maintainer scripts or in any other aspects - something about using version numbers correctly so that apt doesn't want to downgrade / doesn't get blocked because a downgrade would seem to be required > The best written source I so far found was > https://wiki.debian.org/SystemDowngrade and hence outside the policy. > > I suggest to add maybe a section 3.2.3 at > https://www.debian.org/doc/debian-policy/ch-binary.html#the-version-of-a-package > with a text like this: > > ---8<--- > 3.2.3 Version numbers of upgrades within one suite > > Version numbers of succeeding package upgrades within the same suite > MUST be strictly greater than the one of the previous package. > > Package downgrades within one suite or when dist-upgrading from an old > stable to a new stable release MUST not happen. > > See 5.6.12.1. Epochs should be used sparingly for cases where you need > to package an upstream release with a lower upstream version > number. Even in that case the package version itself MUST be greater. > --->8--- I don't think this text is clear enough -- Policy is about the contents of packages, but it's phrased in terms of things which will happen -- it refers to upgrades and to downgrades. Could you try writing this in terms of what contents of packages must be avoided in order to avoid the situations you describe? Also, I think the thing about not supporting downgrades should be somewhere too. -- Sean Whitton
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