[Mageia-dev] Proposal: Updating released versions (long post)

Frank Griffin ftg at roadrunner.com
Fri Oct 8 21:58:45 CEST 2010

Marc Paré wrote:
> So, as to your proposal, I am in agreement with it. Maybe a suggestion
> (more of a question), seeing as the issues have to deal more with the
> dependencies of a "roll-back", what if, "Backports" would install,
> somehow the software updates in a self compartment kind of way (sorry
> my language terms may not be descriptive enough).

Michael hinted at that, either taking a copy-on-write (brtfs) copy of
the user's system for later restore, or having users install the update
on a VM copy of their system, but the image thing is good for only one
update at a time, and I don't think most users are going to re-install
in a VM to test a new package.  There really isn't a good way to install
in a "sandbox".

> Users know that repositories are activated and some are not at the
> time of install. I think that most users have a faint idea of this.
> But if Backports were to be used more at the user level, what is
> clear, is that, there should be a roll-back feature. If the roll-back
> feature, as a normal course of rolling-back will or could remove other
> softs due to dependencies, then maybe possible option would be to have
> the "Backport" software installations install all dependencies in such
> a way as to isolate them from the larger distro packages. This would
> in effect could make a secondary related-dependency file on the
> system. Then if a roll-back were done a Backported software package
> only the associated dependencies would be deleted.
> Could this be done?

Wherever this can be done, it usually is.  Multiple versions of
libraries can coexist in Linux, so if the new version requires new
libraries, there's no conflict.

The dependencies that cause problems are, for example,  the situation
where you can only have one of a certain service provider and its users
are bound to it by an API which changes between the release version and
the new version you want to install.  For example, if A, B, C, D, E all
use F, and the new version of C has been changed to use the
(incompatible) API of the new version of F, you'd have to install all 6.

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