Re: [gentoo-dev] FHS compliant KDE install and multi-version support

[Marcus D. Hanwell]

Jan Kundrát wrote:
> Jorge Manuel B. S. Vicetto wrote:
>> Some members of the KDE team have been talking for some time about
>> having a FHS compliant install (define KDE prefix as /usr instead of
>> /usr/kde/<version>).
> What are benefits of such a change? What happens when KDE release a
> version breaking ABI (like "KDE 5")?
We would have the option of using a kde prefix in order to slot it with 
KDE 4, other distros have worked hard to actually slot KDE 3 and 4 
installed in /usr/ this time around. Ideally we would work with them to 
achieve a similar outcome. We would certainly still have options if and 
when this happens, i.e. using an alternate prefix so that they can be 
slotted or truly slotting the two in /usr.
>
> Right now [1], there's a conflict between some non-kdelibs kde3
> libraries (kexiv2, kdcraw) from KDE3 and KDE4, mainly KDE4
> applications being linked with KDE3 libraries. I don't expect ABI
> breakage in 4.x, but what happens after it?
kexiv2 etc are effectively KDE libraries that have recently moved to be 
developed in KDE's repository. We were discussing whether they should 
continue to be bumped in the media-libs category or not. This is a 
recent move and they are certainly not core libs. I haven't checked yet 
but I am not sure whether they break API or not.
>
> Will I be able to use my desktop in the middle of an upgrade from 4.x
> to 4.(x+1), when only half of the packages are already updated?
The KDE apps should just link to the latest kdelibs, KDE guarantees ABI 
stability and so this should be an easy process. It is possible this 
will not always be as smooth as we would like with libkdeedu etc. Can 
Gnome guarantee that everything will continue to work at all stages of 
the upgrade too? I am not sure how I can effectively test that and make 
a promise but from my experience as long as we upgrade the libs first 
and the apps second everything will work well.
>> In case someone is thinking on suggesting it, ignoring FHS or not
>> allowing the install of multiple versions are not valid solutions to
>> this problem.
>
> I might have missed something in your mail, but if you put, say, 4.1
> and 4.2 libraries straight into /usr/lib, are you completely positive
> stuff won't break
So long as things are upgraded libraries first, then applications (as 
specified by the deps) then this should not cause any issues. Although 
we will continue having KDE 4.2 applications depend on >= 4.2.