[maemo-developers] Backwards compatibility broken PR1.1 SDK

From: Niels Breet niels at maemo.org
Date: Mon Jan 18 23:08:33 EET 2010

I've been discussing this issue with some people before as hypothetical
case, but now it seems that we run into it: Compiling an application
against the PR1.1 SDK creates packages which can not be installed on
earlier firmware releases.

In this case we have have a libosso version which is higher than the
one in previous releases. As this dependency gets automatically added
when compiling in the PR1.1 SDK this poses a problem.

The autobuilder uses the repository.maemo.org repository, so it
automatically uses newer packages when they are available.

For Extras this means that install of an application which is compiled
against the new SDK fails without any description we can expect an
end-user to understand. This is something which should be prevented.

How can we work around this problem:

1: Only compile against the original SDK.
   This prevents new features from ever be available to developers,
   but should work until there is real API/ABI breakage in a new

2: Use version specific repositories
   This needs Application Manager support as we need to fetch from a
   separate repository every time. Also requires us to build against
   every sdk version known to man.

3: Depend on >= mp-fremantle-generic-pr | maemo-version
   We would need a hack in the autobuilder to add depends to pr and
   maemo version. This way a user needs to upgrade to at least the
   required firmware image. I think this will make it easier for an
   end-user to understand what is happening.

   We could, with help of the AM team, even detect in the AM that
   a firmware upgrade is required and give a the end user a nice

Currently the AM doesn't have any means to detect which firmware
version a package requires. Option 3 solve that issue at the same

If you have an alternative solution on how to go about fixing this
issue, then please let me know.

Can we, like with the opt problem, come to a solution with
community power[tm]?

Niels Breet
maemo.org webmaster

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