Use Debian jessie or xenial-proposed as backports in trusty?

[Colin Watson]

On Tue, Apr 05, 2016 at 04:11:57PM +0200, Ralf Mardorf wrote:
> On Tue, 5 Apr 2016 12:38:03 +0100, Colin Watson wrote:
> >libfoo_bar.so.1* would be in a libfoo-bar1 package, while
> >libfoo_bar.so.2* would be in a libfoo-bar2 package, and the two should
> >be coinstallable.
> 
> Ok, the Ubuntu package name scheme is soname related, this makes sense
> and it's easy to understand.
> 
> To what is the package version number related, e.g. what is

The actual SONAME entry in the library's ELF metadata.

  $ objdump -p /usr/lib/x86_64-linux-gnu/libpipeline.so.1.4.1 | grep SONAME
    SONAME               libpipeline.so.1

> 1.4.0 for, if the lib is 2.0.0?
> 
> [root at archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio dpkg -l libvpx2|grep ii
> ii  libvpx2:amd64  1.4.0-4      amd64        VP8 and VP9 video codec (shared library)
> [root at archlinux rocketmouse]# systemd-nspawn -qD /mnt/moonstudio dpkg -L libvpx2|grep so
> /usr/lib/x86_64-linux-gnu/libvpx.so.2.0.0
> /usr/lib/x86_64-linux-gnu/libvpx.so.2
> /usr/lib/x86_64-linux-gnu/libvpx.so.2.0

The "1.4.0" there is the "marketing" version of the library package.
There's no particular technical reason why it should be related to the
SONAME.  This is up to upstream; some set them to be equal, some don't.

For package versions, we use the actual SONAME because that's what
affects binary compatibility, coinstallability, and that kind of thing.

> If it's not related to libs, what is the number behind app names for?
> e.g. "ardour3" for /usr/bin/ardour4?
> 
> http://packages.ubuntu.com/wily/amd64/ardour3/filelist

Who knows?  Could be anything.  Application packages don't normally have
a number attached to them, but sometimes they get one if there's a need
to have more than one version in the archive at once.  I haven't looked
in this case, but I'd conjecture that at one point there was an Ardour 2
that was considered stable and an Ardour 3 that was considered a bit
more bleeding-edge, and then it took a while to get rid of the "3"
suffix.

In xenial, ardour3 is a dummy package that just depends on ardour, so
presumably this has been sorted out by now.

-- 
Colin Watson                                       [cjwatson at ubuntu.com]