[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Adding lzma to dpkg's Pre-Depends

On Tue, Jul 29, 2008 at 09:28:01PM +0200, Andreas Barth wrote:
> > On Wed, 2008-04-09 at 06:18:36 +0300, Guillem Jover wrote:
> > > On Wed, 2008-04-02 at 14:01:16 +1000, Anthony Towns wrote:
> > > > On Tue, Apr 01, 2008 at 08:05:06AM +0300, Guillem Jover wrote:
> > > > > As per policy 3.5 I'm bringing this up here. I'd like to add lzma to
> > > > > dpkg's Pre-Depends, so that we can use lzma compressed packages after
> > > > > lenny w/o having to add an lzma Pre-Depends on each .deb package
> > > > > compressed that way.

> > > > Hrm. Alternatively, the packages _do_ pre-depend on lzma though; and
> > > > you're aiming to avoid that by making lzma Essential:yes -- in the same
> > > > way packages that pre-depend on perl or bash don't need an explicit
> > > > dependency.

> > > Well not really Essential, it's going to be pulled like that yes, but
> > > other derivatives, might want to disable it. And I agree with Chris that
> > > it makes sense for dpkg to Pre-Depend on lzma as it's the one calling
> > > it, and that's an internal implementation detail, in case there's a
> > > liblzma in the future and we'd switch to using it, packages should not
> > > require to be changed.

> What advantage would we (as in Debian) have if dpkg pre-depends on lzma,
> instead of the packages pre-depending on lzma?

If dpkg internalizes the lzma support (by static linking, dynamic linking,
or depending on the lzma binary), and packages which use lzma pre-depend on
the correct version of dpkg, then the pre-dependency on dpkg is transitional
and can go away after a release cycle.

If dpkg doesn't internalize the lzma support, then this pre-depends never
goes away (which is ugly), and means additional complexity in calculating
upgrades indefinitely since at any point a user may for the first time be
installing a package that needs lzma.

What is fundamentally different about lzma that it should be handled
differently than gzip and bzip2?

(BTW, from my POV, dpkg Pre-Depends lzma / dpkg Pre-Depends liblzma / dpkg
statically links liblzma are practically equivalent as long as we can assume
that the lzma package itself is maintained in an appropriate manner. 
Whichever one of these options is chosen will pull the new code into base
and have roughly the same effect on the install size.)

> If there isn't an real and strong advantage, I'd rather think it's
> better to not do it.  And, BTW, if dpkg pre-depends on lzma, lzma is
> basically essential.

It's essential for the purposes of calculating the Essential: yes closure,
and not essential in the sense that packages which use its functionality
independently still need to depend on it directly.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek@ubuntu.com                                     vorlon@debian.org

Reply to: