Bug#586424: dmsetup has circular Depends on libdevmapper1.02.1

Pierre Ynard linkfanel at yahoo.fr
Sat Feb 4 13:53:49 UTC 2017


> > I don't understand this. Merely having a libary installed should
> > not imply any userspace actions. If some packages need device
> > mapper functionality, they need to depend on dmsetup, not just
> > libdevmapper.
> 
> Yes, it does. The sole purpose of libdevmapper is to configure the
> device mapper part of the kernel. To do this it needs a working udev.

I run LVM on a non-dynamic system without udev installed. The udev rules
are a no-op on my system. libdevmapper still does its job just fine. So
it seems that no, it doesn't "need" a working udev.

If it "needed" a working udev to apply the dmsetup udev rules, then it
should have a dependency not just on the udev rules, but on udev itself.
But we've gone over that issue already before:

> lvm2 (2.02.64-1) unstable; urgency=low
> 
>   * Enable udev sync, remove explicit udev dependency, bump dmsetup
>     dependency to get it working. (closes: #543163)
> 
>  -- Bastian Blank <waldi at debian.org>  Wed, 19 May 2010 13:33:09 +0000

So, from this point of view, it doesn't make sense to say that
libdevmapper needs a hard dependency relationship with something that
may or may not be a no-op, depending on the status of other packages
that have however no dependency with it.

Beyond the circular dependency, there is the problem of respecting the
policy and avoiding package and daemon bloat through unwarranted hard
dependencies. All I want and need on my system is the LVM init service,
the LVM utilities, and the device mapper dynamic libraries they use;
which is main and significant functionality in itself. However with the
current lvm2 package I have no choice but getting way more than that.

Do you think it could be beneficial to create a meta-package, under
whose umbrella the dependencies on anything needed for a "fully working
LVM experience" could be simply moved? Between plugins and udev, there
seem to be different degrees of what a dependency is, so that could be a
nice approach to it.

Best regards,

-- 
Pierre Ynard
"Une âme dans un corps, c'est comme un dessin sur une feuille de papier."



More information about the pkg-lvm-maintainers mailing list