libdm + dmctl import

[haad <haad%netbsd.org@localhost>]

Hi Folks,

I would like to import new library for device-mapper manipulation.
It's called libdm [1].  As you probably know device-mapper is a
kernel driver which is used in our LVM.
With libdm we can work with dm driver without gpl2 tools. With [2]
there will be 2 users of libdm in base

* libdevmapper will be converted to use libdm for dm communication
* dmctl device-mapper administration utility
* I plan to write dm driver rump atf tests with dmctl

dmctl program was written as replacement for gpl2 licensed dmsetup.
It has same functionality than dmsetup and uses only libdm library.

In [1] there are 2 manual pages one for dmctl.8 and other one for
libdm.3 they need some grama and mdoc fixes.

With libdm and dmctl in base we can use dm driver for many interesting
things which do not need to be related to LVM.

* zoltan is working on deduplication target for dm
* I have some patches which are replacing ccd driver with dm while user
   can still used ccdconfig and other utilities.

Plus we can add dmctl to /rescue because it uses only BSD licensed
code + we can remove one gpl2 licensed tool, dmsetup.

I would like to import libdm and dmctl to base this weekend.
Do you have any suggestions, comments ?

[1] http://www.netbsd.org/~haad/libdm_dmctl.diff
[2] http://www.netbsd.org/~haad/libdm_libdevmapper-18112010.diff
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Regards.

Adam