Hi Maemo developers,

This is an important information specially for those handling large
packages. You can find an online version updated at
http://wiki.maemo.org/Documentation/Maemo_5_Developer_Guide/Packaging%2C_Deploying_and_Distributing/Installing_under_opt_and_MyDocs
(or  http://tr.im/yeWM in short)

The N900 has about 100MB of free space in the root file system
partition. This is not very much and would fill up quite quickly when
installing additional applications. As a workaround, the /opt directory
has been linked to a different partition with more space (about 1 GB)
and /home/user/MyDocs is also available in certain cases, with even more
space (about 25 GB). Developers are encouraged to make good use of them,
specially for applications requiring more than 500KB, including
dependencies.

/opt as a good alternative

The /opt directory is on an ext3 partition that is permanently mounted.
Users cannot mess with it by accident. Of course, not everything needs
to be moved to /opt: configuration files are best left in /etc, for
example, and there is no point in moving small files like the various
*.desktop and *.service files.

The maemo-optify tool helps developers to prepare Debian packages that
use /opt. This tool moves selected files inside the package to locations
under /opt, and will symbolically link from the original location to the
new place of the file. An early version of the tool can be found at
http://gitorious.org/maemo-af/maemo-optify - see the README file for
details.
[edit] Considering /home/user/MyDocs

The /home/user/MyDocs directory is another candidate for large
collections of data files included in applications such as game graphics
or maps. Using /opt is mostly transparent to package maintainers and
end-users, but /home/user/MyDocs needs more careful consideration.

The /home/user/MyDocs partition uses VFAT as its filesystem (which has
some limitations compared to ext3) and it is removable: it will be
unmounted and exported over USB when the user plugs in the cable. Also,
/home/user/MyDocs is visible in the File manager. This all means:

    * You need to be aware that VFAT isn't really a POSIX filesystem.
Things like symbolic links, permission bits, etc wont work as nicely as
they do on a real POSIX filesystem.
    * You should be prepared that your files aren't there at all while
the partition is unmounted. You should also not prevent the partition
from being unmounted because you keep some of the files open.
    * User might see your files, could get confused and try to delete or
rename them.

In summary, you can't really put programs, libraries or theme graphics
into /home/user/MyDocs. Instead, use /opt for these.

-- 
Quim Gil
open source advocate
Maemo Devices @ Nokia
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