Hi Oscar,

> Item 2 in the documentation reads: "if the selected disk has several
> partitions, on which partition should DoudouLinux data be recorded?"
> To me, it means that if I want to dedicate a separate partition to
> persistent data, then we must create the partition before persistence
> activation.

Yes, but this persistence mode is not provided by our tool. If you
really want to store your persistence data onto a partition directly
(not kind of archive file), then you have to create your partition, give
it the correct label (see below) and format it using a Linux filesystem
preferably (ext3 for example).

> 1) Which parameter must we specify for this partition? I mean type
> (ext3 I guess), max size, mount-point, name (name is a big doubt as
> explained below).

The persistence tool embedded in DoudouLinux will search for a partition
of a given name at boot. If found, it will automatically mount the
partition as the persistence partition, provided you used a writable
filesystem type. The exact name can be retrieved using the following
command from the console:

$ cat /proc/cmdline

Alternatively these parameters are also written in our Live build
configuration scripts:

http://svn.gna.org/viewcvs/doudoulinux/live/trunk/config-base/binary?view=markup

Beware that there are lots of parameters among those is the persistence
name. I think the technical reason evoked in our documentation for not
providing partition persistence is that some partition types (guess
which one ;) ) do not accept very long names, 8 letters for instance.
However it should not be more than 12 or 16 letters on Linux
filesystems.

There is no limit on partition size (except ext3 limitations) and you
don't need to specify a mount point since it is not mounted as a
standard partition. Instead it uses a process called “aufs” that mixes
into one several filesystems that provide files/directories trees that
may overlap. In this process, the standard DoudouLinux filesystem is
mounted read only while the persistence filesystem is mounted read/write
and may replace files from the DoudouLinux filesystem.

> 2) May we create this partition after Doudoulinux is installed?
> I guess the answer is yes because Doudoulinux installer re formats the
> whole disk... but better ask to be sure... 

Yes, I've ever found myself doing such things while debugging our
installer!

> A foot note in the document reads:  "[2] The only exception is the
> DoudouLinux installer which activates persistence using directories
> because it changes some settings in the system."  To me, since our
> Doudoulinux boots from hard disk, then we are forced to use the
> directory mode for data persistence.

If you installed it “manually”, yes. Our installer changes the boot
parameter that defines the partition name, to fit the maximum number of
letters. This name doesn't defaults to a short name on the CD because I
thought our persistence file should have a name easy to understand to
avoid people delete it by mistake! We have design constraints from
Debian Live and partition specifications that avoid us to make it short
and understandable enough.

> Another paragraph in the document reads: "In the case of persistence
> stored into directories, the disk partition containing these
> directories has a special name. As for single file storing, when
> DoudouLinux starts in persistence mode and finds such a partition
> name, the partition gets “mounted”. The technical limit that
> DoudouLinux has with this method is the reduced length of this name,
> which is incompatible with the persistence file name of the former
> case."  

It's the another version of my former explanations!

> 3) Who gives that "special name" to the partition, we or the
> activation tool? If we, where can we take that special name from?

The installer tool does while the persistence tool cannot set a
partition for persistence. The installer tool names it live-rw which
requires to remove the boot parameter “persistent-subtext=doudoulinux”.
If you really want to do it by yourself, you'll have to edit the boot
parameters that should lay somewhere in /live/ in a file named
“live.cfg”.

> 4) If we want to add additional software (like Open Office), then we
> must select mode 4 (user and system). When and where can we tell the
> tool which mode to use? In the supplied screen shots there is no place
> to specify that.

Persistence tool → only modes 1 and 2 are available
Installer tool → uses mode 4 silently

> 5) What are the implication of the limitation in the length of the
> partition name? I guess it must be important since is referenced in
> the document... but there is no more info about that.

The live boot process builds the persistence partition/file name by
concatenating “live-rw” and the persistence subtext. In our case, the
full name should be “live-rw-doudoulinux”, really too long for a
partition label but clear enough for a single file on an USB key
containing many other data.
 
> 6) Since the PC is to be shared by three kids, is there a way for each
> kid to have his/her won creations saved so the other users can not
> destroy them? I mean a sort of  user log in and repository per user?
> Initially I thought in a USB key per kid, but some user and system
> data must continue to be shared to all users...

No, DoudouLinux is currently designed as a child toy: switch on and
play, no authentication, no password. But this does not mean this is
impossible! DoudouLinux is a standard Debian system, you can then create
as many users as you want and just need to copy the files from the
matching “fake” DoudouLinux user. Currently the trick is the following:

* the main activities menu is a GDM login screen
* main activities are separate Linux users (fake users) with settings
that make their environment different
* only the DoudouLinux fake users are shown on the login screen
* passwords are all disabled on the system (this is restricted to the
fake DoudouLinux users in our development version)

Adding new users is possible but requires that you choose one main
activity only for each one and that you change the GDM login screen
configuration to show their face.

We have in mind to remove these fake users in the future and implement
our main menu in a standard application. This would ease the
customization you'd like to do but also would make more complicated to
manage the various environments.

NB: I also have 3 kids and have already seen them angry because another
one had modified their work! Of course they only use DoudouLinux at
home.

-- 
Cheers,
JM.

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