Customized images

[Erik Garrison]

On Tue, Jan 06, 2009 at 03:23:32PM -0500, Michael Stone wrote:
> 
> On Mon, Jan 05, 2009 at 02:27:45PM -0500, Carlos Dario Isaza Zamudio wrote:
> >I have a fully customized XO and i need to take an image from it to be
> >installed on several computers inside the project. The thing is i need it to
> >be separated from the activity pack, like the ones you use to update via
> >USB.
> 
> Hi Carlos,
> 
> Thanks for the great questions.
> 
> >Questions
> >1) When i take the image from this one and install it into another, will i
> >have two computers wchi are exactly the same?
> 
> No. Each XO contains unique "manufacturing data", stored in a
> non-volatile memory which is separate from the main (1GB) non-volatile
> memory.
> 
> Moreover, when you boot an XO, it runs some software which "dirties" the
> filesystem. You'd want to "clean" the filesystem by undoing some of
> these edits before you clone the image onto lots of other machines.

Dirty might be too general a word.  Specifically there are a number of
changes made to system files during the first boot of the machine
which you might not want to copy between machines.  (SSH keys, for
instance, are generated once at first boot on every XO.  Also,
hardware-dependent information from the firmware is cached on the NAND
after first boot.)

We haven't worked on figuring out what pieces of the system are touched,
so, as Michael notes, copying the machines can have unintended side
effects.  It seems that nearly everyone who tries to distribute images
by cloning runs into some oddities.  That said, it also seems that this
method of customization is the most appealing and straightforward.  It
has come up several times recently and I think the time has come to
properly evaluate it.

Erik