[sugar] Bitfrost Activity Isolation being turn ON.

[Michael Stone]

Dear @sugar and @devel,

The sugar, security, and release teams have agreed that the file-system
isolation features provided by Rainbow [1, 2] are close enough to
maturity to be turned on by default in Joyride.

Unfortunately, there will be serious short-term regressions caused by
this change -- for example, activities will not receive any data when
they are resumed until a blocking bug in datastore/Rainbow integration
[#3801] is resolved. 

We are committed to fixing these regressions in a timely fashion.
However, for this to happen, we need your help to find and diagnose
them. Please try to run the software through its paces so that we can
make informed decisions about how much isolation we can actually ship.
Also, please be prepared to update to the latest joyride snapshot on a
frequent basis as we discover and fix the worst regressions.

Finally, in order to help you determine whether bugs that you observe
are being caused by an interaction with isolation, you need to know the
procedure for turning it on and off.

TO TURN OFF ISOLATION:

  From a console, logged in as root:
    
    rm /etc/olpc-security && reboot

TO RE-ENABLE ISOLATION:

  From a console, logged in as root:

    touch /etc/olpc-security && reboot

[It actually suffices to restart X after modifying /etc/olpc-security,
but doing a full reboot will let you start off from a known good state.]

Thanks,

Michael, Marco, Tomeu, Ivan, Kim, Jim, and Walter.

[1]: http://wiki.laptop.org/go/Rainbow            <-- overview page
[2]: http://wiki.laptop.org/go/Taste_the_Rainbow  <-- source code tour