Does in olpcrd ever do anything?

Martin Langhoff martin.langhoff at
Mon May 4 12:17:50 EDT 2009

Today I've been working through the olpcrd and the OATC code, new
keyjector, etc. Quite interesting read.

One of the interesting things is: our "init" is, which
checks for existing activation, registers signal handlers to deal with
zombies, and then ... and sleeps. The sleep is heralded by a "do OATC
stuff" comment.

As far as I can see, it hasn't setup any other signal handler, it's
not listening to any kernel event (inotify, etc). It is truly
sleeping. Is there anything I am missing?

Frankly, I don't think we gain much from having a "smart" init past
the init phase. The flow I am envisioning is as follows:

 - Let sleep, or let it exec a real lightweight init
(assuming it releases memory).

 - Take advantage of the NetworkManager event called on ifup. When we
associate successfully to a network, if we haven't gotten a lease
recently, and the network looks like it may have a XS, request one.

 - If we get a new lease, validate it and save it as
/security/lease.sig . We have the option here of being paranoid about
DoS via OATC and writing it out to /security/new-lease.sig , to be
re-validated and formally installed in the next boot. I don't think
it's worthwhile.

 - If we get a STOLEN, shut down immediately.

What do we miss, if we compare this with an 'OATC-checking init' model?

 - If you have root, it's easy to remove the NM script, whereas
fiddling with init is pretty hard. However, even if you remove the NM
hooks, the checks are performed on boot.

 - If the lease runs out while the machine is running, the next check
is at reboot time.

In any case, the XO has been rendered quite useless as it'll only run
until it's rebooted...

Why do I want to add logic in the NM hooks and not in the pythonesque
init? A simple lightweight init is a good thing, and simple scripts
from NM are easily made failsafe -- getting init to listen to NM
events, establish network connections, etc is a fairly treacherous


 martin.langhoff at
 martin at -- School Server Architect
 - ask interesting questions
 - don't get distracted with shiny stuff  - working code first

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