OLPC Laptop - an open source substandard ?

[Michail Bletsas]

Gabor,

Our main design constraint when we were planning the mesh implementation 
was power consumption.
For a laptop mesh to be dense enough, it is imperative that the user 
doesn't worry about battery consumption when the laptop does nothing else 
but forward traffic for other users.
Existing laptops require something around 10W to forward packets 
wirelessly. Our laptop can do it with  ~3W using the GX2 and a 
conventional laptop WiFi card, however given that we only have a ~25Wh 
battery, that was still to high for our goal.

Thus, we had to utilize an embedded WiFi module with its own CPU and 
memory and Marvell's 88W8388 was pretty much the only choice. To give you 
an idea of the power savings, we can forward frames with less than 400mW 
allowing for our NiMH battery to keep a laptop running as a wireless 
router for 2 days.
802.11s helps keep functional separation between the GX2 and the ARM core 
on the Marvell chip since it operates on layer 2.  So frames are handled 
by the 8388 and packets by the GX2 (we are not running the TCP/IP stack on 
the 8388). This has created some confusion because 802.11s does ad-hoc 
routing using MAC (layer-2) address, however that routing is transparent 
to layer-3.

Marvell already had a full network stack running on the 8388 so they only 
had to add the 802.11s layer to it  (they are paying the people who do 
that development) and that's what they are going to release.
with the intention  for that code to become a module for d80211.


There is a bigger question as to whether it is practical to expect 
complete open source firmware on the 8388 and my take on that is that it 
is, however it will take time that extends well beyond OLPC's deadlines. 

Best,

M.






"Gabor Dolla" <agdolla at gmail.com> 
12/31/2006 11:25 AM

To
"Michail Bletsas" <mbletsas at laptop.org>
cc
devel at laptop.org, gnu at toad.com, jg at laptop.org, "Rob Savoye" 
<rob at welcomehome.org>
Subject
Re: OLPC Laptop - an open source substandard ?






Hi


end of February. In parallel we are working with Marvell to release the 
802.11s source code under GPL.

Who is going to ravel out the 802.11s code from the tangled source ?
I'd help if needed..

What I can not see is how the Linux running on the main CPU and the 
Marvell chip with its own OS  and ip stack work together ? 
Usually the main OS handles the routing, ARP, etc...
If the Marvell chip does the routing what the Linux does ? 

Happy New Year to you, too

Gabor

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