[OLPC-devel] OLPC "bootloader"

[Ray.Tseng at quantatw.com]

>From manufacture point of view:
1. Re-install from USB Flash Drive: it's hard to control the image distributed on many many USB flash drive  
2. Re-install from Wireless: Lot of wireless communication may interfere, and throughput will slow down.

Do we consider the option#3?
3. Re-install from USB Wired LAN
Stable, high speed and central control.

Ray Tseng 6/23/06

-----Original Message-----
From: devel-bounces at laptop.org [mailto:devel-bounces at laptop.org] On Behalf Of Christopher Blizzard
Sent: Monday, June 19, 2006 9:49 PM
To: Jordan Crouse
Cc: devel at laptop.org
Subject: Re: [OLPC-devel] OLPC "bootloader"

Jordan Crouse wrote:
> Is this still what you are thinking about using to bootstrap from 
> LinuxBIOS to the kernel on the NAND flash?  Now that LB seems to be 
> fairly sane, and we've moved to the 1MB ROM, I think its time to start 
> pulling everything together.

Agreed on this point.  I've challenged Marcelo and David to get to the point where we're "telling the whole story" on the re-install.  This means going from the BIOS to a boot image to a re-install onto the NAND flash and actually running our software off the internal flash.

We haven't seen working LinuxBIOS down at the office yet so the idea was to use an external flash drive to boot a kernel that gets up and running enough to load and boot a kernel off the NAND flash using kexec.

> 
> One thing I noticed is that we need a good way to write a new image to 
> the NAND flash.  I'm sure this has probably been discussed in other 
> e-mail threads or on IRC, but as far as I know, there really isn't a 
> consensus on how we want to do this.
> 
> I think the initrd is as good a place to do it as any - we could pull 
> a new .jffs2 image from a USB key or the network (or, heaven help us,
> zmodem) and write it to the MTD block.  The code isn't at all 
> complicated, its just a matter of agreeing on how things will be done.

We've spent some time talking about the experience, but not so much about the mechanisms.  We've been focused on a couple of areas:

1. Re-install from USB Flash Drive

This could take the form of a .jffs2 image or we could blast a filesystem from the USB flash onto a pre-formatted .jffs2.  The IBM thing that's listed after this message on this thread gives us more options.  I'm glad that's public now.

2. Re-install from Wireless

This is the one that needs the most work and thought, and one of the main reasons why we went to 1MB. :)  My thought was to build a very simple client on the target machine and then build a reasonably complex server on a host machine that "takes over" the machine and manages the entire install experience.  The idea being that it's easy to make a small client that doesn't change often, but the server is something that will change over time.  Plus you're always going to re-install with someone you know sitting next to you, both for security and bandwidth reasons.

As for the underlying technology for the wireless, I imagine something similar to the USB flash drive experience, once you pull down a second stage image.  It's getting that image that makes things a little challenging.

--Chris
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