Network copy-nand

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Introduction

This is a recipe for using copy-nand over the network, so you can replace your OS image without having to copy stuff onto a USB key. I have tested it only with Q2C18 firmware, but it probably works with a few other older versions.

It has some limitations:

1. It doesn't use the .CRC file to check the data (this is because of a deficiency in the firmware HTTP implementation that doesn't let you have two streams open at the same time; that could be worked around at some point by changing copy-nand to pre-read the CRC file into a buffer).

1. It isn't as fast as doing copy-nand from a USB key, but it probably compares favorably to the total process of downloading first to the key, then copying from the key to NAND.

Assumptions

• There is a DHCP server on your network

Procedure

 ok wifi media lab 802.11
 ok patch noop ?open-crcs copy-nand
 ok copy-nand http:\\www.mydomain\images\nand505.img

Discussion

The "wifi" line above sets the SSID of the access point. That line isn't necessary if you are using a wired network interface. The default SSID is "OLPCOFW", so if you are setting up a special wireless network for firmware testing, you can use that SSID name to save some typing.

The "patch" line disables CRC checking, as a workaround for a problem described in the introduction section.

The URL in the copy-nand line must use backslashes instead of forward slashes. Long URLs like the following will also work, if you can manage to type the whole thing without making a mistake.

 http:\\olpc.download.redhat.com\olpc\streams\development\LATEST\devel_jffs2\olpc-redhat-stream-development-devel_jffs2.img

Caveat: The last time I tried using OFW networking in the OLPC offices, DNS name resolution didn't work. I don't know why. But DNS in OFW is working just fine on my home network as I am writing this. If you have trouble with DNS, try using the dotted decimal address (IPv4).

Reflashing the firmware over the network

A similar procedure works for the "flash" command, except that the patch is unnecessary.

 ok wifi media lab 802.11
 ok flash http:\\dev.laptop.org\~wmb\q2c18b.rom

Debugging

If you have trouble with OFW networking, you can often debug the problem by typing "debug-net" before the command that accesses the network. That will dump a lot of information about what OFW is doing and the responses. For example:

 ok debug-net
 ok ping dev.laptop.org
 <lots of output elided - hopefully it is self-explanatory>  

Disclaimer

This is a quick hack procedure provided in the hope that it might be useful, but is not currently supported officially (because I have too many other critical-path issues). If you should choose to file any trac tickets against it, expect to have them reassigned back to you.