[maemo-developers] [maemo-developers] Porting L4-embedded kernel

From: Carl van_Schaik navlrac at hotmail.com
Date: Sat Sep 16 16:23:29 EEST 2006
Hi all,

I just got my 770 and am starting to setup using it as a development board.

My goal is to port the NICTA::L4-embedded kernel to the 770 and run 
virtualized Linux instead of the native kernel.
Firstly I'll need serial console to start development, secondly, I don't 
want to trash the builtin Linux image.

I guess I need to make some sort of adapter to plug onto the serial pins in 
the battery compartment. Is there anything commercial one can buy, or do I 
just make my own with spring contacts?

A quick look around, I noticed /dev/mtdblock2 it where is seems the vmlinux 
image lives, starting at offset 0x800
/dev/mtdblock0 is the nolo 'Nokia Loader' code and /dev/mtdblock1 is the 
config partition?
/dev/mtdblock3 is the initfs?

It would be nice to have a standard bootloader. Unfortunately nokia seem to 
have a propriatary one.
I'm thinking about a couple of options:

1. Port u-boot and flash it into /dev/mtdblock2 in place of Linux. I'll then 
need to place Linux after u-boot. Hope it will fit on the image, otherwise I 
might have to put it on another partition or MMC flash.
At the same time, I'll need to flash the L4 kernel somewhere as well. 
Although initially, serial download could work.

2. Modifiy the initfs such that very early on, before flash is mounted rw, 
have a bootmenu, much like the existing bootmenu program. This could on 
selection of L4, load a kernel module which contains the L4 kernel image, 
and then "take over" Linux and boot the L4 kernel.

Has anyone got experience hacking at the low level on the N770?


Carl van Schaik

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