This is a method to boot into Debian via fastboot on the nexus one from
your SD-card. This is NOT a chroot Debian image, it is honest to goodness
Debian running directly on the hardware. This is completely non destructive to
the android OS. Connectivity to the device can be provided by adbd, ssh, or
serial console. Wifi works perfectly. I have not tested bluetooth. Touchscreen
works, but needs tweaking. X11 works in framebuffer using the Debian
testing branch (squeeze). In order to get a full fledged X driver with
3D acceleration we'll need the driver from
https://www.codeaurora.org/index.php?xwinp which I haven't been able to get
to build. This doesn't mean it's broken. It just means I suck
at cross compiling.

-Tweak settings to make X more usable.
-Get the CodeAurora MSM/QSD X driver working.
-Find decent method to input text.
-Test bluetooth
-Look into using the GSM radio.
-Figure out how to configure adbd.

This how-to pulls heavily from the debian-arm install guide.

adb (android-sdk)
chroot (on your phone)
sdcard with room for Debian - 2gigs seems to be sufficient for Debian + xfce.
I Had about a gig leftover. For this guide, I'm starting fresh with a 4GB sdcard
that I'm devoting completely to Debian. According to the Debian install guide,
you need at least 32MB of memory and 500MB of hard disk space. The guide
recommends at least 5GB of storage for a comfortable install. But since I'm
using the lighter XFCE4 desktop I haven't had any space issues.

1. Re size the SD card
(don't forget to backup your data before you go messing with partition tables!!)
	(optional) Instead of using a partition on your main SD card, you could
	simply use another sdcard and dedicate the entire thing to Debian.
	Note: android didn't like me very much when I did this. I put in a
	tiny (30MB) vfat partition right at the beginning of the blank sdcard
	I mounted the sdcard on my Ubuntu system and used gparted to break
	off 2 gigs to use for Debian. Make sure you keep the normal android
	sdcard partition as the first partition otherwise android
	will not be able to find it.
	If you're using apps to SD or anything else like that. Debian should
	probably have the last partition. I'm not 100% sure on this since I
	don't use my sdcard for anything else.

2. Format the new partition.
	ext2 is probably best. (least abusive on the sdcard. ext3 & 4 have
	journaling which may be bad for the life of your sdcard)
	I used Gparted for this part as well.

3. If you are installing from an Ubuntu or Debian desktop, install debootstrap
	$ sudo apt-get install debootstrap
	Users of other distros may be able to get debootstrap but I'm not sure.

4. Mount the sdcard on your desktop.
	anywhere will do just remember where you put it :-p
	ex. mount /dev/sde2 /mnt/android

5. debootstrap
	run debootstrap
	you can change to a mirror closer to you if you don't want to use the
	US mirror - http://www.debian.org/misc/README.mirrors
	I'm using the Debian testing release (squeeze). I had issues getting
	X11 running in lenny, and have not tested sid.
	(lenny is stable, squeeze is testing, and sid is unstable)

	debootstrap --arch armel --foreign <release> </path/to/debian> <mirror>
	# debootstrap --arch armel --foreign squeeze /mnt/android \
6. debootstrap(part2)
	Unmount the sdcard from your desktop.
	Reboot the phone here since you've been mucking with the sdcard
	file system. Android didn't like my sdcard until I did.

	$ adb shell

	mount the sdcard somewhere on the android file system.
	look in /dev/block for the sdcard.
	Typically mmcblk0p# where # is the partition number.
	ex. # mount -t ext2 /dev/block/mmcblk0p2 /data/local/mnt


	# chroot /data/local/mnt/ /debootstrap/debootstrap --second-stage
	this will take a while especially if you have a slower sdcard.

6. While that's working, now is a good time to get to work on your kernel
	I used the open source android kernel 2.6.29
	Started with mahimahi_defconfig (default nexus one kernel config from google) and starting customizing from there.
	Things to note.
	- file systems - don't forget to add support for whatever file systems
	  you need. Your root file system support cannot be built as a module.
	- wireless driver config - You may want to change the location the
	  kernel looks for your wifi firmware (this is different from the
	  kernel module).
	  I stuck mine in /etc/firmware, default is /system/etc/firmware.
	  If you don't change this, you will have to put the firmware
	  in /system/etc/firmware
	- wireless - Add in support for standard wifi extensions.
	- networking - standard tcp/ip stuff... iptables if you want ect...
	- I wasn't able to get the kernel to boot into Debian until I turned
	  off initramfs support.
	  (note. this was before I discovered the 'noinitrd' kernel
	  kernel cmdline option. So disabling initrd may not be required)
	- If for some reason you are using ext4, it will fail to mount unless
	  you add in large devices and files support
	- Default kernel command string - has no effect.
	  This gets overwritten when you boot with fastboot or make a boot.img
	- Drivers - I left all the normal android drivers in.
		-Changed the firmware path for wifi.
		-Added in support for virtual terminal under character devices
		-Enabled MSM serial support (if you don't have a serial cable
		 this is useless to you)
		-You can build the wifi driver into the kernel if you want.

	Link to the kernel config I used. Use at your own risk.
	It works for me but I can't promise it's perfect or even good.
	I would love input on building a better kernel config.
If you don't want to build your own kernel. You can download mine here.

7. Chroot and configure Debian.
	There are still some things that need configuring before we reboot into
	Debian. Since fbconsole does not appear to be working, if you don't
	have a serial cable you will be flying blind until Debian is fully
	booted and you can connect with ssh. Since there are still things to do
	before we reboot, we're going to chroot into Debian just like if we are
	using a Debian chroot image.

	For more information and examples of config files.

	It's probably best to use wifi for your data on the phone for this.
	If you're on Linux and connected to the same router as the phone, copy
	over your resolv.conf

	$ adb push /etc/resolv.conf /data/local/etc/resolv.conf

	If you are not in Linux or are not connected to wifi you will need to
	set up resolv.conf with something sane.

	ex. from jay freeman's original Debian chroot.
	$ echo 'nameserver' > /data/local/etc/resolv.conf

	push wifi driver to the device

	$ adb push <kernelroot>/drivers/net/wireless/bcm4329/bcm4329.ko \

	copy /system/etc/firmware/fw_bcm4329.bin to wherever you
	specified in the kernel config.

	# cp /system/etc/firmware/fw_bcm4329.bin /data/local/mnt/etc/firmware/

	Setup environment variables, copy over adbd, and other stuff needed to
	make things work. This should all be run from within an adb shell

	# cp /sbin/adbd /data/local/mnt/sbin/adbd
	# sysctl -w net.ipv4.ip_forward=1
	# export PATH=/usr/bin:/usr/sbin:/bin:$PATH
	# export TERM=linux
	# export HOME=/root

	Next chroot and setup mount points

	# chroot /data/local/mnt /bin/bash
	# mount -t devpts devpts /dev/pts
	# mount -t proc proc /proc
	# mount -t sysfs sysfs /sys

	Welcome to Debian chroot that we all know and love.
	Lets finish configuring this thing.

	Configure adbd to run on boot and create a symlink so
	adbd can find bash.

	Edit /etc/rc.local. Add adbd before exit 0

	#add this to /etc/rc.local
	/sbin/adbd &

	# mkdir -p /system/bin/
	# ln -s /bin/bash /system/bin/sh

	Now we need to be able to install packages
	don't forget if you are not using squeeze to change it here

	# echo 'deb http://ftp.us.debian.org/debian squeeze main' \
	   >> /etc/apt/sources.list
	# apt-get update

	You should see aptitude updating it's package list.

	Install some needed packages

	# apt-get install wpasupplicant wireless-tools udev ssh

	Other packages
	All up to your choice. Things like text editors, X, ect...
	some suggested packages

	# apt-get install locales vi

	Wifi driver
	When you try to load the wifi module, Linux will complain about not
	being able to parse modprobe.d. To fix this run depmod. If it complains
	a directory doesn't exist then create it.

	# depmod -a

	move bcm4329.ko to /lib/modules
	# cp /etc/firmware/bcm4329.ko /lib/modules

	Edit /etc/modules and add the bcm4329 module 

	# /etc/modules: kernel modules to load at boot time.
	# This file contains the names of kernel modules that should be loaded
	# at boot time, one per line. Lines beginning with "#" are ignored.
	# Parameters can be specified after the module name.

	Setup fstab - critical: don't forget to configure the root file system
	or your system won't boot. If you like, mount your vfat sdcard partition
	here too. Don't forget to mkdir for the mount point.
	*note* after boot the memory card is located at /dev/mmcblk0p#.

	Here is my /etc/fstab

	# /etc/fstab: static file system information.
	# file system    mount point   type    options     dump pass

	/dev/block/mmcblk0p2 / ext2 defaults 1 1
	proc /proc proc defaults 0 0
	/dev/mmcblk0p1 /media/sdcard vfat defaults 0 0

	configure network
	These two files will be tuned to what you need.
	Here are a couple examples.


		auto lo
		iface lo inet loopback

		auto eth0
		iface eth0 inet dhcp
		wpa-driver wext
		wpa-conf /etc/wpa_supplicant.conf




	no need for getty so comment it out in /etc/inittab
	if you have a serial cable, configure it here. something like this.
	T0:23:respawn:/sbin/getty -L ttyMSM0 115200 linux

	configure your system's hostname - you can set this to whatever you like
	# echo DebianHostName > /etc/hostname

	Set root password
	# passwd

	Add user account
	# useradd -m yourusername -s /bin/bash
	# passwd yourusername

8. Almost there!
	Double check your configs and have your kernel handy.
	The next step is to boot into Debian.

9. Boot Debian
	put the device into fastboot mode
	$ adb reboot bootloader
	the '-c' flag specifies arguments to pass to the kernel for boot.
	This is probably the bare minimum.

	Format is "fastboot -c 'kernelcmdline' boot zImage"

$ fastboot -c 'root=/dev/mmcblk0p2 rw rootfs=ext2 init=/sbin/init \
rootwait noinitrd' boot zImage
	Wait just a few minutes. DHCP is probably the longest part of this.

10. Connect via ADB.
	If everything went well you should be able to log into the
	phone via adb. adb push and pull work as well. 

	$ adb shell

11. Install X11
	For a basic X11 install. This is probably not what you want.
	# apt-get install xserver-xorg

	You can install whatever window manager/desktop environment you like,
	I used XFCE. Most window managers likely depend on xserver-xorg so it
	will get pulled in when you install. 

	# apt-get install xfce4 

	After I installed xfce4 I was able to get X on the main display by
	simply running startxfce4

	# startxfce4

	By default Debian is configured to only allow root to startx.
	If you want to be able to run X as a user edit /etc/X11/Xwrapper.config
	*note* even with this I haven't been able to run X as a normal user.
	Only root.

	Change allowed_users=console
	to allowed_users=anybody

Currently touchscreen is a little weird. It feels almost like using a
laptop touchpad. The mouse moves much faster then your finger and tapping for
click isn't enabled by default but two finger tap will right click. You can
also move the mouse with the trackball. Clicking the trackball registers a
click. But you have to wiggle the trackball just a tiny bit after you click to
make it register. I am going to work on tweaking the fdi policy files to
make things a little more usable.

Text entry is a bit of a pain point currently. There are several on screen
keyboards out there. One interesting one I found is called cellwriter.
The touchscreen will need to be tweaked before it will work well with
onscreen keyboards.

For other ideas on window managers and other software check out this link
Screenies! http://picasaweb.google.com/JairunCaloth/Debian?feat=directlink

So I’ve been really enjoying my shiny new Nexus One but the stock headphones blow. They fall out of my ears and also don’t offer any noise cancellation which makes them a no-go for work. The headphones have a pretty nifty inline remote that offers skip forwards/backwards and pause/play buttons. I really wanted to take advantage this so I set out to mod my headphones. Now, if you have ever worked with headphone wires then you know how much of a PITA they are. I decided to document the process and post it here so anyone trying to do something similar might learn from some of the pitfalls I encountered and a couple of nifty tricks I discovered. First off I have to thank Alex Whittemore’s blog post which helped me figure out how to prep those tiny evil wires for soldering.

First thing first. Chop off the ear-buds and strip the wire. I used an X-Acto knife for most of the cutting work. For stripping the wire, I rolled it underneath the blade with just a little bit of pressure. Afterwards the insulation pulled right off with my fingers. Once the wire is revealed we see a colored wire, and a copper wire. The colored wire is the for the signal, green is left, red is right and the copper wire is ground.  Make sure you keep track of which is which.
(click thumbnails for full size images)

n1 headphone jacket stripped
Next, I used a Bic lighter to burn off the acrylic insulation from the wires. A few things to note here. First, this stuff catches fire pretty quickly and will burn all the way up to the sheath and melt the sheath if you are not careful. Since we just want to burn the insulation off of the end of the wire let it catch fire and then blow it out quickly. After the initial burn, keep the flame of the lighter on the wire till it glows red hot. At that point, after cleaning it off with some rubbing alcohol it should be ready for soldering. Soldering these wires is a royal PITA. They are flimsy, don’t stay where you put them and getting solder to stick is difficult at best. I found one tip that suggested taking a piece of solid wire, coiling it up like a spring and soldering the headphone wire to it. The solid wire is way easier to solder onto the jack and the coil gives it some springiness so you don’t stress the joints on the jack too much and break them. I took this a small step further and used a pair of pliers to clamp the coil down on the headphone wire after I slid it inside the coil which held it very well while soldering the two wires together.
I know it’s not the prettiest soldering job in the world. But I’m really just a beginner. I trimmed the melted insulation on the solid wire with the xacto knife after this pic was taken.

Next. Heat shrink! This stuff is awesome. Use it to insulate the wires from each other and help protect the joints. I used heat shrink very liberally in the mod. Make sure you leave some way to tell which wire is which. I used different lengths of the solid wire to help me keep them separate.

Final step, soldering on the shiny new headphone jack. I got mine from Fry’s. I’m sure there are 1000 places you can find them online too. Don’t forget to slide any extra heat shrink and the jack sheathe on BEFORE you start soldering it all together. I forgot and had to take it apart and do it again.

I twisted the two ground wires together and added a little solder to help keep them together. Then I soldered the pair onto the ground connector of the jack.

More heat shrink tubing and the finished product! Works like a charm.