ARM/N900/Install/NFS

Contents 1 Requirements 2 Steps for NFS-root 3 NFS-Root with initrd 3.1 Busybox 3.2 Preparing initrd 3.3 Making initrd and booting

Requirements

• Environment for building ARM binaries
• USB networking

Steps for NFS-root

First, you have to get/make a MeeGo rootfs image. You can download a pre-built image (Meego_images_for_N900) or create your own (Creating_ARM_image_using_MIC2). Then you must make the (unpacked) rootfs available in a suitable location on your host system (e.g. /home/nfs/rootfs).

Next, make sure you have NFS server installed on your host and export the rootfs. In Ubuntu:

apt-get install nfs-kernel-server
echo '/home/nfs      192.168.*(rw,no_root_squash,no_subtree_check)' >> /etc/exports
exportfs -v -a

Then, you have to recompile kernel for N900. You must enable (built inside kernel, thus select '*', not 'M'):

* USB Gadget support (Device drivers -> USB Support -> USB Gadget support)
  * USB Gadget drivers (Device drivers -> USB Support -> USB Gadget support -> USB Gadget drivers)
    * Ethernet gadget
  * RNDIS Support (Device drivers -> USB support -> USB Gadget support -> RNDIS support)
* NFS support (File systems -> Network File systems -> NFS client support)
  * NFS-Root support (File systems -> Network File systems -> NFS client support -> Root file system on NFS)
* IP kernel autoconf (Networking support -> Networking options -> IP: kernel level autoconfiguration)
  * all sub-options

Compile and install modules

make
make modules_install INSTALL_MOD_PATH=/home/nfs/rootfs

After compilation is finished you can boot the new kernel with (assuming 192.168.2.14 is your host)

flasher -k arch/arm/boot/zImage -l -b"init=/sbin/preinit ip=192.168.2.15::192.168.2.14 root=/dev/nfs nfsroot=192.168.2.14:/home/nfs/rootfs rootdelay=2 rw console=ttyMTD console=tty0"

You can also hard code the kernel command line options as default when recompiling the kernel (Boot options -> default kernel command string). And further, you can of course flash the new kernel to the device. But still, you have to override the Nolo command line options with flasher

flasher -b

NFS-Root with initrd

OBS: the switch_root step in the script in the end does not seem to work with the latest kernel, you could try it though. Pivot root seems to work.

This method involves using busybox and does not require kernel recompilation. You can more easily keep in sync with the MeeGo kernel.

Busybox

The easiest way to make it working is to build a static binary. Get Busybox sources:

wget http://busybox.net/downloads/busybox-1.16.0.tar.bz2

or

git clone git://git.busybox.net/busybox

Unpack/go to busybox source directory. And edit configuration and compile.

cd  busybox
make defconfig
make menuconfig

# Enable static build (Busybox settings -> Build options -> Buidld BusyBox as a static binary)
make CROSS_COMPILE=arm-linux-
make install CROSS_COMPILE=arm-linux- CONFIG_PREFIX=./initrd

Now you have an initial busybox environment installed in busybox/initrd.

Preparing initrd

To make the initrd bootable and usable you need some preparations. First, make some Initial directories:

cd initrd
mkdir proc
mkdir sys
mkdir dev
mkdir mnt
mkdir -p lib/modules

Some device nodes are needed by the kernel (note, these must be run as root to preserve device node properties):

cp -a /dev/console dev/
cp -a /dev/null dev/
cp -a /dev/ram0 dev
cp -a /dev/tty dev/
cp -a /dev/tty0 dev/
cp -a /dev/zero dev/

Copy kernel modules from your rootfs to the initrd (be sure to use correct kernel version):

cp -r /home/nfs/rootfs/lib/modules/2.6.28-19.1-n900/ lib/modules/

Next, make a script for doing the actual NFS-rooting and :

vim autonfsroot.sh
# edit the script, an example is found below
chmod a+x autonfsroot.sh
rm sbin/init
ln -s ../autonfsroot.sh sbin/init

Here's my autonfsroot.sh

#!/bin/sh
echo "Doing mounts..."
mount -t proc proc /proc
mount -t sysfs sysfs /sys

echo "Loading modules..."
modprobe sunrpc
modprobe auth_rpcgss
modprobe rpcsec_gss_krb5
modprobe nfs
modprobe phonet
modprobe g_nokia

sleep 2

echo "Configuring network interface..."
ifconfig usb0 192.168.2.15

echo "Mounting NFS..."
mount -t nfs -o nolock 192.168.2.14:/home/nfs/rootfs /mnt

echo "Unmounting proc and sys..."
umount /proc
umount /sys

echo "Switching to nfsroot..."
# MLE: switch_root not working for me currently, for some reason
#exec switch_root /mnt /sbin/init
cd /mnt
pivot_root . mnt
exec chroot . /sbin/init

Making initrd and booting

N900 requires cramfs initrd images. This is a bootloader restriction. Go back to the directory containing the initrd dir and then:

cd ..
mkfs.cramfs -b 4096 -n meego_initrd ./initrd/ initrd.img

Now you can load your initrd with flasher and boot to nfs-root:

flasher -n initrd.img -l -b"root=/dev/ram0"

Voilá, you should see MeeGo booting.