Building a Debian root filesystem for Banana Pi

The last component of the bootable SD card is the root file system. The location of the root is passed on as a kernel command line parameter. :

CONFIG_CMDLINE="console=ttyS0,115200 root=/dev/mmcblk0p2 rootwait rw"

where ttyS0 is the the initial console, and the second partition of the SD card (mmcblk0p2) is where the Debian root filesystem is. We need a couple of tools available in our development machine :

 sudo apt-get install qemu-arm-static debootstrap binfmt-support  

mount the SD, described in building a bootable SD card for Banana Pi

 sudo mount /dev/sdb2 /mnt  

start the debootstrap process:

 sudo debootstrap --arch=armhf --foreign wheezy /mnt  

Once this process is done, chroot into the filesystem and continue onto the second stage. One key binary is the qemu-arm-static, which emulates an armhf machine within the chroot, to continue the process.

 sudo cp /usr/bin/qemu-arm-static /mnt/usr/bin/  

 sudo chroot /mnt

now continue the debootstrap process in the chrooted environment:

 /debootstrap/debootstrap --second-stage  

when the process is finished, its time to update apt.

 cat >/etc/apt/sources.lst <<EOF  
 deb http://ftp.uk.debian.org/debian stable main contrib non-free  
 deb-src http://ftp.uk.debian.org/debian stable main contrib non-free  
 deb http://ftp.debian.org/debian/ wheezy-updates main contrib non-free  
 deb-src http://ftp.debian.org/debian/ wheezy-updates main contrib non-free  
 deb http://security.debian.org/ wheezy/updates main contrib non-free  
 deb-src http://security.debian.org/ wheezy/updates main contrib non-free  
 EOF  

and then update :

 apt-get update  

configure locales

 apt-get install locales dialog  
 dpkg-reconfigure locales  

setup root password :

 passwd  

setup hostname :

 echo BP-A20> /etc/hostname  

Preapare inittab to spawn a login on console ( /dev/ttyS0 ):

 echo T0:2345:respawn:/sbin/getty -L ttyS0 115200 vt100 >> /etc/inittab  

setup loopback and eth0 interfaces:

 cat > /etc/network/interfaces <<EOF  
 auto lo
 iface lo inet loopback
 
 allow-hotplug eth0  
 iface eth0 inet dhcp  
 EOF  

setup /etc/fstab :

 cat > /etc/fstab <<EOF  
 /dev/mmcblk0p1     /boot     vfat     defaults     1     1  
 /dev/mmcblk0p2     /     ext4     errors=remount-ro 0    1  
 EOF  

install a few useful tools :

 apt-get install openssh-server ntp vim  

exit from chroot, back to the host:

 exit  
 sudo rm /mnt/usr/bin/qemu-arm-static  

now copy the modules, uImage and script.bin

 sudo cp -av /tmp/lib/modules /mnt/lib/  
 sudo sync  
 sudo umount /mnt  
 sudo mount /dev/sdb1 /mnt  

now its time to copy the uImage which was built in this post and script.bin from here.
/mnt should now look like this:

 -rwxr-xr-x 1 root root  50624 Nov 30 08:17 script.bin  
 -rwxr-xr-x 1 root root 3033152 Nov 30 08:18 uImage  

now unmount the SD

 sudo sync  
 sudo umount /mnt  

the SD card is now ready to boot.