HOWTO Build Arch Linux ARM for A20-OLinuXino-MICRO

Yet another edit in September 2015: As of mid 2015 A20-OLinuXino-MICRO and many other Olimex AllWinner-based board are officailly supported in Arch Linux ARM

http://archlinuxarm.org/platforms/armv7/allwinner/a20-olinuxino-micro

 

Edit: As of late 2014 it is no longer needed to setup toolchain, download and compile kernel, etc… in order to run Arch Linux ARM on your A20-OLinuXino-MICRO board.

ALARM developers provide generic AllWinner sun7i (A20), sun4i (A10) and sun5i (A13, A10s) rootfs and kernel.

There are also u-boot pacman packages for many boards including A20-OLinuXino-MICRO located here:
http://os.archlinuxarm.org/armv7h/alarm/

So here is a simplified version how to install Arch Linux ARM on your A20-OLinuXino-MICRO board:

Follow the official guide for Cubieboard 2 (Installation tab):
http://archlinuxarm.org/platforms/armv7/allwinner/cubieboard-2
Execute steps 1-4.
Download u-boot package for A20-OLinuXino-MICRO, current one is available here:
http://os.archlinuxarm.org/armv7h/alarm/uboot-a20-olinuxino-micro-2014.04-10-armv7h.pkg.tar.xz

Open it with Archive program such as Archive Manager, Ark, etc. Go to boot directory and extract the 3 files (uEnv.txt, script.bin, u-boot-sunxi-wth-spl.bin) on mnt/boot replacing the Cubieboard ones.

Proceed with steps 5-7 from Cubieboard2 guide (except that you need 12V power supply). Once board is up and running and connected to the Internet, install and overwrite u-boot via:

pacman -Sy uboot-a20-olinuxino-micro

End of edit

1. Setup the toolchain

You’ll need a machine running Linux or (the recommended way) – virtual machine running Linux :). For the preparation of this guide I used a VirtualBox VM running the latest stable Lubuntu x86_64 13.04. Make sure that you configure the VM with at least 1 GB memory and 10 GB virtual disk. Assign as many CPU cores as you can to the VM. That will speed up the kernel compilation considerably. It is also recommended to update the VM software packages before you proceed (apt-get update && apt-get upgrade in Debian based distros, yum update in RedHat based, etc…).The commands below are based on my Lubuntu VM setup.

To install the toolchain open a terminal in the VM and write:

$ sudo apt-get install build-essential u-boot-tools uboot-mkimage binutils-arm-linux-gnueabihf gcc-4.7-arm-linux-gnueabihf-base gcc-arm-linux-gnueabihf git wget

2. Building U-Boot

U-Boot (Universal Bootloader) is an open source, primary boot loader used in embedded devices. It is available for a number of different computer architectures, including PPC, ARM, MIPS, AVR32,x86, 68k, Nios, and MicroBlaze (source: wikipedia). U-Boot for AllWinner SoCs is maintained by the linux-sunxi community.

You can download the uboot sources from Linux-sunxi GitHub repository:

$ git clone -b sunxi https://github.com/linux-sunxi/u-boot-sunxi.git

After the download is complete you should have a new directory in your home directory

$ cd u-boot-sunxi/

With the following command you start the build process for A20-OlinuXino U-Boot:

$ make A20-OLinuXino_MICRO CROSS_COMPILE=arm-linux-gnueabihf-

At the end of the compilation you can check if everything is OK by checking file:

$ ls -l u-boot-sunxi-with-spl.bin

Change to the parent (home directory) before you continue to the next step:

$ cd ..

3. Get the board specific FEX file and create script.bin

A FEX file defines various aspects of how the SoC works. It configures the GPIO pins and sets up DRAM, Display, etc parameters. You can find the useful FEX guide here:

http://linux-sunxi.org/Fex_Guide

Download the sunxi-tools:

$ git clone https://github.com/linux-sunxi/sunxi-tools

Change current directory to:

$ cd sunxi-tools/

Download the A20-OLinuXino-MICRO FEX file:

$ wget https://github.com/linux-sunxi/sunxi-boards/raw/master/sys_config/a20/a20-olinuxino_micro.fex

Create script.bin from the downloaded fex file:

$ ./fex2bin a20-olinuxino_micro.fex > script.bin

You can also try the reverse process – generate fex file from script.bin with bin2fex and comapare the 2 fex files (the original one and the one created after2 transformations).

Change to the parent (home directory) before you continue to the next step:

$ cd ..

4. Building Linux kernel for A20-OLinuXino

The current state of the support for AllWinner A20 by the Linux-sunxi community developers is still WIP. However, most of the stuff should work just fine. If you find a bug in the sunxi kernel you can contact the developers via http://linux-sunxi.org/Mailing_list

Kernel sources for A20 are available on GitHub. There are many git branches, but I suppose the most effort is given to sunxi-3.4 tree. You can download the source using the following command:

$ git clone https://github.com/linux-sunxi/linux-sunxi -b sunxi-3.4

After the download is complete go to the kernel directory:

$ cd linux-sunxi/

Now you need A20 kernel configuration file –A20Olinuxino_defconfig. The file contains all kernel module settings. I cannot find an official one so I used the defconfig provided by Dimitar Gamishev (HeHoPMaJIeH):

$ wget https://raw.github.com/hehopmajieh/OLinuXino-A20/master/olinuxinoA20-3.4_defconfig -O arch/arm/configs/A20olinuxino_defconfig

Generate a .config file with:

$ make ARCH=arm A20olinuxino_defconfig

If you would like to disable/enable additional kernel modules you can also execute (Note: you need also “ncurses-dev” package):

$ make ARCH=arm menuconfig

Compile the kernel and modules. This will take from 10 minutes to 2+ hours depending on the speed of your computer and/or the number of processor cores that you assigned to the virtual machine:

$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j4 uImage

$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j4 INSTALL_MOD_PATH=out modules

$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j4 INSTALL_MOD_PATH=out modules_install

At this point you have kernel image and kernel modules.

The uImage file is located in ~/linux-sunxi/arch/arm/boot/

The kernel modules are located in

~/linux-sunxi/out/lib/modules/3.4.xx

where 3.x.xx is kernel version

Don't forget to switch to the parent (home) directory when you are ready with the kernel image and modules compilation:
$ cd ..

5. Build an Arch Linux ARM image (the dirty way)

Download the latest Arch Linux ARM image for sun7i (AllWinner A20) architecture. This image only supports Cubieboard 2 for now, but I hope that A20-OLinuXino will be supported too in the near future.

$ wget http://archlinuxarm.org/os/ArchLinuxARM-sun7i-latest.tar.gz

You can write the rootfs, kernel, u-boot, etc… directly on a microSD card, but I prefer a more flexible way:

• Power down the virtual machine

• Present a new virtual disk with size 900 MB to the VM.

• Start the VM

• Now you have a second drive (/dev/sdb) which you can use as a virtual SD card 🙂

Create partition on /dev/sdb:

$ sudo fdisk /dev/sdb

Press n for new, accept the defaults, write changes to disk with w

Fortmat the partition with ext4 filesystem:

$ sudo mkfs.ext4 -m 1 /dev/sdb1

Create directory in your home directory where you’ll mount the image:

$ mkdir mnt

Mount /dev/sdb1:

$ sudo mount /dev/sdb1 mnt/

Untar the ALARM image:

$ sudo tar -C mnt/ -zxf ArchLinuxARM-sun7i-latest.tar.gz

Change current directory to mnt/boot:

$ cd mnt/boot

Overwrite the files in boot with the files produced in the previous steps:

$ sudo rm uEnv.txt

$ sudo cp ../../sunxi-tools/script.bin .

$ sudo rm u-boot.bin

$ sudo rm sunxi-spl.bin

$ sudo cp ../../u-boot-sunxi/u-boot-sunxi-with-spl.bin .

$ sudo cp ../../linux-sunxi/arch/arm/boot/uImage .

Install the boot loader:

$ sudo dd if=u-boot-sunxi-with-spl.bin of=/dev/sdb bs=1024 seek=8

Switch to ~/mnt/usr/lib/modules and remove the 2 directories:

$ cd ../usr/lib/modules

$ sudo rm -rf 3.3.0-2-ARCH/ extramodules-3.3—sun7i/

Copy the modules that you compiled in step 4 here:

$ sudo cp -aRv ../../../../linux-sunxi/out/lib/modules/* .

Remove the following 2 directories from pacman (Arch package manager) config:

$ sudo rm -rf ~/mnt/var/lib/pacman/local/linux-sun7*

$ sudo rm -rf ~/mnt/var/lib/pacman/local/uboot-cub*

Else on the next update the wrong kernel/uboot will overwrite yours.

Unmount the Arch filesystem:

$ sudo umount mnt/

Create ALARM image:

$ sudo dd if=/dev/sdb of=alarm-a20.img bs=1M

That’s it! Now you have an unofficial ALARM image for your beloved A20-OlinuXino-MICRO 🙂

Default username/password is : root / root

You can find prebuild images in the Olimex forum thread:

 

https://www.olimex.com/forum/index.php?topic=1856.0