How to Run Headless Linux on Amlogic S905 Devices Such as MINI MX or K1 Plus

A few week ago, I had been informed that Amlogic S905 U-boot and Linux source code was released, and one person use the code and other resources to load a minimal Ubuntu 14.04 image to his K1 Plus TV box and released the installation instructions and the image (Thanks olin!). I also have K1 Plus here, but since I’ve just finished reviewing Beelink MINI MX, I decided to use the latter instead. The instructions below boot Linux from the (micro) SD card, and can still boot Android if you remove the SD card.

Modifying U-boot environment

The instructions include opening the box, and connecting or soldering a USB to TTL debug board to access U-boot and change some parameters. But later once an image with network is working, you could also build and load fw_setenv and fw_saveenv, and do the same steps with an Android shell and without the need to open the device.

Click to Enlarge
Serial connection to MINI MX (Click to Enlarge)

K1 Plus has the UART headers populated so you don’t have to solder anything, but MINI MX requires a little bit a soldering on the clearly marked Tx, Rx, GND pins.

Connect your USB to TTL debug board to your computer, configure minicom / putty / screen to 115200 8N1, start the board, and press the space bar to interrupt the boot:


You may want to run printenv in order to back the default settings:


Now you can change some settings in U-boot in order to allow for Linux to boot from SD card. If you are doing so directly in Android terminal via adb, you can replace setenv and saveenv by fw_setenv and fw_saveenv (no present in MINI MX firmware):

Flash Ubuntu image to the SD card

First download the Ubuntu image: ubuntu-14.04-headless-arm64.7z.

I’ve done this step in an Ubuntu computer, but you could also perform the same steps in Windows with 7pzip and Win32DiskImager. Install required tools and uncompress the image.


Insert the micro SD card (2GB or greater) in your computer, check the device with lsblk, and flash the image to your SD card by replacing /dev/sdX in the command below by your actual device.

Get the Device Tree File for Your device

If you are trying this on K1 Plus, you can skip that step, but if you are using another device, in my case Beelink MINI MX replacing the device tree file in /boot/dtb.img might be a good idea. For example, MINI MX would only get a Fast Ethernet connection with K1 Plus device tree file, but once I extracted the one from the Android firmware I got an Gigabit Ethernet connection.

If you’ll need to get boot.img either from some firmware update file, or directly from the NAND flash. I don’t have firmwre for MINI NX, so I dumped the boot partition with an adb shell:


Then I followed the instructions to extract a device tree file from Android, until I get boot.img-second.gz file, which I copied to the boot partition in the SD card with Ubuntu

Run Ubuntu in MINI MX

You may want to extend the rootfs partition in the SD card with gparted, or you’ll only have a small part of your SD card used. Now insert the SD into your Amlogic S905 TV box, and connect the power.

After some time getting wasted waiting for the network, you should be able to access to command line by logging in with user debian and password temppwd:


That’s a minimal image so there’s plenty of free space and memory:


All four cores are shown when I check the cpuinfo:


The kernel is build with Android’s option “CONFIG_ANDROID_PARANOID_NETWORK“, so all network configuration must be done with root:


So there’s some work to be done, but at least that’s a start.

[Update: It’s easy to put the case together with the serial wires by cutting the plastic case a little.

Beelink_MINI_MX_with_UART_cables]

 

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