A small ramdisk system running modern Debian to support mesh networking on ARM single-board computers
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README.md

A small ramdisk system running modern Debian

Build Status

This project will create system images for installing a Debian-based router.

There are several supported target boards - for a quick list, look at the subdirectories in the boards directory. Note that with the standard ramdisk confg used (using "tmpfs"), the images will not work with boards that have less than 512Meg of RAM.

In the future, it will create a fully working mesh node, with cjdns and IPFS software installed.

Documentation Index

There documentory README files in most directories with explanations as to what that directory is used for. These files are located where they are so as to stay close to the code and config that they are documenting. Be sure to read this main README and all the other ones to get a full view of the project. There are also some diagrams showing some of the build process in the docs directory.

TOP-GS07 RT5572 WiFi adapter Note

During the testing of this adaptor, it was found to get very hot. If insufficient cooling is provided, this adaptor could overheat and fail to work properly. In a subtropical summer environment, it was found that this would occur within a couple of minutes of use. Removing the plastic cover allows some cooling and was enough to complete at least half an hour of successful light testing.

Building the image

Multiple board targets are supported, but they all use the same basic process. The following commands will build for the Orange Pi Zero:

make build-depends

make -C boards/sun8i-h2-plus-orangepi-zero image

First, any packages required to complete the build are installed - this needs to be done for both the Debian environment and the specific board environment, which is why there are two lines.

The last command builds the image. Once the disk image is completed, it will placed in the output dir.

Starting a clean build

Most of the files in this repository have dependancy tracking, so that changing one of them will rebuild just the appropriate parts. Due to the interaction with downloading external packages and building entire Debian root dirs, those dependancies do not cover all possible changes.

Therefore, it is sometimes important to "clean" the repository to force a full build to be done. Note though that it should always be considered a bug when a missing dependancy is found.

You should never need to completely delete your repository and do a new clone from upstream!

There are two different targets provided to clean out the repository:

make clean
make reallyclean

If both are to be run, they should be done in that order, or just combined into one command:

make clean reallyclean

The "clean" target trys to remove the minimum set of files to produce a clean rebuild. It trys not to delete any large downloads, thus speeding up the following build. It also takes care to use sudo to remove some files that will have been created with different owners.

The "reallyclean" target just nukes everything from each build dir.

Using the image

Once the image is built, and you have the disk image file from above, write to the raw sdcard with a command line tool like dd or a graphical tool like Etcher.

For dd:

lsblk -d -o NAME,SIZE,LABEL
echo "Verify and run: sudo dd if=output/$IMAGE of=$DISK"

Warning: Don't overwrite the wrong disk!

Booting and using the system

A wireless access point will be automatically started on all detected wifi adaptors - including those hot-plugged after bootup. Any internet connection plugged into the ethernet port will be shared out over the access point.

Note: There is currently a bug with stopping/restarting the hostapd, so if you unplug an adaptor, it will not automatically work again until a reboot is done.

During testing the following default settings are used:

  • wifi ssid: test2
  • wifi passphrase: bbbbbbbb
  • user: root
  • pass: root

An ssh server is started on bootup, so the simplest way to login is to connect to the wifi and use the root password.

During development and debugging, it is very helpful to use a serial console to see the boot messages and login. It may also be useful to read the section below on running this image in an emulator.

Note: uncompressing the (currently approximately 120Meg uncompressed) initrd will take a noticeable amount of time. The network will not be setup until that has been done, so nothing will happen for a while. For some reason, this also applies to the kernel messages.

Tests on one orange pi zero show that the time from power on until a login prompt on the serial console is about 1 minute.

Applying persistent configurations

Mesh communities may wish to customize nodes by distributing configuration files to specify local network information and hardware settings. The system image supports loading of these persistent configuration files at runtime. Please refer to the Runtime Configuration section in hamishcoleman/debian-minimal-builder for details.

Test the Debian image using Qemu

It is possible to boot the Debian system up in an emulator. This is useful during development to speed up testing, but is also useful for exploring the system and learning its features before committing to the purchase of any hardware.

Testing with the armhf architecture

The armhf architecture is an environment that is closer to the real-life Single Board Computers that are expected to be used - and it uses exactly the same binaries that would be used on those. However, it is usually a slower emulator.

make build-depends

make -C boards/qemu_armhf test

Once the build has completed, it will boot up inside the emulator. The console of the emulator is connected to your terminal window.

To exit the emulator, use Ctrl-A then x.

Testing with the i386 architecture

While this is not the expected architecture for most physical hardware, it is a much faster emulation. Additionally, all the debian packages, configuration and customisation is the same as the armhf architecture.

make build-depends

make -C boards/qemu_i386 test

The i386 test also creates a 2G persistent storage that shows up as /dev/vda. To use this virtual disk, create and format a partition, any data written to that partition will persist across systemctl reboot.

fdisk /dev/vda        # Follow instructions to create a partition
mkfs.vfat /dev/vda1   # Format the created partition as vfat
mount /dev/vda1 /mnt  # Mount the formatted partition onto /mnt

To exit the emulator, use Ctrl-A then x.

Debian ramdisk builder

The debian directory contains the Debian builder - see the README in that dir for more details.