This repository provides tools to build Ubuntu Core images for some 'armhf' systems as well as Beagleboard and PandaBoard.
Ubuntu Core is under ongoing development and, as such, these images are meant only to provide a basis for experimentation and a starting point for Snapd + armhf. See Kudos and Caveats.
This package includes any components such as a bootloader that are specific to a particular device (i.e. Overo, DuoVero, Pepper, Beagle, and Panda).
As well as device-specific components, a system vendor could distribute a logo or pre-install other useful packages into any generated images.
1. Grab some required software.
$ sudo apt-get install -y git crossbuild-essential-armhf make snapcraft
2. Build the snap package.
The included Makefile should automate much of this process. Use the -j flag to specify the number of concurrent make processes.
$ make MACHINE=<machine> -j4
After some git-fetching and compiling, fresh binaries built from the newly checked out u-boot repository should be packaged up in a Snappy Gadget package, machine-name.snap. The package build system for Snappy is pretty simple. Have a look at the snap.yaml file in the machine's meta directory and then try building.
$ snapcraft <machine>
If you make changes to any source files, just call make again to rebuild. We can also clean the build... we keep checked-out source around though.
$ make MACHINE=<machine> clean
Individual components can be also be (re-)built and cleaned e.g.
$ make MACHINE=overo uboot
$ make MACHINE=overo clean-uboot
$ make MACHINE=pepper gadget
$ make MACHINE=pepper clean-gadget
We grab the 2016.07 version of the u-boot bootloader from the U-Boot repository and store it in the u-boot directory.
$ git clone git://github.com/u-boot/u-boot.git -b v2016.07 u-boot
We then configure it using the machine-specific defconfig:
| Machine | Machine defconfig |
|---|---|
| overo | omap3_overo_defconfig |
| duovero | duovero_defconfig |
| pepper | pepper_defconfig |
| beagle | omap3_beagle_defconfig |
| panda | omap4_panda_defconfig |
$ cd u-boot
$ make CROSS_COMPILE=arm-linux-gnueabihf- <machine_defconfig>
Build and install the resulting MLO and u-boot.img files.
$ make CROSS_COMPILE=arm-linux-gnueabihf-
$ cp MLO u-boot.img ../<machine>/
Boot built image and save default environment variables.
-
Press any key to stop U-Boot autostart and run:
$ env default -a $ saveenv
Get plain text environment: $ strings uboot.env > uboot.conf.in
Make uenv image: $ mkenvimage -r -s 131072 -o uboot.env uboot.env.in
1. Install latest ubuntu-image snap
$ sudo snap install --channel=edge --devmode ubuntu-image
2. Create a .assertion file similar to this content:
type: model
authority-id: nobody
series: 16
brand-id: nobody
model: <machine>
gadget: <machine>
kernel: linux-armhf
architecture: armhf
timestamp: 2016-08-31T00:00:00.0Z
sign-key-sha3-384: 9tydnLa6MTJ-jaQTFUXEwHl1yRx7ZS4K5cyFDhYDcPzhS7uyEkDxdUjg9g08BtNn
openpgp 2cln
3. Assembly a flashable image.
We'll use the 16.04 release and enable ssh as well developer-mode so we can install unsigned packages. Old Snappy's rollback system is still not supported. Instead of this, a minimal system with only one OS partition will be defined. Image would be equal to 4GB. If card has free space, OS partition will be resized on first boot.
$ UBUNTU_IMAGE_SKIP_COPY_UNVERIFIED_MODEL=1 ubuntu-image <machine>.assertion \
-c edge \
-o panda.img \
--extra-snaps <machine>.snap
3. Burn assembled image.
These image can be directly copied to a 4GB or greater microSD card.
WARNING: This erases anything currently on the microSD card! Note that any mounted partititions of the SD card should be unmounted before writing the image. These steps each take several minutes; your computer isn't hanging, the files are just large.
Format a microSD with the newly created img file. Once the card is created, take a look at the partition structure... there should be two as described above.
# substitute the path to the drive e.g. /dev/sdd or /dev/mmcblk0 (not the
# path of a partition e.g. /dev/sdd1 or /dev/mmcblk0p1) in place of <drive>
# use 'udevadm monitor' when you insert the card to determine the path
$ sudo dd if=<machine>.img bs=4k of=<drive>
$ sync
After the process completes, plug the microSD card into your 'armhf' (or TI) system, boot, login as ubuntu with password ubuntu and start playing with your shiny new Snappy Ubuntu Core!
Technical Aside
There is unpartitioned space at the beginning of the card in which, on some installations, booloader components such as MLO and u-boot.img are written, rather than storing them on the system-boot partition. OMAP4 (DuoVero/Panda) and AM335x (Pepper) use this but, as OMAP3 (Overo/Beagle) u-boot would require a raw boot mode patch, we just place MLO and u-boot.img on the system-boot partition instead.
** 4. Enjoy! **
By way of example, try installing the xkcd-webserver package so you can enjoy random XKCD comics delivered to your browser by your Snappy system:
# on your snappy system
$ sudo snap install xkcd-webserver
On your development machine (on the same network as your snappy device), navigate to http://machine-name.local
In making this repository, there were many useful references. Special thanks to Gumstix guys for their work in previous releases.
A few known issues:
- Standard linux-armhf kernel from Ubuntu Core stucks trying to find the initramfs. You can build your own kernel customizing the Linux Kernel snap for PandaBoard.
- There is a long (~5 minutes) pause before get login prompt as the system makes the new private keys. It is not frozen... just be patient.
The most important:
- There is no validation that all the hardware works. I can only test PandaBoard image, so if you find things that are broken or have suggestions, leave a comment, raise an issue, or best of all, send a pull request!