DragonBoard 820c Getting Started With Linux

This page has instructions to get started with Debian or OpenEmbedded on the DragonBoard 820c board.

Bootloaders

Throughout these instructions, we are assuming that you have been able to flash the board with an initial build from Qualcomm such that you can boot the board into fastboot. If you cannot get the board to boot into fastboot, then you need to get in touch with the person that provided you with the board.

Onboard storage

The onboard storage is partionned such as :

• /dev/sda9 is userdata and is ~24GB
• /dev/sde18 is system and is ~3GB
• /dev/sde17 is boot

For now there is no rescue tool which is provided, so it is not recommended to change the partition layout. The root file system can be installed in userdata or system based on how much space is needed. It is even possible to install a Debian image in userdata and an OpenEmbedded image in system partition.

Installing Debian

The DB820c is supported starting with build #8 from : http://snapshots.linaro.org/debian/pre-built/snapdragon-tracking-arm64/. Build #8 is based on 4.6 kernel, and has minimal features set (mostly console, UFS, 4 core running at the lowest speed). Features will be added in this builds stream. While build #8 is based on 4.6 kernel, next builds will switch to 4.7 and so on, until we reach the next LTS kernel version.

To install the Debian root file system:

1. Download either the developer or the alip image from the link above
2. Uncompress the root file system image
3. Flash the image into userdata (or system).

So, assuming you are using build #8:

wget http://snapshots.linaro.org/debian/pre-built/snapdragon-tracking-arm64/8/linaro-jessie-developer-qcom-snapdragon-arm64-20160706-8.img.gz
gunzip linaro-jessie-developer-qcom-snapdragon-arm64-20160706-8.img.gz
fastboot flash userdata linaro-jessie-developer-qcom-snapdragon-arm64-20160706-8.img

You can download the prebuilt boot image as well, from the same location. However note that the boot image is by default going to try to mount the file system on rootfs partition, like on DragonBoard 410c, so you need to update the boot image before flashing it, since we do not (yet) use the rootfs partition on DB820c:

wget http://snapshots.linaro.org/debian/pre-built/snapdragon-tracking-arm64/8/boot-linaro-jessie-qcom-snapdragon-arm64-20160706-8.img.gz
gunzip boot-linaro-jessie-qcom-snapdragon-arm64-20160706-8.img.gz
abootimg -u boot-linaro-jessie-qcom-snapdragon-arm64-20160706-8.img -c "cmdline=root=/dev/disk/by-partlabel/userdata rw rootwait console=tty0 console=ttyMSM0,115200n8"

You might need to replace userdata with system, of course.

Installing an Open Embedded based image

Initial support for DragonBoard 820c has been added into the OpenEmbedded QCOM BSP later, including the appropriate kernel recipe. To build an image for Dragonboard 820c , simply follow the same instructions as usual, from Dragonboard-410c-OpenEmbedded-and-Yocto. When you select the MACHINE to build for, pick dragonboard-820c.

The board is being added to the Linaro Reference Platform OpenEmbedded builds, and prebuilt images for this board should appear in the coming days here : http://builds.96boards.org/snapshots/reference-platform/openembedded/.

Kernel source code

The Linux kernel used for DragonBoard 820c can be found in the Linaro Qualcomm Landing Team git repository. For now the support for this board is preliminary and can only be found in the integration-linux-qcomlt branch, which is regularly rebased on recent mainline.

git: http://git.linaro.org/landing-teams/working/qualcomm/kernel.git
branch: integration-linux-qcomlt
defconfig: arch/arm64/defconfig kernel/configs/distro.config

To build the Linux kernel, you can use the following instructions:

git clone -n http://git.linaro.org/landing-teams/working/qualcomm/kernel.git
cd kernel
git checkout -b kernel-16.06 debian-qcom-dragonboard410c-16.06
export ARCH=arm64
export CROSS_COMPILE=<path to your GCC cross compiler>/aarch64-linux-gnu-
make defconfig distro.config
make -j4 Image dtbs KERNELRELEASE=`make kernelversion`-linaro-lt-qcom

Additionally, you might want or need to compile the kernel modules:

make -j4 modules KERNELRELEASE=`make kernelversion`-linaro-lt-qcom

To boot the kernel image, you will need a fastboot compatible boot image, and you can refer to this wiki for instructions to create such an image.