OpenEmbedded / Yocto Project evaluation BSP layer for TQ-Systems ARM SOM

This README file contains information on the content of the meta-dumpling layer.

Please see the corresponding sections below for details.

[[TOC]]

Overview

Abstract

This layer provides recipes to generate images to help evaluation of TQ-Systems CPU modules and Starterkits. This layer additionally contains optional fixes and extensions for other layers as far as is needed / useful for TQ-Systems SOM and some initial example distro support.

Dependencies

This layer in the checked out branch depends on:

URI: https://git.yoctoproject.org/poky
branch: hardknott
layers: meta

URI: https://github.com/openembedded/meta-openembedded.git branch: hardknott
layers: meta-oe

URI: https://github.com/tq-systems/meta-tq.git
branch: hardknott
layers: meta-tq

When using one of the distros definded in this layer you need additionally the meta-poky layer from the poky repo that defines poky and poky-tiny which the distros defined in this layer depend on. Note Recipes and bbappends in this layer do not depend on meta-poky

URI: https://git.yoctoproject.org/poky
branch: hardknott
layers: meta-poky

This layer additionally contains optional fixes and extensions for other layers as far as needed for TQ-Systems SOM. Most of these bbappends are implemented under dynamic-layers and are only visible, if the original layer is in your bblayer.conf. For details look for BBFILES_DYNAMIC in Yocto Project documentation.

Coding style

It is recommended to use the Format_Guidelines from openembedded.

Patches

Please submit patches against the meta-dumpling layer to the maintainer:

Maintainer: Markus Niebel [email protected]

Additionally you can use github's collaboration features.

Usage

Adding the meta-dumpling layer to your build

Run 'bitbake-layers add-layer /meta-dumpling'

Assuming the tq layer exists in subdir sources at the top-level of your yocto build tree, you can add it to the build system by adding the location of the tq layer to bblayers.conf, along with any other layers needed. e.g.:

BSPDIR := "${@os.path.abspath(os.path.dirname(d.getVar('FILE', True)) + '/../..')}"

BBLAYERS ?= "\
...
    ${BSPDIR}/sources/poky/meta \
    ${BSPDIR}/sources/poky/meta-poky \
    ${BSPDIR}/sources/poky/meta-openembedded/meta-oe \
    ${BSPDIR}/sources/meta-tq \
    ...
"

Image recipes

The meta-dumpling layer defines images recipes for test / evaluation of TQ-Systems SOM:

image	intended use
tq-image-small	based on poky core-image-minimal, usable for UBI rootfs
tq-image-small-debug	based on poky tq-image-small, added debug features
tq-image-generic	based on poky core-image-minimal
tq-image-generic-debug	based on tq-image-generic, added debug features and packages
tq-image-generic-rt	based on poky core-image-minimal, PREEMPT_RT kernel
tq-image-generic-rt-debug	based on tq-image-generic-rt, added debug features and packages
tq-image-weston	based on poky core-image-weston
tq-image-weston-debug	based on tq-image-weston, added debug features and packages
tq-image-qt5	based on tq-image-weston, added qt5 support
tq-image-qt5-debug	based on tq-image-qt5, added debug features and packages

Attention: These image recipes can be used as a starting point for own customization. Every recipe comes in two flavours. The images suffixed with debug add debug-tweaks to the IMAGE_FEATURES to have an open root login for console and ssh for ease of development and testing. The non suffixed images simply define a base feature set for the use case and contain a lot of test utils, to evaluate and test TQ-Systems starterkits. Because of the intended use case, these image recipes are intended as a starting point for development but should not be used directly for production images. Depending on the actual project, security must be taken in account.

Note: Out of the box (without debug-tweaks in IMAGE_FEATURES) the images without -debug suffix do not allow user login. This should be default for the vast majority of embedded systems. If one need an user that can login, see poky documentation for extrausers.bbclass and following example:

# add user <username> with password <passwd> and force password change at first login
IMAGE_CLASSES += "extrausers"
USERADDEXTENSION = "useradd-staticids"
USERADD_UID_TABLES = "files/passwd"
USERADD_GID_TABLES = "files/group"

EXTRA_USERS_PARAMS = "\
    useradd <username> ; \
    usermod -P <passwd> <username>; \
    passwd-expire <username>; \
"

Example distros

The meta-dumpling layer defines distros as starting point for own customization. These distros are also available for usage together with vendor based kernel / vendor hardware support layer.

distro name	purpose
spaetzle	small size for usage with [Q]SPI-NOR flash
spaetzle-nxp	small size for usage with [Q]SPI-NOR flash with NXP / FSLC kernel
spaetzle-ti	small size for usage with [Q]SPI-NOR flash with TI kernel
dumpling	systemd, features depends on machine settings
dumpling-nxp	systemd, features depends on machine settings with NXP / FSLC kernel
dumpling-ti	systemd, features depends on machine settings with TI kernel
dumpling-wayland	like dumpling, additional wayland / weston
dumpling-wayland-nxp	like dumpling-nxp, additional wayland / weston
dumpling-wayland-ti	like dumpling-ti, additional wayland / weston

Attention: These distro configs can be used as a starting point for own customization. Because of the intended usage, they are focused on demonstration. These configs should not go into a production usage without thorough review. Depending on the actual project, security must be taken in account.

SDK usage

For each of the distros an SDK can be built. The SDK contains everything needed for cross application development for the target hardware. To build the SDK along with the image, run

bitbake <image> -c populate_sdk

After building the SDK, an installation script can be found in ${TMPDIR}/deploy/sdk. Simply run the script to install the SDK on your development host. The script will provide you with a default install path, but it can be customized when needed. Depending on your installation path you will possibly need root access to install the SDK.

Developing in SDK environment

Source the bash script located inside your chosen installation path, starting with environment-setup followed by some architecture specifications. For example:

source <path/to/sdk/installation>/environment-setup-cortexa53-crypto-tq-linux

Inside the SDK environment you can now develop your application using the cross compiler tools. To verify the environment run env or display the value of CC:

echo ${CC}

Direct usage of SDK cross toolchain

You can also invoke the cross compile tools directly. They are located in the SDK installation path in the sysroots folder. In this folder you will find two more folders. One sysroot for your target hardware, containing cross compiled libraries and headers among others and one sysroot for your development host architecture (typically x86_64). This second sysroot contains the cross compile tools in <path/to/sdk/installation>/sysroots/<host_architecture>/usr/bin/<target_architecture>.

Known issues

• tq-image-small:
  • DHCP is not working
  • restricted support for hardware
  • some warnings from init scripts