digi:arm-embedded:linux:dey:deycustomrootfs:ros2 [Digi产品中文Wiki]

这是本文档旧的修订版！

DEY是以Yocto的方式开发定制嵌入式Linux系统，这意味着除了添加Meta-Digi外，您也可以添加其它Yocto项目组的layer，包括在生产自动化和物流行业常用ROS机器人操作系统。在github中我们可以看到meta-ros在一直保持开发和演进状态。

Yocto 4.0 Kirkstone (LTS)对应支持ROS2 Humble (LTS)是个长期支持的版本，也是我们要集成的对象。官方文档位于：https://docs.ros.org/en/humble/。更确切地说，在嵌入式Yocto源代码层面安装的文档是： https://github.com/ros/meta-ros/wiki/OpenEmbedded-Build-Instructions

1. 预安装包查缺补漏通常在安装DEY时，应该已经把大部分依赖的安装包都安装好了，但为了防止ROS需要一些额外的包，参考文档，再执行一下它的依赖包安装：

sudo apt update
sudo apt install gawk wget git diffstat unzip gcc-multilib \
        build-essential chrpath socat cpio python3-pip python3-pexpect \
        xz-utils debianutils iputils-ping \
        python3-git python3-jinja2 libegl1-mesa libsdl1.2-dev xterm \
        g++-multilib locales lsb-release python3-distutils time \
        liblz4-tool zstd file
sudo locale-gen en_US.utf8  #这条不一定要执行，因为本来就是用默认英文的

2.找出环境变量和配置文件备用为了整合meta-ros到dey的镜象中，有两种办法，一种是用meta-ros中的镜像名来编译，另一种是参考dey-image-qt来创建dey-image-ros，并在镜像的recipe里加上关键包的支持。为了调查清楚，首先在一个全新的虚拟机上演练一下官方文档安装过程，并检查其配置文件。

mkdir ros2-test
cd ros2-test

mkdir conf
ln -snf ../conf build/.

在build/files/下，有一系列的mcf文件，我们需要拷贝ros2-humble-kirkstone.mcf到配置文件下，可见这是控制编译的主本配置文件，
cp build/files/ros2-humble-kirkstone conf/.

上面这个主要是为了研究配置文件，供以后碰到问题时参考，可以不做这第2步，先直接拉meta-ros到源码，请参考下面

3. DEY的镜像bb文件研读主要的image配置文件在：dey4.0/sources/poky/meta/recipes-core/images和dey4.0/sources/meta-digi/meta-digi-dey/recipes-core/images 其中，core-image-base是在poky的基础镜像文件中添加一些包实现的，所以先研读core-image-base基础镜像，它继承自更基础的core-image(sources/poky/meta/classes/core-image.bbclass) 接下来将拉取meta-ros，并研读相关的bb文件。

4. 拉取meta-ros 下载meta-ros到dey的源码目录下

cd dey4.0/sources
git clone https://github.com/ros/meta-ros.git

我们还需要把这个layer添加到conf/bblayer.conf中，在文件的加上这三句：

  /home/robin/dey-aio/dey4.0/sources/meta-ros/meta-ros-common \
  /home/robin/dey-aio/dey4.0/sources/meta-ros/meta-ros2 \
  /home/robin/dey-aio/dey4.0/sources/meta-ros/meta-ros2-humble \

注意下载下来的目录中，meta-ros-common和meta-ros2-humble是我们需要的。如果要编译ros的镜像，在meta-ros-common中有image相关的recipe，其中： cat ros-image-core可以观察，要定义的东西：

require ${COREBASE}/meta/recipes-core/images/core-image-minimal.bb

SUMMARY = "A small image just capable of starting core ROS."
DESCRIPTION = "${SUMMARY}"

inherit ros_distro_${ROS_DISTRO}
inherit ${ROS_DISTRO_TYPE}_image

IMAGE_INSTALL:append = " \
    ros-core \
"

从上面可以看出，和core-image-base的bbappend类似，这个ros-image-core也是参考poky/meta/recipes-core/images的基础镜像core-image-minimal添加一些包。

core-image-base和core-image-minimal的差别在于：core-image-base使用meta/classes/core-image.bbclass中的IMAGE_INSTALL定义的包，而core-image-minimal则在bb文件里定义来覆盖原来core-image下的包，移除了packagegroup-base-extended，得到一个更小的镜像。所以，ros2的镜像，应该以core-image-base为基础才有意义。

从网络找到的一些参考： https://gitee.com/zxd2021-imx/meta-robot-platform/blob/Hardknott-5.10/imx/meta-robot/recipes-core/images/imx-robot-core.bb

5. 定制core-image-ros 我们给镜像取这个名字，是因为core-image-base能支持cc93的BSP，我们只需加入ros支持即可，这个镜像的bb文件可以放在meta-digi/meta-digi-dey下的recipe-core/images。先一步一步来，从基础的core-image-base中添加ros相关的支持。

首先测试一下没加layer前的效果，也就是bb文件在meta-custom是否能正常编译，将core-image-base.bbappend文件复制出来，重命名为core-image-ros.bb，并加上一句inherit core-image，整个过程如下

cd sources/meta-custom
mkdir -p recipe-core/images
nano core-image-ros.bb

#
# Copyright (C) 2016-2022 Digi International.
#

IMAGE_FEATURES += " \
    dey-network \
    eclipse-debug \
    ssh-server-dropbear \
    ${@bb.utils.contains('DISTRO_FEATURES', 'gstreamer', 'dey-gstreamer', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'alsa', 'dey-audio', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'bluetooth', 'dey-bluetooth', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'wifi', 'dey-wireless', '', d)} \
"

# Remove graphical packages for non-graphical platforms
IMAGE_FEATURES:remove = "${@oe.utils.conditional('IS_HEADLESS', 'true', ' splash ', '', d)}"

CORE_IMAGE_BASE_INSTALL += "dey-examples-digiapix"

# The connectcore demo was removed from 'packagegroup-dey-core' for the
# 6UL (because of rootfs space limits). Add it here, to install it in the
# non-graphical core-image-base.
CORE_IMAGE_BASE_INSTALL:append:ccimx6ul = " connectcore-demo-example"

# SDK features (for toolchains generated from an image with populate_sdk)
SDKIMAGE_FEATURES ?= "dev-pkgs dbg-pkgs staticdev-pkgs"

# Add our dey-image tweaks to the final image (like /etc/build info)
inherit core-image
inherit dey-image

可以成功编译，接下来就是修改这个bb文件，加入ros相关的包。

DESCRIPTION = "A Robot image with base-featured + ROS core Linux system functionality installed."

LICENSE = "MIT"


IMAGE_FEATURES += " \
    dey-network \
    eclipse-debug \
    ssh-server-dropbear \
    ${@bb.utils.contains('DISTRO_FEATURES', 'gstreamer', 'dey-gstreamer', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'alsa', 'dey-audio', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'bluetooth', 'dey-bluetooth', '', d)} \
    ${@bb.utils.contains('MACHINE_FEATURES', 'wifi', 'dey-wireless', '', d)} \
"

# Remove graphical packages for non-graphical platforms
IMAGE_FEATURES:remove = "${@oe.utils.conditional('IS_HEADLESS', 'true', ' splash ', '', d)}"

CORE_IMAGE_BASE_INSTALL += "dey-examples-digiapix"


# SDK features (for toolchains generated from an image with populate_sdk)
SDKIMAGE_FEATURES ?= "dev-pkgs dbg-pkgs staticdev-pkgs"

# Add our dey-image tweaks to the final image (like /etc/build info)

inherit core-image
inherit dey-image
inherit ros_distro_${ROS_DISTRO}
inherit ${ROS_DISTRO_TYPE}_image

IMAGE_INSTALL:append = " \
    ros-core \
"

新建一个项目myrobot，编译首个core-image-ros，并排除错误。

bitbake core-image-ros

首先要排除的是，在ros的三个layer中，对yocto版本限制了，只需把conf/layer.conf中的这句LAYERSERIES_COMPAT_ros-common-layer = “nanbield”中nanbield改为kirkstone，即可。

继续编译，碰到一个错误：

ERROR: ParseError at /home/robin/dey-aio/dey4.0/sources/meta-ros/meta-ros2/recipes-devtools/python/python3-pydantic_2.5.3.bb:10: Could not inherit file classes/python_hatchling.bbclass ，而python3-pydantic_2.5.3.bb

看样子，在meta-digi-dey里放ros镜像的bb是不行的，要大改，试着把这个文件拷到meta-ros-common/recipes-core/images/下，改名为ros-image-dey, 再编译一下看看，

此时，碰到的错误是ParseError at /home/robin/dey-aio/dey4.0/sources/meta-ros/meta-ros-common/recipes-core/images/ros-image-dey.bb:29: Could not inherit file classes/ros_humble.bbclass

看来，应该是不能直接复制双方的recipe，而要有技巧。

根据文档: https://docs.ros.org/en/humble/Tutorials/Beginner-CLI-Tools/Configuring-ROS2-Environment.html ,还是用一个脚本来设置这变量

nano ros-env

ROS_VERSION=2
ROS_PYTHON_VERSION=3
ROS_DISTRO=humble

chmod +x ros-env
source ros-env

再编译仍有错，检索https://github.com/ros/meta-ros/wiki/OpenEmbedded-Build-Instructions#add-meta-ros-to-an-existing-openembedded-project, 里面提到没有用mcf配置文件时的一些方法:

1. 在conf/bblayers.conf 设置ROS_DISTRO，因此在这个文件中加上 ROS_DISTRO = “humble” ，此外也加上ROS_DISTRO_TYPE = “ros”

2. DISTRO ?= “${MCF_DISTRO}” 没用mcf时，用真实的DISTRO替掉这个变量

发现没有把mcf配置文件用起来，一个可能的方案是，把mcf放在 conf/下，另一种情况是合并到conf/local.conf中。

注意到最核心的文档是：https://github.com/ros/meta-ros/wiki/OpenEmbedded-Build-Instructions#add-meta-ros-to-an-existing-openembedded-project ，还有https://github.com/ros/meta-ros/tree/master：文档中的History其中提到：
The initial port of ROS 2 port was undertaken by Erle Robotics. Their work was shared at this repository and integrated upstream into meta-ros.

It has been converted to use recipes generated by superflore. Please see this wiki page for details of what was done and the current development milestones.
wiki地址就是

https://github.com/ros/meta-ros/wiki/Superflore-OE-Recipe-Generation-Scheme

应该是ros转用recipe的方法，

为了得到ros-core, 折衷一下，先把不用的bb注销掉，即python那几个错误的bb，改为.bb-rm，不启用。

精简一下conf/local.conf ，此时可编译通过：

继续除错，主要还是devtool那个目录，应该是版本问题，考虑到不把cc93当成开发电脑，这些python都可以先禁掉

/home/robin/dey-aio/dey4.0/sources/poky/meta/recipes-devtools/python/python3-cryptography_36.0.2.bb

一个可能有用参考：https://community.nxp.com/t5/i-MX-Processors/I-MX8M-plus-AI-Robot-platform/m-p/1303809#M176520

ROS2机器人操作系统的DEY镜像定制