438 lines
16 KiB
Markdown
438 lines
16 KiB
Markdown
<img align="center" src="./images/rpi/RPi-Logo-Landscape-Reg-PRINT.png" width="30%">
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<sub><sup>Image taken from [Raspberry Pi website](https://www.raspberrypi.org/trademark-rules/).
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Raspberry Pi is a trademark of the Raspberry Pi Foundation</sup></sub>
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# Getting started on the Raspberry Pi
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The FSFW can be run on a Raspberry Pi with the Linux OSAL, using
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an ARM linux (cross) compiler. Instructions will be provided on how
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to do this.
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## General Information
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The following instructions will show how to build the example on the Raspberry Pi directly.
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It will also show how to cross-compile on a host machine and mirror the Raspberry Pi sysroot folder
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on the host machine so that the same libraries and headers used on the RPi are used
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for the cross-compilation process.
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Some Eclipse project files were provided as well to help with setting up the indexer in Eclipse
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more quickly.
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## Prerequisites for direct compilation and cross-compiling
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1. SSH connection to the Raspberry Pi working
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2. Raspberry Pi linux environment set up properly
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3. `CMake` installed
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## Setting up general prerequisites for Linux systems
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1. Install `CMake` and `rsync`
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```sh
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sudo apt-get install cmake rsync
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```
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2. Configure the Raspberry Pi Linux environment. The last section of the
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[Linux README](README-linux.md#top) specifies how to set up a UNIX environment for the FSFW and
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is also applicable to the Raspberry Pi. SSH into the Raspberry Pi and
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follow the instructions in that section.
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3. Install the `gpiod` library
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```sh
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sudo apt-get install gpiod libgpiod-dev
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```
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## Getting started on the Raspberry Pi
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Make sure to follow the steps above. Now you should be able to build the software on
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the Raspberry Pi. A ssh connection to the Raspberry Pi is assumed here
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You can build the software with the following commands
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```sh
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mkdir build-Debug-RPi
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cd build-Debug-RPi
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cmake -DOS_FSFW=linux -DTGT_BSP=arm/raspberrypi -DLINUX_CROSS_COMPILE=OFF -DCMAKE_BUILD_TYPE=Debug ..
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cmake --build . -j
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```
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## Prerequisites for cross-compiling
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These prerequisites are valid for Linux as well as Windows hosts.
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1. ARM Linux cross compiler installed
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2. Raspberry Pi sysroot folder mirrored on the host machine, using `rsync`
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3. gdb-multiarch installed on host for remote debugging or `tcf-agent` running on Raspberry Pi
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## Cross-Compiling on a Linux Host
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Steps tested for Ubuntu 20.04. Adapt accordingly for used Linux distribution.
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The following steps are based on this
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[stackoverflow post](https://stackoverflow.com/questions/19162072/how-to-install-the-raspberry-pi-cross-compiler-on-my-linux-host-machine).
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For the steps show here, we are also going to assume that a new Raspbian image
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based on Debian buster is used. If this is not the case, it is recommended to
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follow the steps in the stackoverflow post above and to make sure that the
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toolchain binaries are added to the path accordingly.
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### Setting up prerequisites for cross-compiling
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1. Install the pre-built ARM cross-compile with the following command
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```sh
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wget https://github.com/Pro/raspi-toolchain/releases/latest/download/raspi-toolchain.tar.gz
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```
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Then extract to the opt folder:
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```sh
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sudo tar xfz raspi-toolchain.tar.gz --strip-components=1 -C /opt
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```
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Please note that this version of the toolchain might become obsolete in the future.
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If another toolchain installation is used, it is still recommended to unpack the toolchain in the
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`/opt/cross-pi-gcc` folder so that the Eclipse configuration and helper
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scripts work without adaptions. Add the folder to the system path. On Linux,
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this can generally be done with the following command
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```sh
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export PATH=$PATH:"/opt/cross-pi-gcc/bin"
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```
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You can add this line to the `.bashrc` or `.profile` file in the `$HOME` directory
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to add environmental variables permanently. More experienced users can
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perform this step is a shell script which is `source`d to keep the environment clean.
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Test the toolchain with the following command
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```sh
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arm-linux-gnueabihf-gcc --version
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```
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2. Set up a sysroot folder on the local host machine. Make sure the SSH connection to
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the Raspberry Pi is working without issues. Then perform the following steps
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```sh
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cd ~
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mkdir raspberrypi
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cd raspberrypi
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mkdir rootfs
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cd rootfs
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pwd
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```
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The result of the `pwd` command will be used later to sync the root file
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system of the Raspberry Pi to the host machine.
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With a Raspberry Pi 4, you can replace `<ip-address>` with `raspberrypi.local` and
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when using the default rootfs path, you can replace `<rootfs-path>` with
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`$HOME/raspberrypi/rootfs`.
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```sh
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rsync -avHAXR --numeric-ids --info=progress2 <username>@<ip-address>:/{lib,usr,opt/vc/lib} <rootfs-path>
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```
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On Linux, it is recommended to repair some symlinks which can be problematic:
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Navigate to the folder containing the symlinks first:
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```sh
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cd <rootfs_path>/usr/lib/arm-linux-gnueabihf
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```
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You can now use
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```sh
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readlink libpthread.so
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```
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which will show an absolute location of a shared library the symlinks points to. This location
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needs to be converted into a relative path.
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Run the following command to create a relative symlinks instead of an absolute ones. The pointed
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to location might change to check it with `readlink` first before removing the symlinks:
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```sh
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rm libpthread.so
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rm librt.so
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ln -s ../../../lib/arm-linux-gnueabihf/libpthread.so.0 libpthread.so
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ln -s ../../../lib/arm-linux-gnueabihf/librt.so.1 librt.so
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```
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For more information on issues which can occur when cloning the root filesystem,
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see the [troubleshooting](#troubleshooting) section.
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3. It is recommended to install `gdb-multiarch`. This tool will allow remote debugging
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on the host computer. This step is not required if the `tcf-agent` is used.
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```sh
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sudo apt-get install gdb-multiarch
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```
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4. Perform the steps [in the cross-compile section](#cross-test) to build the
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software for the Raspberry Pi and test it.
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## Cross-Compiling on a Windows Host
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### Additional Prerequites
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1. [MSYS2](https://www.msys2.org/) installed. All command line steps shown here
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were performed in the MSYS2 MinGW64 shell (not the default MSYS2, use MinGW64!).
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Replace `<UserName>` with respectively. It is recommended to set up
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aliases in the `.bashrc` file to allow quick navigation to the `fsfw_example`
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repository and to run `git config --global core.autocrlf true` for git in
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MinGW64.
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### Setting up prerequisites for Windows
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1. Install CMake and rsync in MinGW64 after installing MSYS2
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```
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pacman -S mingw-w64-x86_64-cmake rsync
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```
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2. Configure the Raspberry Pi linux environment. The last section of the
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[Linux REAMDE](README-linux.md#top) specifies how to set up a UNIX environment
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for the FSFW and isalso applicable to the Raspberry Pi. SSH into the
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Raspberry Pi and follow the instructions in that section.
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3. Install the correct [ARM Linux cross-compile toolchain provided by SysProgs](https://gnutoolchains.com/raspberry/).
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You can find out the distribution release of your Raspberry Pi by running `cat /etc/rpi-issue`.
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Test the toolchain by running:
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```sh
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arm-linux-gnueabihf-gcc --version
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```
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4. Set up a sysroot folder on the local host machine. Make sure the SSH connection to
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the Raspberry Pi is working without issues. Then perform the following steps
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```sh
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cd /c/Users/<UserName>
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mkdir raspberrypi
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cd raspberrypi
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mkdir rootfs
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cd rootfs
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pwd
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```
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Store the result of `pwd`, it is going to be used by `rsync` later.
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Now use rsync to clone the Rapsberry Pi sysroot to the local host machine.
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With a Raspberry Pi 4, you can replace `<ip-address>` with `raspberrypi.local`.
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Use the rootfs location stored from the previous steps as `<rootfs-path>`.
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```sh
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rsync -vR --progress -rl --delete-after --safe-links pi@<ip-address>:/{lib,usr,opt/vc/lib} <rootfs-path>
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```
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Please note that `rsync` sometimes does not copy shared libraries or symlinks properly,
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which might result in errors when cross-compiling and cross-linking. It is recommended to run
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the following commands in addition to the `rsync` command on Windows:
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```sh
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scp <user_name>@<ip-address>:/lib/arm-linux-gnueabihf/{libc.so.6,ld-linux-armhf.so.3,libm.so.6} <rootfs_path>/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/{libpthread.so,libc.so,librt.so} <rootfs_path>/usr/lib/arm-linux-gnueabihf
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```
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For more information on issues which can occur when cloning the root filesystem,
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see the [troubleshooting](#troubleshooting) section.
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5. It is recommended to install `gdb-multiarch`. This tool will allow remote debugging on the host
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computer. Replace `x86_64` with the correct processor architecture for other architectures.
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This is not required if the `tcf-agent` is used.
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```sh
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pacman -S mingw-w64-x86_64-gdb-multiarch
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```
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6. Perform the steps [in the following chapter](#cross-test) to build the
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software for the Raspberry Pi and test it.
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## <a id="cross-test"></a> Testing the cross-compilation
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It is recommended to set the following environmental variables for the CMake build:
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- `CROSS_COMPILE`: Explicitely specify the name of the cross compiler
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- `RASPBERRY_VERSION`: Explicitely specify the version of the Raspberry Pi
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- `RASPBIAN_ROOTFS`: Explicitely set the path to the local RPi rootfs
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For example with the following commands
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```sh
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export CROSS_COMPILE="arm-linux-gnueabihf"
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export RASPBERRY_VERSION="4"
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export RASPBIAN_ROOTFS="<pathToRootFS>"
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```
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It is recommended to test whether the environmental variables were set correctly,
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for example by running
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```sh
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echo $RASPBIAN_ROOTFS
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```
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These variables can either be set every time before a debugging session to
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keep the environment clean (should be done before starting Eclipse)
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or permanently by adding the `export` commands to system files.
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A helper script has been provided in `cmake/scripts/RPi` to perform
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setting up the environment. The scripts need to be `source`d instead of
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being run like regular shell scripts.
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You can also set up the environmental variables permanently by adding the
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export commands to the `.profile` or `.bashrc` file in the `$HOME` folder.
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On Windows, MinGW64 was used to set up the build system, so you can use the
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MinGW64 `.bashrc` file to do this. If you are using Eclipse to build
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the software, Eclipse will have the system variables from Windows,
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so it is recommended to either permanently set the three environmental
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variables in the Windows system environmental variables or add them in
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Eclipse. See the [Eclipse README](README-eclipse.md#top) for more information.
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Now we can test whether everything was set up properly by compiling the example
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and running it on the Raspberry Pi via command line.
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Navigate into the `fsfw_example` folder first.
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1. Build the software locally to test the cross-compilation process.
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We are going to create a Debug build directory first.
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```sh
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mkdir build-Debug-RPi
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cd build-Debug-RPi
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```
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2. Configure the build system. On Linux, run the following command:
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```sh
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cmake -G "Unix Makefiles" -DOS_FSFW=linux -DTGT_BSP=arm/raspberrypi -DLINUX_CROSS_COMPILE=ON -DCMAKE_BUILD_TYPE=Debug ..
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```
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On Windows, replace `-G "Unix Makefiles"` with `-G "MinGW Makefiles"`.
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Alternatively, you can use the helper shell scripts located inside `cmake/scripts/RPi/crosscompile`
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or the Python helper script `cmake_build_config.py` inside the `cmake/scripts` folder.
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The `RPi` folder also contains template shell files which can be `source`d
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to quickly set up the environmental variables if you want to keep the system path clean.
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3. Run the binary to test it
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```sh
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scp fsfw_example pi@raspberrypi.local:/home/pi/fsfw_example
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ssh pi@raspberrypi.local
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./fsfw_example
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```
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### Setting up Eclipse for a Raspberry Pi remote target
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It is recommended to use the provided Eclipse project files and
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launch configurations to have a starting point. See the specific section in
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the [Eclipse README](README-eclipse.md#top) for information how to do this.
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#### Windows
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There are some additional steps necessary on Windows: The cross-compiler by
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default is configured to look for the cross-compiler in `/opt/cross-pi-gcc/bin`.
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The toolchain path needs to be corrected, for example like shown in the following image:
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<img align="center" src="./images/eclipse/eclipse-cross-compile-win.png" width="50%">
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## Setting up the TCF agent on the Raspberry Pi
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It is recommended to set up a [TCF agent](https://wiki.eclipse.org/TCF) for comfortable
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Eclipse remote debugging. The following steps show how to setup the TCF agent
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on the Raspberry Pi and add it to the auto-startup applications. The steps are taken
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from [this guide](https://wiki.eclipse.org/TCF/Raspberry_Pi)
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1. Install required packages on the RPi
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```sh
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sudo apt-get install git uuid uuid-dev libssl-dev
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```
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2. Clone the repository and perform some preparation steps
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```sh
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git clone git://git.eclipse.org/gitroot/tcf/org.eclipse.tcf.agent.git
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cd org.eclipse.tcf.agent.git/agent
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```
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3. Build the TCF agent
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```sh
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make
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```
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and then test it by running
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```sh
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obj/GNU/Linux/arm/Debug/agent –S
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```
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4. Finally instal lthe agent for auto-start with the following steps and set it up for auto-start.
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The last step did not work on a Rapsberry Pi 4, but apparentely was not necessary.
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```sh
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cd org.eclipse.tcf.agent/agent
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make install
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sudo make install INSTALLROOT=
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sudo update-rc.d tcf-agent defaults
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sudo update-rc.d tcf-agent enable 2
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```
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The [Eclipse README](README-eclipse.md#top) specifies how to perform remote
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debugging using the TCF agent.
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# <a id="troubleshooting"></a> Troubleshooting
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## Cloning the root filesystem
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There might be some issues with the pthread symbolic links.
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Navigate to the folder containing the symlinks
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```sh
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cd <rootfs_path>/usr/lib/arm-linux-gnueabihf
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```
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Type `more libpthread`, press `TAB` and check whether the symbolic
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link `libpthread.so` is shown. If it is not, we are going to set it up
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manually to avoid issues when linking against `pthread` later.
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Now you can find out where `libpthread.so` points with `readlink libpthread.so`.
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This information is used to convert the absolute symlink to relative ones, for example with:
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Run the following command to copy the symlink `libpthread.so.0` if it does not exist yet:
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```sh
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/libpthread.so .
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```
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Alternatively, you can correct the symlinks to use relative paths, for example with:
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```sh
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ln -s ../../../lib/arm-linux-gnueabihf/libpthread.so.0 libpthread.so
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ln -s ../../../lib/arm-linux-gnueabihf/librt.so.1 librt.so
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```
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Please note that there might also be issues with some symlinks or libraries not being copied
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properly, especially on Windows. This has occured with files like `libc.so.6`.
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If there are linker issues at a later stage, you can try to copy the symlinks manually from the
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Linux board to the sysroot with `scp`.
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For example, you can copy `libc.so.6` from the Linux board to the sysroot with
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the following command
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If there are issues with the cross-compilation process, manually copying the following
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symlinks can help:
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```sh
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/libc.so <rootfs_path>/usr/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/libc.a <rootfs_path>/usr/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/librt.a <rootfs_path>/usr/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/usr/lib/arm-linux-gnueabihf/librt.so <rootfs_path>/usr/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/lib/arm-linux-gnueabihf/librt.so.1 <rootfs_path>/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/lib/arm-linux-gnueabihf/libpthread.so.0 <rootfs_path>/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/lib/arm-linux-gnueabihf/ld-linux-armhf.so.3 <rootfs_path>/lib/arm-linux-gnueabihf
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scp <user_name>@<ip-address>:/lib/arm-linux-gnueabihf/libc.so.6 <rootfs_path>/lib/arm-linux-gnueabihf
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```
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If any custom libraries are used which rely on symlinks, it might be necessary to copy them
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or create them manually as well.
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