Added mechanisms for building a cross-compiler, that can build for the raspberry pi 0 W.

.gitignore

@@ -1,5 +1,5 @@
 
-/build
+/build*
 
 # ---> C++
 # Prerequisites

conanfile.py

@@ -10,7 +10,7 @@ class BmrConan(ConanFile):
 
     def configure(self):
         self.options["boost"].without_cobalt = True
-        if self.settings.arch == "armv7":
+        if self.settings.arch == "armv7" or self.settings.arch == "armv6":
             self.options["libpng"].neon = False
 
 

support/create-cross-compiler/README.md

@@ -0,0 +1,17 @@
+# Creating cross-compilers
+This folder contains configuration, scripts and docker images that are used for creating cross-compilers. The intended use case is to build C and C++ software for various platforms. Docker is being used to provide a common environment and isolating the build process.
+
+## How to use:
+1. Clone the repository to a location of your liking.
+2. Create a docker image containing crosstool-ng.
+   ``cd support/create-cross-compiler``
+   ``docker build -t <docker image name> -f create-cross-compiler.Dockerfile .``
+3. Use the docker image to create the cross comiler.
+   * Configuration needs to be provided. (environment variable: CROSS_TARGET_INFO_PATH).
+   * Destination location needs to be provided (environment variable: CROSS_TARGET_DST_PATH).
+   * Use docker volume functionality to link directories to the docker container.
+   ``docker run -ti -e CROSS_TARGET_INFO_PATH=/config -e CROSS_TARGET_DST_PATH=/dst -v ./armv6-rpi-linux:/config -v ./dst:/dst <docker image name>``
+
+
+
+

support/create-cross-compiler/armv6-rpi-linux/conan_profile

@@ -0,0 +1,12 @@
+[settings]
+os=Linux
+arch=armv6
+compiler=gcc
+build_type=Release
+compiler.cppstd=gnu17
+compiler.libcxx=libstdc++11
+compiler.version=14
+[buildenv]
+CC=/x-tools/armv6-rpi-linux-gnueabihf/bin/armv6-rpi-linux-gnueabihf-gcc
+CXX=/x-tools/armv6-rpi-linux-gnueabihf/bin/armv6-rpi-linux-gnueabihf-g++
+LD=/x-tools/armv6-rpi-linux-gnueabihf/bin/armv6-rpi-linux-gnueabihf-ld

support/create-cross-compiler/create-cross-compiler-armv6-rpi-linux.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+mkdir -p ../../build-tools/x-tools
+
+docker build \
+    -t bmr-create-cross-compiler \
+    -f create-cross-compiler.Dockerfile .
+
+docker run -ti \
+    -e CROSS_TARGET_INFO_PATH=/extern-config \
+    -e CROSS_TARGET_DST_PATH=/extern-dst \
+    -v ./armv6-rpi-linux:/extern-config \
+    -v ../../build-tools/x-tools:/extern-dst bmr-create-cross-compiler

support/create-cross-compiler/create-cross-compiler.Dockerfile

@@ -0,0 +1,89 @@
+FROM alpine:3.22.2
+
+# Install packages needed in both building and running.
+RUN apk update && \
+    apk add --no-cache \
+    libstdc++
+
+# Install tools required for building.
+RUN mkdir -p /root/.local/bin
+ENV PATH="${PATH}:/root/.local/bin"
+
+RUN apk add --no-cache \
+    autoconf \
+    bash \
+    binutils \
+    build-base \
+    cmake \
+    clang \
+    clang-extra-tools \
+    gdb \
+    git \
+    libtool \
+    linux-headers \
+    ninja \
+    m4 \
+    perl \
+    python3 \
+    pipx
+
+# Install tools we need for building the cross compiler.
+RUN apk add --no-cache \
+    gpg \
+    gpg-agent \
+    automake \
+    flex \
+    make \
+    texinfo \
+    xz \
+    help2man \
+    gawk \
+    bison \
+    ncurses-dev \
+    rsync \
+    wget
+
+RUN mkdir -p /workspace
+WORKDIR /workspace
+
+# Download crosstool-ng that we use to build the cross compiler.
+RUN <<EOF
+    gpg --keyserver pgp.surfnet.nl --recv-keys 721B0FB1CDC8318AEBB888B809F6DD5F1F30EF2E
+    wget http://crosstool-ng.org/download/crosstool-ng/crosstool-ng-1.28.0.tar.bz2.sig
+    wget http://crosstool-ng.org/download/crosstool-ng/crosstool-ng-1.28.0.tar.bz2
+    gpg --verify crosstool-ng-1.28.0.tar.bz2.sig
+    tar -xjf crosstool-ng-1.28.0.tar.bz2
+    mv /workspace/crosstool-ng-1.28.0 /crosstool
+EOF
+
+# - Add a user that we need for building (crosstool-ng requires non-root user for that).
+# - Add some directories we need in the future for building.
+# - Build crosstool-ng, which in it's turn will be used to build the cross compiler.
+
+ENV CROSS_DESTDIR=/x-tools
+
+WORKDIR /crosstool
+RUN <<EOF
+    adduser -D crosstoolng    
+
+    mkdir -p /home/crosstoolng/src
+    mkdir -p $CROSS_DESTDIR
+
+    ./bootstrap
+    ./configure
+    make DESTDIR=$CROSS_DESTDIR
+    make install
+
+    chown -R crosstoolng:crosstoolng /crosstool
+    chown -R crosstoolng:crosstoolng $CROSS_DESTDIR
+    chown -R crosstoolng:crosstoolng /home/crosstoolng
+EOF
+
+# We now have crosstool-ng built and ready to be used for building the cross-compiler that we actually want. To
+# do that we need to feed some configuration
+
+WORKDIR /workspace
+ADD --chmod=544 ./scripts/create-cross-compiler.py . 
+ADD --chmod=544 ./scripts/entrypoint.sh . 
+
+ENTRYPOINT ["./entrypoint.sh"]

support/create-cross-compiler/scripts/create-cross-compiler.py

@@ -0,0 +1,45 @@
+#! /usr/bin/python
+import argparse
+import json
+import os
+import shutil
+import subprocess
+import sys
+
+def runcmd(command):
+    print('RUN ' + command)
+    process = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True)
+    for line in iter(process.stdout.readline, b''):  # b'' indicates EOF
+        print(line.decode('utf-8'), end='')
+
+def load_environment(filename):
+    with open(filename) as f:
+        return json.load(f)
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument('--cross-target-info-path', dest='target_info')
+parser.add_argument('--cross-destination-path', dest='dst')
+args = parser.parse_args()
+
+cross_target_info_path    = args.target_info
+cross_destination_path    = args.dst
+ctng_config               = cross_target_info_path + '/ct-ng.config'
+cross_destdir             = os.environ['CROSS_DESTDIR']
+
+if not os.path.isdir(cross_destdir):
+    raise Exception("ERROR... expected internal destination for ct-ng does not exist")
+if not os.path.isdir(cross_target_info_path):
+    raise Exception("Supplied configuration info path is not a directory")
+if not os.path.isfile(ctng_config):
+    raise Exception("No crosstool ng configuration file found (ct-ng.config)")
+
+shutil.copy(ctng_config, '/crosstool/.config')
+os.chdir('/crosstool')
+
+runcmd("su crosstoolng -c 'ct-ng source'")
+runcmd("su crosstoolng -c 'ct-ng build'")
+
+runcmd("cp -rv " + cross_destdir + "/* " + cross_destination_path + "/")
+
+sys.exit(0)

support/create-cross-compiler/scripts/entrypoint.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+./create-cross-compiler.py --cross-target-info-path=$CROSS_TARGET_INFO_PATH --cross-destination-path=$CROSS_TARGET_DST_PATH
+