Is there a way to cross-compile for armv6 using gcc-7?

Question

I am trying to cross-compile for raspberry B/raspberry zero on ubuntu18.04 using crossbuild-essential-armhf. I installed it using :

apt-get install -y crossbuild-essential-armhf

In order to test I am using a simple hello world file hello.c:

#include <stdio.h> 
int main() {
        printf("hello\n");
        return 0; 
}

Using :

arm-linux-gnueabihf-gcc hello.c

The executable crash with segmentation violation, the stack is then :

#0  0x0044f5c2 in ?? ()
#1  0x0040040e in _start ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

So I tried to build using different commands searching on internet like :

arm-linux-gnueabihf-gcc -marm -march=armv6 hello.c
arm-linux-gnueabihf-gcc -marm -mcpu=arm1176jzf-s hello.c
arm-linux-gnueabihf-gcc -marm -march=armv6 -mfpu=vfp -mfloat-abi=hard hello.c

But the stack is always the same.

Using the "historical" https://github.com/raspberrypi/tools.git is working but this gcc-4.8 compiler is far too old to compile modern code.

Is there a way to produce raspberry B/raspberry zero binaries using a gcc-7 cross compiler ?

Answer 1

I ran into a similar issue trying to cross-compile code for the Raspberry PI Zero (armv6) using a newer GCC 8.

Current toolchains are often not built with the --with-arch=armv6 flag. This results in binaries which are not compatible with armv6 and therefore you may get Illegal Instruction error.

I created a github repo where you can download a toolchain based on a current GCC version for the Raspi Zero (and also for all the other RasPI)

https://github.com/Pro/raspi-toolchain

Answer 2

Using the compiler toolchain from https://sourceforge.net/projects/raspberry-pi-cross-compilers/

For pizero the cross-compiler is available from the link cross-gcc-9.1.0-pi_0-1.tar.gz

This compiler version is :

Using built-in specs.
COLLECT_GCC=/opt/cross-pi-gcc-9.1.0-0/bin/arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/opt/cross-pi-gcc-9.1.0-0/bin/../libexec/gcc/arm-linux-gnueabihf/9.1.0/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../configure --prefix= --target=arm-linux-gnueabihf --enable-languages=c,c++,fortran --with-sysroot=/arm-linux-gnueabihf/libc --with-build-sysroot=/opt/cross-pi-gcc-9.1.0-0/arm-linux-gnueabihf/libc --with-arch=armv6 --with-fpu=vfp --with-float=hard --disable-multilib
Thread model: posix
gcc version 9.1.0 (GCC)

Building with :

arm-linux-gnueabihf-gcc hello.c

build an executable that run on raspberry zero.

Answer 3

The problem is that command line architecture flags change the behavior of the compiler, but they don't change the precompiled runtime support code that is linked in to every executable.

So when you try to build armv6 binaries with a toolchain that is built for armv7, they don't work.

Answer 4

If you need to build static binaries without any dependencies, you can use the toolchains at https://musl.cc/. I've managed to successfully build (on WSL, Ubuntu 18.04) with this toolchain: https://more.musl.cc/9.2.1/x86_64-linux-musl/ with settings -march=armv6zk -mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mfpu=vfp

Answer 5

Here's what I do for C++

sudo apt-get install build-essential
sudo apt-get install g++-arm-linux-gnueabihf
sudo apt-get install gdb-multiarch

then arm-linux-gnueabihf-g++ -v to test the installation.

After that, open "testing.cpp" and put in

#include <iostream>
using namespace std;

int main() 
{
    cout << "Hello, World!";
    return 0;
}

Finally,

arm-linux-gnueabihf-g++ -O3 -g3 -Wall -c -o -fPIC "hello.o" "hello.cpp"
arm-linux-gnueabihf-g++ -o "hello" hello.o

Check the binary to make sure it's been compiled correctly: file hello should yield hello: ELF 32-bit LSB executable,ARM, EABI5 version 1 (SYSV)... The ARM is what you're looking for. If it's present, you're good to go.

Answer 6

All answers are great! But ensure that you are using the latest cross-compiler 10.2.0

For setting up your environment see this .. Cross Compiler: Installation Instructions

GCC provides great documentation for ARM devices and which flags work best (GCC documentation)

Create a hello.c file for hello world and try this:

arm-linux-gnueabihf-gcc hello.c -march=armv6 -mfpu=vfp -mfloat-abi=hard -o rpi-hello.so