ARM Linux (Soft-Float)

This guide covers cross-compiling Pony programs from an x86-64 Linux host to 32-bit ARM Linux (glibc, soft-float ABI). This targets ARMv7-A devices using software floating point. If your target uses hardware floating point, see ARM Linux (Hard-Float) instead.

Install the Cross-Toolchain

On Debian/Ubuntu, install the ARM cross-compiler and QEMU for testing:

sudo apt-get install gcc-arm-linux-gnueabi g++-arm-linux-gnueabi qemu-user

This provides the cross-compiler for building the Pony runtime. The sysroot location varies by distribution. On Debian/Ubuntu, it’s typically at /usr/arm-linux-gnueabi/ or /usr/local/arm-linux-gnueabi/libc/. ponyc searches both locations automatically.

Build the Cross-Compiled Runtime

The Pony runtime needs to be compiled for ARM. This requires the ponyc source tree with a full build environment. See the cross-compilation overview for the initial setup.

From the ponyc source directory:

make cross-libponyrt config=release \
  CC=arm-linux-gnueabi-gcc \
  CXX=arm-linux-gnueabi-g++ \
  arch=armv7-a \
  cross_cflags="-march=armv7-a -mtune=cortex-a9" \
  cross_lflags="-O3;-march=arm"

The output lands in build/armv7-a/release/.

Compile a Pony Program

Create a simple test program:

mkdir hello && cat > hello/main.pony << 'EOF'
actor Main
  new create(env: Env) =>
    env.out.print("Hello from ARM!")
EOF

Compile it for ARM:

PONYPATH=build/armv7-a/release ponyc \
  --triple=arm-unknown-linux-gnueabi \
  --cpu=cortex-a9 \
  --link-arch=armv7-a \
  --sysroot=/usr/arm-linux-gnueabi \
  hello

This produces a hello binary in the current directory.

Verify with QEMU

Run the cross-compiled binary using QEMU user-mode emulation:

qemu-arm -cpu cortex-a9 -L /usr/arm-linux-gnueabi/ ./hello

You should see:

Hello from ARM!

The -cpu flag tells QEMU which CPU to emulate, and -L points to the target’s shared libraries. Adjust the -L path if your sysroot is in a different location (e.g., /usr/local/arm-linux-gnueabi/libc).