Build an example application with C++

This document explains how to build a C++ application using musl libC for morello and morello-sdk.

Usage

Create the following workspace structure:

cpp/
  |-> workspace/
       |-> sysroot.env
       |-> helloworld/
            |-> Makefile
            |-> main.cpp
  |-> docker-compose.yml

Create a docker-compose.yml file in cpp/ as follows:

# Docker composer file for Morello LTP
version: '3.8'
services:
  cpp-morello-sdk:
    image: "git.morello-project.org:5050/morello/morello-sdk/morello-sdk:latest"
    container_name: "cpp-morello-sdk"
    volumes:
      - ./workspace:/home/morello/workspace
    tty: true
    restart: unless-stopped

Then, bring up the container (from cpp/):

$ docker-compose up -d

Note: It is important to update always to the latest version of the morello-sdk. If you are unsure on which version you are running instead of the command above execute:

$ docker-compose pull
$ docker-compose up -d

Create a sysroot.env file as follows:

export MUSL_HOME="/morello/musl"
export MUSL_RPATH="${MUSL_HOME}/lib"

Enter helloworld/ and edit the Makefile inserting the code below:

# SPDX-License-Identifier: BSD-3-Clause

# This Makefile will compile an helloworld application using Morello Clang and the Musl libc compiled for purecap.

CXX=clang++
# ELF_PATCH is used to check that the correct elf flag for Morello is present
ELF_PATCH=morello_elf
MUSL_HOME?=/morello/musl
MUSL_RPATH?=$(MUSL_HOME)/lib
CLANG_RESOURCE_DIR=$(shell clang -print-resource-dir)

OUT=./bin
# we want the same result no matter where we're cross compiling (x86_64, aarch64)
TARGET?=aarch64-linux-musl_purecap
CPPFLAGS=-lunwind -lc++abi

all:
	mkdir -p $(OUT)
	$(CXX) -c -g -march=morello -mabi=purecap \
		--target=$(TARGET) --sysroot $(MUSL_HOME) \
		main.cpp -o $(OUT)/morello-helloworld.cpp.o

	# Use -static to build a static binary and remove "-Wl,--dynamic-linker=$(MUSL_RPATH)/libc.so" and "-Wl,-rpath,$(MUSL_RPATH)"
	$(CXX) -fuse-ld=lld -march=morello -mabi=purecap \
		--target=$(TARGET) --sysroot $(MUSL_HOME) \
		$(CPPFLAGS) \
		-rtlib=compiler-rt \
		$(OUT)/morello-helloworld.cpp.o \
		-o $(OUT)/morello-helloworld-c++ \
		-Wl,--dynamic-linker=$(MUSL_RPATH)/libc.so -v \
		-Wl,-rpath,$(MUSL_RPATH)
	$(ELF_PATCH) $(OUT)/morello-helloworld-c++
	rm $(OUT)/morello-helloworld.cpp.o

clean:
	rm $(OUT)/morello-helloworld-c++

Edit main.cpp and insert the code below:

/* SPDX-License-Identifier: BSD-3-Clause */

#include <iostream>

int main(int argc, char **argv)
{ 
    std::cout << "Hello from Morello!!" << std::endl;

	return 0;
}

To enter into the container, run the command:

$ docker exec -it -u root cpp-morello-sdk /bin/bash

At this point you have everything you need. Source the development kit environment file:

source /morello/env/morello-sdk
source ../sysroot.env

and run:

make

If everything went well your morello-helloworld-c++ binary for morello should be waiting for you in workspace/cpp/bin.

Have a lot of fun!

Note (1): make can be substituted with make -j<N> where N is the number of cores.
Note (2): Once you started the docker container the files of your project are accessible at /home/morello/workspace/cpp.

For further information please refer to the Docker documentation.

Docs

Build an example application with C++

Usage