BareMetal-newlib4

based on BareMetal-newlib

This port was created by effbiae

Introduction

This repository contains the files, script, and instructions necessary to build the newlib C library for BareMetal OS. The latest version of Newlib as of this writing is 4.4.0.20231231

newlib gives BareMetal OS access to the standard set of C library calls like printf(), scanf(), memcpy(), etc.

These instructions are for executing on a 64-bit Linux host. Building on a 64-bit host saves us from the steps of building a cross compiler. The latest distribution of Ubuntu was used while writing this document.

Building Details

You will need the following Linux packages. Use your prefered package manager to install them:

libtool sed gawk bison flex m4 texinfo texi2html unzip make

You also need exact versions of the following:

• autoconf - 2.69
• automake - 1.15.1

On a Debian-based system this can be accomplished via the following:

# Remove software if already installed
sudo apt remove autoconf automake

# Download the required versions 
wget https://ftp.gnu.org/gnu/autoconf/autoconf-2.69.tar.gz
wget https://ftp.gnu.org/gnu/automake/automake-1.15.1.tar.gz

# Extract them
tar -xvzf autoconf-2.69.tar.gz
tar -xvzf automake-1.15.1.tar.gz

# Build and install them
cd autoconf-2.69
./configure
make
sudo make install
cd ..
cd automake-1.15.1
./configure
make
sudo make install
cd ..

# Adjust the path variable
PATH=$PATH:/usr/local/bin

Run the build script to download, patch and build:

./build-newlib.sh

After a lengthy compile you should have newlib installed in ./output and test.app built.

./output/x86_64-pc-baremetal/lib/libc.a is the compiled C library that is ready for linking. ./output/x86_64-pc-baremetal/lib/crt0.o is the starting binary stub for your program.

./build-newlib.sh compiles test.app as

gcc -I output/x86_64-pc-baremetal/include/ -c test.c -o test.o
ld -T app.ld -o test.app test.o output/x86_64-pc-baremetal/lib/libc.a

By default libc.a will be about 6.4 MiB. You can strip it to make it a little more compact. strip can decrease it to about 1.4 MiB.

strip --strip-debug output/x86_64-pc-baremetal/lib/libc.a