The GNU MCU Eclipse RISC-V Embedded GCC build
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.

GNU MCU Eclipse RISC-V Embedded GCC - the build scripts

These are the scripts and additional files required to build the GNU MCU Eclipse RISC-V Embedded GCC.

This release follows the official RISC-V distribution maintained by SiFive, as part of the riscv/riscv-gnu-toolchain project.

The build scripts use the xPack Build Box (XBB), a set of elaborate build environments based on GCC 7.2 (Docker containers for GNU/Linux and Windows or a custom HomeBrew for MacOS).


Compared to the original RISC-V version, there are no functional changes; the same architecture and API options are supported, and the same combinations of libraries (derived from newlib) are provided.


The only notable addition is support for newlib-nano, using the --specs=nano.specs option. For better results, this option must be added to both compile and link time (the next release of the GNU MCU Eclipse plug-ins will add support for this).

If no syscalls are needed, --specs=nosys.specs can be used at link time to provide empty implementations for the POSIX system calls.

The libraries are compiled with -O2 -mcmodel=medany.


Similarly to the ARM binary distribution, a separate version GDB with Python support was added. To run it, a functional Python must be available.


Another addition compared to the SiFive distribution is the presence of the documentation, including the PDF manuals for all tools.

How to build


The prerequisites are common to all binary builds. Please follow the instructions in the separate Prerequisites for building binaries page and return when ready.

Download the build scripts repo

The build script is available from GitHub and can be viewed online.

To download it, clone the gnu-mcu-eclipse/riscv-none-gcc-build Git repo, including submodules.

$ rm -rf ~/Downloads/riscv-none-gcc-build.git
$ git clone --recurse-submodules \

Check the script

The script creates a temporary build Work/riscv-none-gcc-${version} folder in the user home. Although not recommended, if for any reasons you need to change this, you can redefine WORK_FOLDER_PATH variable before invoking the script.

Preload the Docker images

Docker does not require to explicitly download new images, but does this automatically at first use.

However, since the images used for this build are relatively large, it is recommended to load them explicitly before starting the build:

$ bash ~/Downloads/riscv-none-gcc-build.git/scripts/ preload-images

The result should look similar to:

$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ilegeul/centos32    6-xbb-v1            f695dd6cb46e        2 weeks ago         2.92GB
ilegeul/centos      6-xbb-v1            294dd5ee82f3        2 weeks ago         3.09GB
hello-world         latest              f2a91732366c        2 months ago        1.85kB

Update git repos

The GNU MCU Eclipse RISC-V GCC is generally following the official RISC-V releases, with as little differences as possible.

The procedure is to first merge the remote branches to the local branches.

Currently, the following branches are used

  • riscv-gcc-7.2.0
  • riscv-newlib-2.5.0
  • riscv-binutils-2.29

The GNU MCU Eclipse branches have similar names, but suffixed with -gme.

After merging the remote branches, merge the result into the -gme branch.

Prepare release

To prepare a new release, first determine the GCC version (like 7.2.0) and update the scripts/VERSION file. The format is 7.2.0-3. The fourth digit is the GNU MCU Eclipse release number of this version.

Add a new set of definitions in the scripts/, with the versions of various components.

Update CHANGELOG.txt

Check riscv-none-gcc-build.git/CHANGELOG.txt and add the new release.


Although it is perfectly possible to build all binaries in a single step on a macOS system, due to Docker specifics, it is faster to build the GNU/Linux and Windows binaries on a GNU/Linux system and the macOS binary separately.

Build the GNU/Linux and Windows binaries

The current platform for GNU/Linux and Windows production builds is an Ubuntu 17.10 VirtualBox image running on a macMini with 16 GB of RAM and a fast SSD.

Before starting a multi-platform build, check if Docker is started:

$ docker info

To build both the 32/64-bits Windows and GNU/Linux versions, use --all; to build selectively, use --linux64 --win64 or --linux32 --win32 (GNU/Linux can be built alone; Windows also requires the GNU/Linux build).

$ bash ~/Downloads/riscv-none-gcc-build.git/scripts/ --all

To build one of the previous versions:

$ RELEASE_VERSION=7.2.0-3 bash ~/Downloads/riscv-none-gcc-build.git/scripts/ --all

Several hours later, the output of the build script is a set of 4 files and their SHA signatures, created in the deploy folder:

$ ls -l deploy
total 495652
-rw-r--r-- 1 ilg ilg 126668466 May  7 13:51 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-centos32.tgz
-rw-r--r-- 1 ilg ilg       132 May  7 13:51 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-centos32.tgz.sha
-rw-r--r-- 1 ilg ilg 123374305 May  7 11:26 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-centos64.tgz
-rw-r--r-- 1 ilg ilg       132 May  7 11:26 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-centos64.tgz.sha
-rw-r--r-- 1 ilg ilg 123243494 May  7 14:27
-rw-r--r-- 1 ilg ilg       129 May  7 14:27
-rw-r--r-- 1 ilg ilg 134171799 May  7 12:04
-rw-r--r-- 1 ilg ilg       129 May  7 12:04

To copy the files from the build machine to the current development machine, open the deploy folder in a terminal and use scp:

$ cd ${HOME}/Work/riscv-none-gcc-7.2.0-3/deploy
$ scp * ilg@ilg-mbp.local:Downloads

Build the macOS binary

The current platform for macOS production builds is a macOS 10.10.5 VirtualBox image running on the same macMini with 16 GB of RAM and a fast SSD.

To build the latest macOS version, with the same timestamp as the previous build:

$ caffeinate bash ~/Downloads/riscv-none-gcc-build.git/scripts/ --osx --date YYYYMMDD-HHMM

To build one of the previous macOS versions:

$ RELEASE_VERSION=7.2.0-3 caffeinate bash ~/Downloads/riscv-none-gcc-build.git/scripts/ --osx --date YYYYMMDD-HHMM

For consistency reasons, the date should be the same as the GNU/Linux and Windows builds.

Several hours later, the output of the build script is a compressed archive and its SHA signature, created in the deploy folder:

$ ls -l deploy
total 238824
-rw-r--r--  1 ilg  staff  122271403 May  7 01:36 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-macos.tgz
-rw-r--r--  1 ilg  staff        129 May  7 01:36 gnu-mcu-eclipse-riscv-none-gcc-7.2.0-3-20180506-1300-macos.tgz.sha

To copy the files from the build machine to the current development machine, open the deploy folder in a terminal and use scp:

$ cd ${HOME}/Work/riscv-none-gcc-7.2.0-3/deploy
$ scp * ilg@ilg-mbp.local:Downloads

Subsequent runs

Separate platform specific builds

Instead of --all, you can use any combination of:

--win32 --win64 --linux32 --linux64

Please note that, due to the specifics of the GCC build process, the Windows build requires the corresponding GNU/Linux build, so --win32 alone is equivalent to --linux32 --win32 and --win64 alone is equivalent to --linux64 --win64.


To remove most build files, use:

$ bash ~/Downloads/riscv-none-gcc-build.git/scripts/ clean

To also remove the repository and the output files, use:

$ bash ~/Downloads/riscv-none-gcc-build.git/scripts/ cleanall

For production builds it is recommended to completely remove the build folder.


For performance reasons, the actual build folders are internal to each Docker run, and are not persistent. This gives the best speed, but has the disadvantage that interrupted builds cannot be resumed.

For development builds, it is possible to define the build folders in the host file system, and resume an interrupted build.


For development builds, it is also possible to create everything with -g -O0 and be able to run debug sessions.

Interrupted builds

The Docker scripts run with root privileges. This is generally not a problem, since at the end of the script the output files are reassigned to the actual user.

However, for an interrupted build, this step is skipped, and files in the install folder will remain owned by root. Thus, before removing the build folder, it might be necessary to run a recursive chown.


The procedure to install GNU MCU Eclipse RISC-V Embedded GCC is platform specific, but relatively straight forward (a .zip archive on Windows, a compressed tar archive on macOS and GNU/Linux).

A portable method is to use xpm:

$ xpm install @gnu-mcu-eclipse/riscv-none-gcc --global

More details are available on the How to install the RISC-V toolchain? page.

After install, the package should create a structure like this (only the first two depth levels are shown):

$ tree -L 2 /Users/ilg/Library/xPacks/\@gnu-mcu-eclipse/riscv-none-gcc/7.2.0-3.1/.content/
├── bin
│   ├── libgcc_s.1.dylib
│   ├── libstdc++.6.dylib
│   ├── riscv-none-embed-addr2line
│   ├── riscv-none-embed-ar
│   ├── riscv-none-embed-as
│   ├── riscv-none-embed-c++
│   ├── riscv-none-embed-c++filt
│   ├── riscv-none-embed-cpp
│   ├── riscv-none-embed-elfedit
│   ├── riscv-none-embed-g++
│   ├── riscv-none-embed-gcc
│   ├── riscv-none-embed-gcc-7.2.0
│   ├── riscv-none-embed-gcc-ar
│   ├── riscv-none-embed-gcc-nm
│   ├── riscv-none-embed-gcc-ranlib
│   ├── riscv-none-embed-gcov
│   ├── riscv-none-embed-gcov-dump
│   ├── riscv-none-embed-gcov-tool
│   ├── riscv-none-embed-gdb
│   ├── riscv-none-embed-gdb-py
│   ├── riscv-none-embed-gprof
│   ├── riscv-none-embed-ld
│   ├── riscv-none-embed-ld.bfd
│   ├── riscv-none-embed-nm
│   ├── riscv-none-embed-objcopy
│   ├── riscv-none-embed-objdump
│   ├── riscv-none-embed-ranlib
│   ├── riscv-none-embed-readelf
│   ├── riscv-none-embed-size
│   ├── riscv-none-embed-strings
│   └── riscv-none-embed-strip
├── gnu-mcu-eclipse
│   ├── CHANGELOG.txt
│   ├── licenses
│   ├── patches
│   └── scripts
├── include
│   └── gdb
├── lib
│   ├── gcc
│   ├──
│   └── ->
├── riscv-none-embed
│   ├── bin
│   ├── include
│   ├── lib
│   └── share
└── share
    ├── doc
    └── gcc-riscv-none-embed

17 directories, 35 files

No other files are installed in any system folders or other locations.


The binaries are distributed as portable archives; thus they do not need to run a setup and do not require an uninstall.


A simple test is performed by the script at the end, by launching the executable to check if all shared/dynamic libraries are correctly used.

For a true test you need to first install the package and then run the program from the final location. For example on macOS the output should look like:

$ /Users/ilg/Library/xPacks/\@gnu-mcu-eclipse/riscv-none-gcc/7.2.0-3.1/.content/bin/riscv-none-embed-gcc --version
riscv-none-embed-gcc (GNU MCU Eclipse RISC-V Embedded GCC, 64-bits) 7.2.0


For issues related to the procedure used to build the GNU MCU Eclipse RISC-V Embedded GCC binaries, please report them via gnu-mcu-eclipse/riscv-none-gcc-build GitHub Issues.

For issues related to the xPack used to install the binaries, please report them via gnu-mcu-eclipse/riscv-none-gcc-xpack GitHub issues.

For issues related to the toolchain functionality (compiler, newlib gdb, etc) please report them via their original RISC-V projects:

More build details

The build process is split into several scripts. The build starts on the host, with, which runs several times, once for each target, in one of the two docker containers. Both scripts include several other helper scripts. The entire process is quite complex, and an attempt to explain its functionality in a few words would not be realistic. Thus, the authoritative source of details remains the source code.