15.2. Project Sets

The RTEMS Source Builder supports project configurations. Project configurations can be public or private and can be contained in the RTEMS Source Builder project if suitable.

The configuration file loader searches the macro _configdir and by default this is set to %{_topdir}/config:%{_sbdir}/config where _topdir is your current working directory, or the directory you invoke the RTEMS Source Builder command in. The macro _sbdir is the directory where the RTEMS Source Builder command resides. Therefore the config directory under each of these is searched so all you need to do is create a config in your project and add your configuration files. They do not need to be under the RTEMS Source Builder source tree. Public projects are included in the main RTEMS Source Builder such as RTEMS.

You can add your own patches directory next to your config directory as the %patch command searches the _patchdir macro variable and it is by default set to %{_topdir}/patches:%{_sbdir}/patches.

The source-builder/config directory provides generic scripts for building various tools. You can specialise these in your private configurations to make use of them. If you add new generic configurations please contribute them back to the project

Build sets can be controlled via the command line to enable (--with-<feature>) and disable (--without-<feature>) various features. There is no definitive list of build options that can be listed because they are implemented with the configuration scripts. The best way to find what is available is to grep the configuration files for with and without.

15.2.1. Bare Metal

The RSB contains a bare configuration tree and you can use this to add packages you use on the hosts. For example ‘qemu’ is supported on a range of hosts. RTEMS tools live in the rtems/config directory tree. RTEMS packages include tools for use on your host computer as well as packages you can build and run on RTEMS.

The bare metal support for GNU Tool chains. An example is the lang/gcc491 build set. You need to provide a target via the command line --target option and this is in the standard 2 or 3 tuple form. For example for an ARM compiler you would use arm-eabi or arm-eabihf, and for SPARC you would use sparc-elf:

$ cd rtems-source-builder/bare
$ ../source-builder/sb-set-builder --log=log_arm_eabihf \
    --prefix=$HOME/development/bare --target=arm-eabihf lang/gcc491
RTEMS Source Builder - Set Builder, v0.3.0
Build Set: lang/gcc491
config: devel/expat-2.1.0-1.cfg
package: expat-2.1.0-x86_64-apple-darwin13.2.0-1
building: expat-2.1.0-x86_64-apple-darwin13.2.0-1
config: devel/binutils-2.24-1.cfg
package: arm-eabihf-binutils-2.24-1
building: arm-eabihf-binutils-2.24-1
config: devel/gcc-4.9.1-newlib-2.1.0-1.cfg
package: arm-eabihf-gcc-4.9.1-newlib-2.1.0-1
building: arm-eabihf-gcc-4.9.1-newlib-2.1.0-1
config: devel/gdb-7.7-1.cfg
package: arm-eabihf-gdb-7.7-1
building: arm-eabihf-gdb-7.7-1
installing: expat-2.1.0-x86_64-apple-darwin13.2.0-1 -> /Users/chris/development/bare
installing: arm-eabihf-binutils-2.24-1 -> /Users/chris/development/bare
installing: arm-eabihf-gcc-4.9.1-newlib-2.1.0-1 -> /Users/chris/development/bare
installing: arm-eabihf-gdb-7.7-1 -> /Users/chris/development/bare
cleaning: expat-2.1.0-x86_64-apple-darwin13.2.0-1
cleaning: arm-eabihf-binutils-2.24-1
cleaning: arm-eabihf-gcc-4.9.1-newlib-2.1.0-1
cleaning: arm-eabihf-gdb-7.7-1

15.2.2. RTEMS

The RTEMS Configurations are found in the rtems directory. The configurations are grouped by RTEMS version and a release normally only contains the configurations for that release.. In RTEMS the tools are specific to a specific version because of variations between Newlib and RTEMS. Restructuring in RTEMS and Newlib sometimes moves libc functionality between these two parts and this makes existing tools incompatible with RTEMS.

RTEMS allows architectures to have different tool versions and patches. The large number of architectures RTEMS supports can make it difficult to get a common stable version of all the packages. An architecture may require a recent GCC because an existing bug has been fixed, however the more recent version may have a bug in other architecture. Architecture specific patches should only be appliaed when build the related architecture. A patch may fix a problem on one architecture however it could introduce a problem in another architecture. Limiting exposure limits any possible crosstalk between architectures.

If you have a configuation issue try adding the --dry-run option. This will run through all the configuration files and if any checks fail you will see this quickly rather than waiting for until the build fails a check.

Following features can be enabled/disabled via the command line for the RTEMS build sets:


Do not build a C++ compiler.


Attempt to build an Ada compiler. You need a native GNAT installed.


Attempt to build a Fortran compiler.


Attempt to build a C++ compiler.

--with-newlib-tls or --without-newlib-tls

Enable or disable the --enable-newlib-reent-thread-local Newlib configuration option. This option is enabled by default on the aarch64, arm, nios2, powerpc, riscv, and sparc targets. If this option is enabled, then each member of the Newlib struct _reent is replaced by a dedicated thread-local object. The thread-local objects are defined in translation units which use the corresponding object so that only objects used by the application are linked in.

The RSB provides build sets for some BSPs. These build sets will build:

  • Compiler, linker, debugger and RTEMS Tools.

  • RTEMS Kernel for the BSP

  • Optionally LibBSD if supported by the BSP.

  • Third party packages if supported by the BSP.

15.2.3. Patches

Packages being built by the RSB need patches from time to time and the RSB supports patching upstream packages. The patches are held in a seperate directory called patches relative to the configuration directory you are building. For example %{_topdir}/patches:%{_sbdir}/patches. Patches are declared in the configuration files in a similar manner to the package’s source so please refer to the %source documentation. Patches, like the source, are to be made publically available for configurations that live in the RSB package and are downloaded on demand.

If a package has a patch management tool it is recommended you reference the package’s patch management tools directly. If the RSB does not support the specific patch manage tool please contact the mailing list to see if support can be added.

Referenced patches should be placed in a location that is easy to access and download with a stable URL. We recommend attaching a patch to an RTEMS ticket in it’s bug reporting system or posting to a mailing list with online archives.

RTEMS’s former practice of placing patches in the RTEMS Tools Git repository has been stopped.

Patches are added to a component’s name and in the %prep: section the patches can be set up, meaning they are applied to source. The patches are applied in the order they are added. If there is a dependency make sure you order the patches correctly when you add them. You can add any number of patches and the RSB will handle them efficiently.

Patches can have options. These are added before the patch URL. If no options are provided the patch’s setup default options are used.

Patches can be declared in build set up files.

This examples shows how to declare a patch for gdb in the lm32 architecture:

%patch add <1> gdb <2> %{rtems_gdb_patches}/lm32/gdb-sim-lm32uart.diff <3>

Patches require a checksum to avoid a warning. The %hash directive can be used to add a checksum for a patch that is used to verify the patch:

%hash sha512 <1> gdb-sim-lm32uart.diff <2> 77d07087 ... e7db17fb <3>

The patches are applied when a patch setup command is issued in the %prep: section. All patches in the group are applied. To apply the GDB patch above use:

%patch setup <1> gdb <2> -p1 <3>

Architecture specific patches live in the architecture build set file isolating the patch to that specific architecture. If a patch is common to a tool it resides in the RTEMS tools configuration file. Do not place patches for tools in the source-builder/config template configuration files.

To test a patch simply copy it to your local patches directory. The RSB will see the patch is present and will not attempt to download it. Once you are happy with the patch submit it to the project and a core developer will review it and add it to the RTEMS Tools git repository. Testing a Newlib Patch

To test a local patch for newlib, you need to add the following two lines to the .cfg file in rsb/rtems/config/tools/ that is included by the bset you use:

%patch add newlib -p1 file://0001-Port-ndbm.patch <1>
%hash sha512 0001-Port-ndbm.patch 7d999ceeea4f3dc82e8e0aadc09d983a7a68b44470da8a3d61ab6fc558fdba6f2c2de3acc2f32c0b0b97fcc9ab799c27e87afe046544a69519881f947e7881d1 <2>