2.4. Install the Tool Suite

You have chosen an installation prefix, the BSP to build, the tool’s architecure and prepared the source for the RSB in the previous sections. We have chosen $HOME/quick-start/rtems/5 as the installation prefix, the erc32 BSP and the SPARC architecture name of sparc-rtems5, and unpacked the RSB source in $HOME/quick-start/src.

The tool suite for RTEMS and the RTEMS sources are tightly coupled. For example, do not use a RTEMS version 5 tool suite with RTEMS version 4.11 sources and vice versa.

Build and install the tool suite:

cd $HOME/quick-start/src/rsb/rtems
../source-builder/sb-set-builder --prefix=$HOME/quick-start/rtems/5 5/rtems-sparc

This command should output something like this (omitted lines are denoted by …). The build host appears as part of the name of the package being built. The name you see may vary depending on the host you are using:

RTEMS Source Builder - Set Builder, 5.1.0
Build Set: 5/rtems-sparc
...
config: tools/rtems-binutils-2.34.cfg
package: sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1
building: sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1
sizes: sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1: 305.866MB (installed: 29.966MB)
cleaning: sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1
reporting: tools/rtems-binutils-2.34.cfg -> sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1.txt
reporting: tools/rtems-binutils-2.34.cfg -> sparc-rtems5-binutils-2.34-x86_64-freebsd12.1-1.xml
config: tools/rtems-gcc-7.5.0-newlib-fbaa096.cfg
package: sparc-rtems5-gcc-7.5.0-newlib-fbaa096-x86_64-freebsd12.1-1
building: sparc-rtems5-gcc-7.5.0-newlib-fbaa096-x86_64-freebsd12.1-1
....
Build Sizes: usage: 5.684GB total: 1.112GB (sources: 143.803MB, patches: 21.348KB, installed 995.188MB)
Build Set: Time 0:21:35.626294

Once the build has successfully completed you can check if the cross C compiler works with the following command:

$HOME/quick-start/rtems/5/bin/sparc-rtems5-gcc --version

This command should output something like below. The version informtion helps you to identify the exact sources used to build the cross compiler of your RTEMS tool suite. In the output you see the version of RTEMS or the hash from the RSB repository if you are building using a Git repository clone. The Newlib hash is the version of Newlib in the RTEMS’s github sourceware-mirror-newlib-cygwin repository. The sources and patches directories created by the RSB contain all the source code used.

sparc-rtems5-gcc (GCC) 7.5.0 20191114 (RTEMS 5, RSB 5.1.0, Newlib fbaa096)
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Add --verbose to the GCC command for the the verbose version details.

2.4.1. Need for RTEMS-Specific Cross-Compiler

New users are often confused as to why they cannot use their distribution’s cross-compiler for their target on RTEMS, e.g., the riscv64-linux-gnu or the arm-none-eabi-gcc. Below mentioned are some of the reasons for using the RTEMS cross-compiler.

Correct configuration of Newlib
Newlib is a C standard library implementation intended for use on embedded systems. Most of the POSIX and libc support for RTEMS is derived from Newlib. The RTEMS cross-compiler configures Newlib correctly for RTEMS.
Threading in GCC support libraries
Several threading packages in GCC such as Go threads (libgo), OpenMP (libgomp), and OpenACC need to be customized according to RTEMS. This is done by the RTEMS specific cross-compiler.
Provide preprocessor define __rtems__
The __rtems__ preprocessor define is used to provide conditional code compilation in source files that are shared with other projects e.g. in Newlib or imported code from FreeBSD.
Multilib variants to match the BSP
RTEMS configures GCC to create separate runtime libraries for each supported instruction set, floating point unit, vector unit, word size (e.g. 32-bit and 64-bit), endianness, ABI, processor errata workarounds, and so on in the architecture. These libraries are termed as Multilib variants. Multilib variants to match the BSP are set by selecting a specific set of machine options using the RTEMS cross-compiler.