The GNU toolchain is a term used for a collection of programming tools under the GNU Project umbrella. This suite of tools is what is normally called a toolchain, and is used for the development of applications and operating systems. It plays an important role in the development of embedded systems and Linux systems, in particular.

The following projects are included in the GNU toolchain:

The projects included in the toolchain is described...

The first library that we'll discuss here is the glibc library, which is designed for performance, compliance of standards, and portability. It was developed by the Free Software Foundation for the GNU/Linux operating system and is still present today on all GNU/Linux host systems that are actively maintained. It was released under the GNU Lesser General Public License.

The glibc library was initially written by Roland McGrath in the 1980s and it continued to grow until the 1990s when the Linux kernel forked glibc, calling it Linux libc. It was maintained separately until January 1997 when the Free Software Foundation released glibc 2.0. The glibc 2.0 contained so many features that it did not make any sense to continue the development of Linux libc, so they discontinued their fork and returned to using glibc. There are changes that are made in Linux libc that were not merged into glibc because of problems with the authorship of the code.

The glibc library is...

When generating a toolchain, the first thing that needs to be done is the establishment of an ABI used to generate binaries. This means that the kernel needs to understand this ABI and, at the same time, all the binaries in the system need to be compiled with the same ABI.

When working with the GNU toolchain, a good source of gathering information and understanding the ways in which work is done with these tools is to consult the GNU coding standards. The coding standard's purposes are very simple: to make sure that the work with the GNU ecosystem is performed in a clean, easy, and consistent manner. This is a guideline that needs to be used by people interested in working with GNU tools to write reliable, solid, and portable software. The main focus of the GNU toolchain is represented by the C language, but the rules applied here are also very useful for any programming languages. The purpose of each rule is explained by making sure that the logic behind the...

As I have mentioned, the major advantage and available feature of the Yocto Project environment is represented by the fact that a Yocto Project build does not use the host available packages, but builds and uses its own packages. This is done to make sure that a change in the host environment does not influence its available packages and that builds are made to generate a custom Linux system. A toolchain is one of the components because almost all packages that are constituents of a Linux distribution need the usage of toolchain components.

The first step for the Yocto Project is to identify the exact sources and packages that will be combined to generate the toolchain that will be used by later built packages, such as U-Boot bootloader, kernel, BusyBox and others. In this book, the sources that will be discussed are the ones available inside the dizzy branch, the latest poky 12.0 version, and the Yocto Project version 1.7. The sources can be gathered using the...