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diff --git a/docs/manual/introduction.txt b/docs/manual/introduction.txt new file mode 100644 index 000000000..476ce257b --- /dev/null +++ b/docs/manual/introduction.txt @@ -0,0 +1,69 @@ +About Buildroot +=============== + +Buildroot is a set of Makefiles and patches that allows you to easily +generate a cross-compilation toolchain, a root filesystem and a Linux +kernel image for your target. Buildroot can be used for one, two or +all of these options, independently. + +Buildroot is useful mainly for people working with embedded systems. +Embedded systems often use processors that are not the regular x86 +processors everyone is used to having in his PC. They can be PowerPC +processors, MIPS processors, ARM processors, etc. + +A compilation toolchain is the set of tools that allows you to compile +code for your system. It consists of a compiler (in our case, +gcc+), +binary utils like assembler and linker (in our case, +binutils+) and a +C standard library (for example +http://www.gnu.org/software/libc/libc.html[GNU Libc], +http://www.uclibc.org/[uClibc] or +http://www.fefe.de/dietlibc/[dietlibc]). The system installed on your +development station certainly already has a compilation toolchain that +you can use to compile an application that runs on your system. If +you're using a PC, your compilation toolchain runs on an x86 processor +and generates code for an x86 processor. Under most Linux systems, the +compilation toolchain uses the GNU libc (glibc) as the C standard +library. This compilation toolchain is called the "host compilation +toolchain". The machine on which it is running, and on which you're +working, is called the "host system". The compilation toolchain is +provided by your distribution, and Buildroot has nothing to do with it +(other than using it to build a cross-compilation toolchain and other +tools that are run on the development host). + +As said above, the compilation toolchain that comes with your system +runs on and generates code for the processor in your host system. As +your embedded system has a different processor, you need a +cross-compilation toolchain - a compilation toolchain that runs on +your host system but generates code for your target system (and target +processor). For example, if your host system uses x86 and your target +system uses ARM, the regular compilation toolchain on your host runs on +x86 and generates code for x86, while the cross-compilation toolchain +runs on x86 and generates code for ARM. + +Even if your embedded system uses an x86 processor, you might be +interested in Buildroot for two reasons: + +* The compilation toolchain on your host certainly uses the GNU Libc + which is a complete but huge C standard library. Instead of using + GNU Libc on your target system, you can use uClibc which is a tiny C + standard library. If you want to use this C library, then you need a + compilation toolchain to generate binaries linked with it. Buildroot + can do that for you. + +* Buildroot automates the building of a root filesystem with all + needed tools like busybox. That makes it much easier than doing it + by hand. + +You might wonder why such a tool is needed when you can compile +gcc+, ++binutils+, +uClibc+ and all the other tools by hand. Of course doing +so is possible but, dealing with all of the configure options and +problems of every +gcc+ or +binutils+ version is very time-consuming +and uninteresting. Buildroot automates this process through the use +of Makefiles and has a collection of patches for each +gcc+ and ++binutils+ version to make them work on most architectures. + +Moreover, Buildroot provides an infrastructure for reproducing the +build process of your kernel, cross-toolchain, and embedded root +filesystem. Being able to reproduce the build process will be useful +when a component needs to be patched or updated or when another person +is supposed to take over the project. |