View source for Embedded Linux system basis

An embedded Linux system is very similar (when speaking about software) to a Desktop one, thanks to the power of the latest embedded microprocessor, like the ARM9 one.
It is composed of:
* a '''bootloader''', which is the first bits of code executed when the processor starts. It behaves like the BIOS+Grub combination on Desktop PCs.
* an operating system = the '''Linux kernel'''
* many programs and librairies organised in a filesystem = the '''rootfs'''

==The bootloader==
In our case our bootloader is U-Boot. It's main role is to initialize the hardware, load the Linux kernel and launch it with the correct parameters

==The kernel==
In our case Linux.

==The rootfs==
It is composed of:
* a C library
* basic utilities (in our case regrouped as one executable through [[Busybox]])
* additionnal librairies and tools

==Build system / toolchain==
To build all these tools, you need a "build system". We use Buildroot. 
# This system will build a gcc cross-toolchain that will allow to generate on your PC software that can be run on your APF.
# When this toolchain is ready it will compile the bootloader, the kernel and the tools of the rootfs
# Finally it will generate images of these 3 components that can be "flashed" on your APF