Difference between revisions of "Embedded Linux system basis"
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| − | 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 | + | An embedded Linux system is very similar (when speaking about software) to a Desktop one, thanks to the power of the latest embedded microprocessor cores, like the ARM9™/Cortex™ ones. |
It is composed of: | 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. | * 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''' | * an operating system = the '''Linux kernel''' | ||
| − | * many programs and librairies | + | * many programs and librairies organized in a filesystem = the '''rootfs''' |
==The bootloader== | ==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 | + | In our case our bootloader is [http://www.denx.de/wiki/view/U-Boot U-Boot]. It's main role is to initialize the hardware, load the Linux kernel and launch it with the correct parameters |
==The kernel== | ==The kernel== | ||
| + | In our case [https://www.kernel.org/ Linux™]. | ||
==The rootfs== | ==The rootfs== | ||
It is composed of: | It is composed of: | ||
| − | * a C library | + | * a C library (mostly uClibc or glibc in our boards), |
| − | * basic utilities (in our case | + | * basic utilities (in our case regrouped as one executable through [[Busybox]]), |
| − | * | + | * additional libraries and tools, |
| + | |||
| + | ==Build system / toolchain== | ||
| + | To build all these tools, you need a "build system". We use [https://buildroot.org/ 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/OPOS module | ||
| + | |||
| + | |||
| + | ARM9 & Cortex are registered trademarks of [https://www.arm.com/ ARM Limited]. | ||
| + | |||
| + | Linux is a registered trademark of Linus Torvalds. | ||
Latest revision as of 08:31, 22 November 2016
An embedded Linux system is very similar (when speaking about software) to a Desktop one, thanks to the power of the latest embedded microprocessor cores, like the ARM9™/Cortex™ ones. 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 organized 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 (mostly uClibc or glibc in our boards),
- basic utilities (in our case regrouped as one executable through Busybox),
- additional libraries 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/OPOS module
ARM9 & Cortex are registered trademarks of ARM Limited.
Linux is a registered trademark of Linus Torvalds.
