Boot Loaders
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8/27/2008
The boot loader is a utility that is an integral part of the OEM device development process. In some cases, it is also included in the final OEM product. The general purpose of the boot loader is to place the run-time image into memory, and then jump to the OS startup routine. The boot loader can obtain the run-time image in a number of different ways, including loading it over a cabled connection, such as Ethernet, a universal serial bus (USB), or serial connection. The boot loader also loads the OS from a local storage device, such as Compact Flash, or a hard disk. The boot loader might store the run-time image in RAM or in nonvolatile storage, such as flash memory, electrically erasable programmable read only memory (EEPROM), or some other storage device for later use.
Using the boot loader during the board support package (BSP) development process saves time. You can quickly download a new run-time image to a target device using a boot loader rather than manually transferring the run-time image to a target device using a flash memory programmer or IEEE 1149.1-compliant test access port and boundary-scanning technology.
In many final OEM products, the boot loader is removed from the product and the system reset process bootstraps the run-time image, which is stored on the device. However, hardware platforms that do not efficiently support this ability, such as x86 platforms, or hardware platforms that need to perform pre-boot tasks, such as run-time image updates, might include the boot loader in the final product.
For more information on the entire development process for a boot loader, see How to Develop a Boot Loader.
Although each boot loader differs in the tasks it carries out and the way it performs them, the most common boot loader downloads the run-time image over Ethernet into RAM on a target device. The following topics describe this common boot loader and the basic infrastructure and concepts that apply to all boot loaders. They also describe the libraries and functions you can use to develop a boot loader.
- Recommended Boot Loader Functionality
- Hardware Considerations for the Boot Loader
- Modes for Booting the OS
- Ethernet Boot Loader
- Specialized Boot Loaders
- Boot Loader Support Libraries
See Also
Concepts
Board Support Package Overview
OEM Adaptation Layer