arm嵌入式bootloader启动过程详解（国外英文资料）.docVIP

arm嵌入式bootloader启动过程详解（国外英文资料） ARM embedded system Bootloader Introduction: For PC, the boot after the initialization of the processor configuration, hardware initialization operation is performed by the BIOS (Basic Input/Output System), but for embedded System, for the sake of economy, the price is generally not configure the BIOS, so we must finish the work to write program, which is needed to boot program. In embedded systems, usually does not like the BIOS firmware program, started to complete initialization of this code is called the Bootloader program, so the load of the whole system to start the task is accomplished by the Bootloader. Say simply, through this program, you can initialize the hardware equipment, establish a memory map (or no memory mapping functions such as S3C44B0 CPU), and the system hardware and software environment is set in a suitable condition, so as to eventually invoke the operating system kernel, ready to run an application program the right environment. Bootloader relies on the actual hardware and application environments, so it is very difficult to build a generic, standard Bootloader for embedded systems. Bootloader also depends on the configuration of embedded board level equipment, that is to say, for two different embedded motherboard, even though they are based on the same CPU and build, to run on a board Bootloader program can also run on another board, usually need to modify the Bootloader source program. Second. Start the process After the system is reset, almost all the cpus are taken from the reset address. For example, the CPU based on the ARM7TDMI kernel usually takes its first instruction from address 0in the reset. And with microprocessor as the core of the embedded systems usually have some type of solid-state storage device block (such as EEPROM, FLASH, etc.) are mapped to the preset address. Therefore, after the system is recharged, the processor will first execute the program stored in the reset address.