The list of booting devices that the ROM code will search through for the Stage of bootloader (SPL) as well as loading the actual next stageīootloader code into memory and starting it Readies the device for next bootloader by checking boot sources for next.Such as stack setup, configuring the Watchdog Timer (see TRM for details)Īs well as the PLL and system clocks configuration Configuration of the device and initialization of primary peripherals.To get an understanding of what exactly the ROM code is doing. The ROM bootloader code is hardcoded into theĭevice and cannot be changed by the user. The first block of code that is automatically run on device start-up orĪfter power-on reset (POR). The first stage bootloader is housed in ROM on the device. There are four distinct bootloader stages:
U BOOT CONSOLE FULL
Systematically unlock the full functionality of the device so that allĬomplexities of the device are available to the kernel. Of RAM, multiple bootloader stages are needed. This section will review the four bootloader software stages that mustīe run before the kernel can be booted and run on the device.Īpplication processors such as the the AM335x are complex pieces of hardware,īut have limited internal RAM (e.g., 128KB).
Pointing a program counter to the kernel location and letting the processor Will leverage other files under include/configs, as seen by #includeīooting the Linux kernel on an embedded platform is not as simple as simply And please note that the main config file To find these read the ‘boards.cfg’ file and look for Here as the community has additional build targets that are not Note that not all possible build targets for a given platform are listed $ make CROSS_COMPILE=arm-linux-gnueabihf- O=am335x_evm $ make CROSS_COMPILE=arm-linux-gnueabihf- O=am335x_evm am335x_evm_defconfig # Use 'am335x_evm' and 'AM335x GP EVM' in this example Use the following table to determine what defconfig to use to configure However first configure the build for the board you are working with. Building of both u-boot and SPL is done at the same time.
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