What is SPL in U-Boot?

What is SPL in U-Boot?

So this first-stage bootloader is U-Boot SPL; and second-stage bootloader is regular U-Boot (or U-Boot proper). To be clear: SPL stands for Secondary Program Loader. Which means that ROM code is the first thing that loads (and executes) other program, and SPL is the second thing that loads (and executes) other program.

How do you customize U-Boot?

To summarize, you need to configure U-Boot for your with the following steps:

1. Add your board device tree: arch/arm/dts/.
2. Create your own board support directory: board//.
3. Add TARGET_ _ in Kconfig.
4. Create your board defconfig: defconfig/_defconfig.

What is SPL MLO?

“MLO” is the second-stage bootloader. The second-stage bootloader can apparently be one of either the X-loader or SPL. This bootloader apparently also just reads the first partition of the SD card, and loads a file called “u-boot. bin”, and executes it.

What is a U-Boot file?

U-Boot searches for an extlinux.conf configuration file for each bootable device. This file defines the kernel configuration to be used with bootm command: bootargs. files to start the OS: kernel (uImage) + device tree + ramdisk files (optional)

What is SPL TPL?

program loader (TPL) to enable a loader stub loaded by the code from the. SPL. It loads the final uboot image into DDR, then jump to it to begin. execution.

What is SPL in Linux?

spl (short for set priority level, after the PDP-11 assembler instruction of the same name) is the name for a collection of Unix kernel routines or macros used to change the interrupt priority level. This was historically needed to synchronize critical sections of kernel code that shouldn’t be interrupted.

How do you build a yocto U-boot?

1. 1 Toolchain installation for out of Yocto builds. To install the toolchain, follow Yocto Toolchain installation.
2. 2 Build U-Boot out of Yocto tree.
3. 3 Install the built U-Boot on an SD card.
4. 4 Update your U-Boot out of Yocto tree.

What is Defconfig?

defconfig. Generates a new kernel configuration with the default answer being used for all options. The default values are taken from a file located in the arch/$ARCH/defconfig file, where $ARCH refers to the specific architecture for which the kernel is being built.

Why U-Boot is required?

U-Boot boots an operating system by reading the kernel and any other required data (e.g. device tree or ramdisk image) into memory, and then executing the kernel with the appropriate arguments. U-Boot’s commands are actually generalized commands which can be used to read or write any arbitrary data.

How do you boot a load kernel?

The process of Uboot booting the kernel is to determine how to start the kernel by reading the bootcmd in the environment variable env. For example, uboot wants to read the kernel partition from the nand flash to the memory address 0x30007FC0 and start the kernel. You can use the following command: bootm 0x30007FC0.

Where is the U-boot image in the SPL?

The SPL loads the “full U-boot” image into memory, and runs it. The image resides in the 0xa2 partition, immediately after the SPL’s boot images (details below). U-boot launches, counts down for autoboot, and executes its default boot command (unless a key is pressed on the console, allowing an alternative boot through the shell).

Is the U-Boot preloader based on the SPL?

The Preloader is based on the SPL (Secondary Program Loader), which is a component of U-Boot, the open source bootloader. The following figure presents an overview of how the Preloader is generated, by using the tools provided with SoC EDS. See Generating and Compiling the Preloader for detailed steps on how to generate and compile the Preloader.

Is the uBoot image in the 0xA2 partition?

The 0xa2 partition is expected to contain raw boot images of the preloader, as explained below. Since there’s a 60 kB limit on this stage, the full U-boot loader can’t fit. Rather, the SPL (”Secondary Program Loader”) component of U-boot is loaded into the processor. The U-boot SPL, which functions as the preloader,…

Do you need SPL for U-Boot Dragonboard?

But for Dragonboard, SPL is not needed as the U-Boot finds its place in third stage of the booting process and by the time ample amount of external RAM and Flash is available for it to use. Below, is the booting process involved in Dragonboard410c for U-Boot: