The bootloader U-Boot

From IGEP - ISEE Wiki

Jump to: navigation, search

Overview

This page is meant to be a starting point for people to learn build a u-boot image and show to people the current status of different u-boot versions for IGEP Processor Boards.

What is U-Boot?

Das U-Boot (Universal Bootloader) is an open source, primary boot loader used in embedded devices. Its primary purpose in the shipping system is to load some operating system.

That means that U-Boot is necessary to perform a certain task, but it's nothing you want to throw any significant resources at. Typically U-Boot is stored in relatively small NOR flash memory, which is expensive compared to the much larger NAND devices often used to store the operating system and the application.


Necessary package

In order to compile the u-boot it is necessary to set up the Cross Compiler correctly. In this post it is detailed how to set up correctly the Cross Compiler (and the desired version).

Information.jpg The following steps has been tested using Ubuntu 16.04 and the 4.9 version of the arm-linux-gnueabihf compiler

In order to install the Compiler we can use this command:

sudo apt install gcc-arm-linux-gnueabihf

Download U-Boot Source

 First of all, will be a distintion between NXP-processors products and ARM-processors products. Because there are different kinds of U-Boot depending of each processor.

Commercial Name U-Boot Series
IGEPv2 DM3730 U-boot-ARM
IGEP COM MODULE DM3730/AM3703 U-boot-ARM 
IGEP COM AQUILA AM335x U-boot-ARM 
IGEPv5 OMAP5432 U-boot-ARM 
IGEP SMARC AM335x U-boot-ARM 
IGEP SMARC iMX6  U-boot-Freescale-NXP
  • Once we know which U-Boot have we will clone the corresponding git repository.


U-Boot ARM Series

If we have an ARM series we will follow this table to get our source of U-Boot
Downloading binary files/U-Boot Source
Clone the u-boot repository

Clone the u-boot repository using git address:

git clone git@git.isee.biz:arm-boot/u-boot-arm.git 

or

 git clone https://git.isee.biz/arm-boot/u-boot-arm.git

Checkout u-boot repository

Go to the u-boot-arm directory and checkout the isee_v2017.03 as:

cd u-boot-arm

git checkout remotes/origin/isee_v2017.03 -b isee_v2017.03 


U-Boot Freescale-NXP  Serie

If we have an Freescale-NXP series we will follow this table to get our source of U-Boot
Downloading binary files/U-Boot Source
Clone the u-boot repository

Clone the u-boot repository using git address:

git clone git@git.isee.biz:arm-boot/u-boot-imx.git

or

 git clone https://git.isee.biz/arm-boot/u-boot-imx.git

Checkout u-boot repository

Go to the u-boot-imx directory and checkout the isee_imx_v2017.03.y as:

cd u-boot-imx

git checkout remotes/origin/isee_imx_v2017.03_4.9.11_1.0.0_ga -b isee_imx_v2017.03_4.9.11_1.0.0_ga 

Prepare your U-BOOT

Once we have downloaded the U-Boot source. We will execute the file called defconfig (default configuration) that it variates in function of each model.

In order to load the default configuration of the target board, we have to write the following command:

 make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- [your_defconfig]
  • In the following table it can be found the name of each default configuration associated to each IGEP PROCESSORS BOARDS:


Module Defconfig Example
IGEPv2 DM3730 igep0020_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- igep0020_defconfig
IGEP COM MODULE DM3730/AM3703 igep0030_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- igep0030_defconfig
IGEP COM AQUILA AM335x

am335x_igep0033_defconfig

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- am335x_igep0033_defconfig
IGEPv5 OMAP5432   make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-
IGEP SMARC AM335x am335x_igep0034_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- am335x_igep0034_defconfig
IGEP SMARC iMX6 Solo/Dual Lite igep0046_imx6dl_2G_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- igep0046_imx6dl_2G_defconfig
IGEP SMARC iMX6 Dual/ Quad igep0046_imx6q_2G_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- igep0046_imx6q_2G_defconfig
IGEP SMARC iMX6 Ultra-Lite / Ultra Ultra-Lite igep0146_imx6ul_512M_defconfig make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- igep0146_imx6ul_512M_defconfig

Build your U-BOOT

After running the defconfig. You can build the U-Boot by executing this command:

  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

Once the compile process has sucesfully finished, we will find the resulting files inside the u-boot root folder. Depending on the processor the generated files will be different:

  • The result for ARM processor based board will be a MLO and u-boot.img.
  • The result for Freescale-NXP processor based will be a u-boot.imx.


Finally we can copy this files in a boot device, for example, a microSD Memory Card. It is explained in the following post.

Information.jpg In case of the Freescale-NXP Porcessor Boards, it is not possible to copy directly the u-boot.imx file. It is necessary to copy in the first blocks of the boot device using the dd command. It is explained in the following post How to prepare a bootable MicroSD Card.


What next...

After build u-boot you have to download and compile kernel