#Buildroot iramdisk how to#
#Buildroot iramdisk serial#
#Buildroot iramdisk update#
#Buildroot iramdisk free#

Note: In the meantime, the OP-TEE build project 6 also started using Buildroot for building, but at the time of this writing, RPi3 still uses gen-rootfs. You can follow the tutorial below to achieve this. We replaced the above mentioned default rootfs with the one generated by Buildroot and the kernel too OP-TEE, U-Boot images and configuration are from the OP-TEE build output. The main product of Buildroot is the root filesystem image. Here is a more in-depth comparison of the two projects.

#Buildroot iramdisk free#

Also, it is free of corporate management and has an open community. By default it generates small images in a minimalist approach. It re-uses existing technologies, such as kconfig and make. We chose Buildroot, because it is simpler to use and understand than Yocto and has a strong focus on simplicity. Both are Free Software: Buildroot is released under GNU GPL version 2 (or later), Yocto is a mix of MIT and GPLv2. Both have great documentation and online training courses.

Both are very actively developed and maintained projects, and they are widely used in the industry by companies like Intel, Juniper, Xilinx, Texas Instruments etc. Everything is compiled from scratch using cross compilation. These build systems provide the rootfs, toolchains, kernel, bootloader and a great number of installable packages. With these solutions one can build a completely customizable embedded Linux system. This is when Buildroot and Yocto Project comes in the picture. One might prefer to use a traditional Linux distribution like Raspbian, but in those mainline distributions OP-TEE support is missing or incomplete unfortunately. Adding Linux packages this way is not practical, as updating the packages and OP-TEE trusted applications and delivering those updates becomes cumbersome after some time. This is usable for testing OP-TEE and its functionalities, but for more complex applications, greater customizability is needed. When using OP-TEE on the Raspberry Pi 3 the default root file system (rootfs) is generated with a simple initramfs build script: gen-rootfs. This one describes how you can build your own custom Linux system (with OP-TEE) using the Buildroot environment.

#Buildroot iramdisk how to#

The first post explained how to build and install the default OP-TEE implementation for the Raspberry Pi 3.

#Buildroot iramdisk update#

Besides the ones I showed, one can also perform U-Boot update or write sophisticated scripts to decide how to perform the boot process, which is especially handy during development.This blog post, written by Szilárd Dömötör, is the second post in a series of blog posts on transforming the Raspberry Pi into a security enhanced IoT platform. To sum up, U-Boot gives a lot of options to boot the RPi. Scripts themselves can also be downloaded via tftp: usb start $ mkimage -A arm -O linux -T script -C none -n update.scr -d update.scr $ mkimage -A arm -O linux -T script -C none -n boot.scr -d boot.scr In order to boot Linux, the following needs to be done: mmc dev 0įatload mmc 0:1 $ Interrupting the autoboot will give access to command line interface. After that it will either search for a start script or try to setup network interfaces and boot from network. U-Boot waits 3 seconds for the user to interrupt the autoboot. ** Unable to read 'uboot.env' from mmc0:1 **

#Buildroot iramdisk serial#

Powering up the RPi with serial console attached gives this result: U-Boot 2016.01 (14:55:52 +0200)

Also, in config.txt, which is also on the boot partition, change: kernel=zImage Now the SD card needs to be mounted and the U-Boot binary should be copied to boot partition. After exiting config, run: $ make allĪfter compiling, Buildroot puts u-boot.bin in output/images. U-Boot board name shows up, and needs to be set to rpi.

Use Buildroot to compile U-Boot: $ make nconfig I will use U-Boot, and show how to step by step migrate to a more customizable bootloader.Ĭheck how to start with Buildroot and Raspberry Pi first.

Although, there is a possibility to have the root file system booted from network with the stock firmware (actually the kernel allows that), lets look at an interesting alternative. The GPU executes bootcode.bin, the second bootloader, which in the end runs the kernel. The first one resides in built-in ROM and is responsible for starting the GPU. Raspberry Pi has a fairly complicated boot process with two bootloaders.