Barebox as alternative to uBoot

Maybe usefull for bringing up hardware and bootup linux or whatever:

https://www.barebox.org/

This is looking promising, especially because U-Boot has dropped the support for the i.MX25. Barebox seems to have devicetree-support for the i.MX25, but the dtsi-file is very short. So this needs more investigation but could be the bootloader for the final system.

Repo/Branch: https://github.com/OpenMixerProject/barebox/tree/openx32

load barebox using u-boot, to check the basics
if this works, then replace u-boot with barebox
if this works, get the rest working (mmc read, ...)
get MMU working -> barebox should be faster with MMU
boot linux
get USB working -> to enable others to boot the full stack using imx-usb-loader and a prepared USB drive without the need to modify their console
(optional) implement a driver to get up/down/left/right key working (for menutree)

current state:

barebox builds as u-boot bootable image in kernel format (using bootz command)
u-boot loads barebox ("Starting Kernel ..."), but nothing happens after this ;-)
need to sort out the serial3 port

🚀

Upload via imx-usb-loader works and the lamp turns on via DCD-Table (https://github.com/xn--nding-jua/OpenX32/wiki/Booting)

Next step is to get barebox booting without chainloading via u-boot

successfully bootet barebox standalone on the X32 🚀

Congratulations! How many changes did you make on the barebox-repository. Is it necessary to keep the individual fork or can we take the regular barebox-repository with minimum changes like on U-Boot?

It's just the serial downloader which works, currently I debug the load from sd card.

I would keep the fork and try to push it upstream some time.

bootet barebox, mounted sd card, tried to boot the linux kernel

Current state:

sd card can be mount
usb is somewhat working
framebuffer driver is loaded

Error: Cannot request SDRAM region for stack
imx-esdhc 53fb4000.mmc@53fb4000.of: registered as mmc0
mmc0: detected SD card version 2.0
mmc0: registered mmc0
gpiolib: _gpio_request: gpio-120 (mculed) status -16
gpiolib: _gpio_request: gpio-26 (lamp) status -16
gpiolib: _gpio_request: gpio-124 (reset_surface) status -16
imx-di-rtc 53ffc000.dryice@53ffc000.of: Unlocked unit detected
imxfb imxfb: i.MX Framebuffer driver
fb0: framebuffer console 100x30 activated
fbconsole: registered as fbconsole0-1
fb1: framebuffer console 100x30 activated
fbconsole: registered as fbconsole1-1
malloc space: 0x8de00000 -> 0x8fdfffff (size 32 MiB)
environment load /dev/env0: No such file or directory
Maybe you have to create the partition.

Hit any to stop autoboot:    1
boot: No such file or directory
barebox:/

Cool. Would be great to have a bootmenu to select between OpenX32 and the original Firmware. Should be possible to create a fifth Partition on a larger SD Card. Or we could place our barebox at 0x400 of the SD Card and move the DCP Loader to a later position.

Your progress looks promising 👍

First boot from sd card worked!

The trick was to use just allowed ranges in the DCD-Table, as mentioned in the reference manual ;-)
Setting the GPIO-PINs was not allowed.

normal colors and no more screen artifacts in barebox
splash logos can be shown

mmu works, barebox is way faster :-)
barebox loads the kernel and device tree, but nothing happens

Hit m for menu or any to stop autoboot:    1
barebox@Behringer X32 - OpenX32:/ boot mmc
Booting entry 'mmc'

Loading ARM Linux zImage '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/sd/zImage'
request region(0x82158000:0x82803327): success flags=0x200
Loading devicetree from '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/sd/imx25-pdk.dtb'
request region(0x82904000:0x82909c85): success flags=0x200
commandline: console=ttymxc4,115200 console=tty0 video=imxfb:800x480  
exitcall-> nv_exit+0x0/0x38
exitcall-> devices_shutdown+0x0/0xa8
    remove-> fat0
    remove-> 53ff4400.usb@53ff4400.of
    remove-> 53ff4000.usb@53ff4000.of
    remove-> devfs0
    remove-> ramfs0
exitcall-> umsmod_exit+0x0/0x10
exitcall-> arch_shutdown+0x0/0x20

I think the memory initialisation is not right. The DTS file defines 0x80000000 to 0x84000000 as RAM (==64MB), but barebox add two more regions, one from 0x90000000 :-/

I think it's time for a break ⏸️ to rethink and get new brain power...

got it! Linux is booting from barebox 🚀

the trick was to disable the second (not used) sdram controller via DCD table:

# Disable ESDCTL1
wm 32 0xB8001008 0x0

Next step is to include Barebox into the DCP-Loader image

Next step is to include Barebox into the DCP-Loader image

That's harder than expected 😑 I can not get barebox to load from the DCP-Loader

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Barebox as alternative to uBoot #19

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Barebox as alternative to uBoot #19

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xn--nding-jua commented on Aug 2, 2025

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