This page describes the port of the u-boot bootloader to the Galaxy Nexus phone


There were a couple reasons to port u-boot to Galaxy Nexus


Compilation from source

Source code is in

There exist two branches of interest

To compile, you need to have the ARM cross-compiler. I recommend codesourcery 2010q1-188 because that’ s what I ‘m using and some users reported that newer compilers produce broken binaries.

There are two ways to use the u-boot. One is flashing it instead of the Samsung SBL bootloader. The other one is chainloading it from the SBL.

Flashing instead of SBL has the following advantages

There is a number of issues and therefore we do not recommend flashing it instead of SBL

By default, the chainloaded version is compiled. It is loaded (by the SBL) to the address 0x81808000.

If you want to build the SBL replacement version, edit the include/configs/omap4_tuna.h file and uncomment the #define TUNA_SPL_BUILD line. X-loader loads the bootloader to the address 0xa0208000.

export PATH=/home/alexander/handhelds/armv6/codesourcery/bin:$PATH
export ARCH=arm
export CROSS_COMPILE=arm-none-eabi-

make clean
make distclean

make ${U_BOARD}_config
make -j8 ${U_BOARD}
mkbootimg --kernel u-boot.bin --ramdisk /dev/null -o u-boot.aimg


Chainloaded Mode

You will need the root access to your device. You can take the prebuilt u-boot here. [gnex-uboot-chainloaded.img]

The u - boot has the support for android boot images.When flashed instead of the SBL, it boots the kernel off the “Boot” partition. When chainloaded, it looks for the kernel in /system/boot/vmlinux.uimg. Additionally, it first looks for the /system/boot/boot.scr.uimg so you can put custom commands there and override the kernel image.

It also supports booting custom images from /sdcard/boot/vmlinux.uimg and /sdcard/boot/boot.scr.uimg.

If you need larger images, I suggest that you use the tuna-fosdem-hacks branch, format the cache partition to ext2 and put the files to /cache/media/boot/.

push the files to your device via adb

adb push gnex-uboot-chainloaded.img /sdcard/ 
adb hell 

now, in the device shell, do the following:

su cat /dev/block/platform /omap/omap_hsmmc.0/by-name/boot > /sdcard /vmlinux.uimg mount - o remount, rw /system mkdir/system/boot cp /sdcard/vmlinux.uimg /system/boot/ cat /sdcard/gnex-uboot-chainloaded.img > /dev/block/platform /omap /omap_hsmmc.0/by-name/boot sync reboot

you can also use fastboot to flash u-boot.img instead of dd’ing it

fastboot flash:raw boot u-boot.img”

Replacing samsung bootloader

OMAP4 devices cannot be bricked completely because the CPU has a firmware loader in the OTP (one-time programmable) memory. When the device is powered, it tries booting from USB.

Make sure to have an old version of x-loader (PRIMEKK14) because newer ones have the security hole which allowed booting unsigned bootloaders fixed.

Take the x-loader here [gnex-xloader-working.img]

adb push gnex-xloader-working.img /sdcard/

The installation procedure is roughly the same, but use sbl partition. Also, install xloader by

cat /sdcard/gnex-xloader-working.img > /dev/block/platform/omap/omap_hsmmc.0/by-name/xloader

There exists a Samsung recovery tool which can unbrick the devices with corrupted xloader/SBL. You will need a computer running Windows XP.

Search the internet for the archive named “” which has md5 “ddbf07a1d36b044c40af5788a83b5395”. We cannot upload it here because of the unclear license status.

Making images

You can either use Android’ s mkbootimg to produce ANDROID !type images (not recommended) or u-boot’s mkimage (in the u-boot tools directory) to make boot images. Using ANDROID! format is discouraged because the loader code in the u-boot is buggy and may fail in some corner cases such as large images.

making a custom boot image

mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n linux -d zImage vmlinux.uimg

#alternatively, just do that when compiling linux

#do not forget to add mkimage to your PATH variable make uImage making a custom boot script

mkimage -A arm -O linux -T script -C none -a 0x84000000 -e 0x84000000 -n android -d boot.scr boot.scr.uimg

Booting Modes

The bootloader supports several boot modes. Each boot mode is indicated by the color of the LED and activated by a combination of hardware buttons. It also supports the Android “reboot to recovery” and “reboot to bootloader” features


A sample boot script for android

Make a boot.scr.uimg from it and push it to the correct location.

setenv bootargs “mem=1G vmalloc=768M omap_wdt.timer_margin=30 mms_ts.panel_id=18 no_console_suspend console=ttyFIQ0”;

setenv loaddaddr 0x82000000;

setenv devtype mmc;

setenv devnum 0;

setenv kernel_part 0xc;

setenv kernel_name /media/boot/vmlinux.uimg;

echo Load Address: ${loaddaddr};

echo cmdline:${bootargs};

if ext4load ${devtype} ${devnum}:${kernel_part} ${loaddaddr} ${kernel_name}; then

bootm ${loaddaddr};

exit 0\;

elif ext2load ${devtype} ${devnum}:${kernel_part} ${loaddaddr} ${kernel_name}; then

bootm ${loaddaddr};

exit 0;


echo failed to boot custom image;