Android UUU IMX8

Booting from USB using UUU (Universal Update Utility)

Introduction

UUU (Universal Update Utility) is an open source utility by NXP that allows downloading and executing code on i.MX SoCs through the Serial Download Protocol (SDP).
It is the next generation of NXP's MFGTOOL used to load SPL and U-Boot via the USB OTG port and optionally program the internal storage of the SOM.
For more details please visit https://github.com/NXPmicro/mfgtools

Note:
All Variscite SOMs are shipped with U-Boot pre-programmed on the internal storage.
In addition, all Variscite carrier boards have an SD card slot, and even in the unlikely event of the U-Boot being erased from the internal storage, the SOM can always be booted from an SD card (like our recovery SD card, for example).
So, generally, this utility is not needed, however, it is yet another option that can be used to boot (and optionally program) the Variscite SOMs, for anyone who is interested.

Step by step usage instructions

Download and build uuu:

$ sudo apt-get install libusb-1.0-0-dev libzip-dev libbz2-dev pkg-config cmake
$ cd ~
$ git clone https://github.com/NXPmicro/mfgtools.git
$ cd mfgtools
$ cmake .
$ make

Build U-Boot:

• Build U-Boot using the defconfig for SD card/eMMC. You can follow the "Build U-Boot from source code" instructions here.
  
• Copy the U-Boot image to the uuu directory:

$ cp ~/mfgtools/uuu/uuu ~/var_imx-p9.0.0_1.0.0-ga/android_buildout/target/product/dart_mx8mm

Boot the board into serial download mode:

• Set the board boot mode to SD card, while not having an actual card inserted in its slot.
  

Alternatively, set the board boot mode to eMMC/NAND flash, when the eMMC/NAND flash does not contain a bootloader.
Connect the board to your host PC via the USB OTG port, and power on the board.
The board should be recognized on the host as a "NXP Semiconductors SE Blank M850" (or something similar).

Note:
If your board only has a regular USB type-A connector and doesn't have a USB Micro-AB or Type-C receptacle, you can use a "male USB type-A to male USB type-A" cable.

Run uuu to load U-Boot on the board:

 $ cd ~/mfgtools/uuu
 $ sudo ./uuu ./spl_boot.lst

The board should now run U-Boot.
You can see its output on the console via the debug port, as always.

Note:
The default boot command when booting from USB is bootcmd_mfg - it is defined by default in include/configs/imx_env.h in the U-Boot source code, as part of the the board's default environment.
It can be redefined or made empty.

Flash Rootfs and Bootloader to eMMC

Once you see u-boot being booted on the serial terminal, hit enter to stop booting via fastboot. Run below command at u-boot prompt

=>ums  mmc 

This will expose the entire eMMC to host PC, and then you can flash the bootloader and rootfs and kernel.