https://wiki.st.com/stm32mpu/wiki/How_to_cross-compile_with_the_Distribution_Package 1)Go to the build directory
cd /home/sharan/STM32MPU/Distribution-Package/build-openstlinuxweston-stm32mp15-disco/tmp-glibc/work-shared/stm32mp15-disco/uboot-source/board/st/stm32mp1/
2)Start to work with u-boot
devtool modify u-boot-stm32mp
3)Edit the ./board/st/stm32mp1/stm32mp1.c source file
Add a log information in the checkboard function
4)Cross-compile the U-Boot
devtool build u-boot-stm32mp
bitbake u-boot-stm32mp -c deploy
5)if u want to modify again and the first modification devtool reset u-boot-stm32mp # Wipe previous work if needed and repeat step 2 to 4
6)U-Boot are put on FIP image via TF-a fip generation
bitbake fip-stm32mp
7)Go to the directory in which the compilation results are stored
cd <build dir>/tmp-glibc/deploy/images/<machine name>/fip
8)Reboot the board, and hit any key to stop in the U-boot shell
reboot
[...]
Hit any key to stop autoboot: 0
STM32MP>
9)Connect a USB cable between the host machine and the board via the USB OTG ports
In the U-Boot shell, call the USB mass storage function
STM32MP> ums 0 mmc 0
10)Copy the binary (fip-<board name>-optee-<storage>.bin) to the dedicated partition
dd if=fip-<board name>-optee-<storage>.bin of=/dev/sdc5 bs=1M conv=fdatasync
(here fip-stm32mp157f-dk2-optee.bin for stm32mp15-disco machine)
11)Reset the U-Boot shell
STM32MP> reset
Have a look at the new U-Boot log information when the board reboots
[...]
U-Boot <U-Boot version>
CPU: STM32MP157FAC Rev.Z
Model: STMicroelectronics STM32MP157F-DK2 Discovery Board
Board: stm32mp1 in trusted mode (st,stm32mp157f-dk2)
U-Boot simple example
[...]
