This article explains how to configure U-Boot to support Fastboot mode.
1. Fastboot[edit | edit source]
Fastboot is a protocol that was originally created for Android™ and is primarily used to modify the flash filesystem via a USB connection from a host computer, see U-Boot Documentation android/fastboot.rst for details.
2. Configure U-Boot to support Fastboot mode[edit | edit source]
Fastboot is supported in U-Boot but it is not necessarily enabled by default with configuration symbols defined in fastboot Kconfig file .
A U-Boot binary, and so a fip, can support only one mass storage device for Fastboot, defined in the used defconfig file.
For instance, if a U-Boot is configured to support Fastboot on eMMC, it cannot be used to program the SD card with Fastboot.
U-Boot configuration must be done according to the mass storage boot device, for STMicroelectronics boards we have:
- SD card is on mmc0.
- eMMC is on mmc1.
Refer to STM32CubeProgrammer flashlayout for more information.
To enable Fastboot or to modify the Fastboot configuration, the U-Boot configuration must be modified. This can be done with the SDK.
[edit | edit source]
U-Boot configuration for Fastboot can be done by using make menuconfig in the U-Boot source code.
Follow these steps to enable Fastboot support on SD card on STM32MP157F-EV1 
:
- Identify the mmc device number. Information can be seen here.
For the STM32MP157F-EV1 Evaluation board, SD card is on mmc0.
- Generate the configuration for the board:
make stm32mp15_defconfig
- Configure Fastboot
make menuconfig
For mmc0 (SD card)
Device Drivers --->
Fastboot support --->
[*] Enable USB fastboot gadget
(0xC0000000) Define FASTBOOT buffer address
(0x02000000) Define FASTBOOT buffer size
[*] Enable FASTBOOT FLASH command
(0) Define FASTBOOT MMC FLASH default device
[ ] Enable EMMC_BOOT flash/erase
[ ] Enable eMMC userdata partition flash/erase
[*] Enable the 'oem format' command
[ ] Enable the 'oem partconf' command
[ ] Enable the 'oem bootbus' command
For mmc1 (eMMC)
Device Drivers --->
Fastboot support --->
[*] Enable USB fastboot gadget
(0xC0000000) Define FASTBOOT buffer address
(0x02000000) Define FASTBOOT buffer size
[*] Enable FASTBOOT FLASH command
(1) Define FASTBOOT MMC FLASH default device
[*] Enable EMMC_BOOT flash/erase
(mmc1boot0) Target name for updating EMMC_BOOT1
(mmc1boot1) Target name for updating EMMC_BOOT2
[*] Enable eMMC userdata partition flash/erase
(mmc1) Target name for updating EMMC_USER
[*] Enable the 'oem format' command
[*] Enable the 'oem partconf' command
[*] Enable the 'oem bootbus' command
- Build u-boot
make DEVICE_TREE=stm32mp157f-ev1 all
- Generate the fip
fiptool update \
--nt-fw u-boot-nodtb.bin \
--hw-config u-boot.dtb \
<FIP location>/fip-stm32mp157c-ev1-optee.bin
2.2. With fragments[edit | edit source]
U-Boot configuration for Fastboot can be done by adding a fragment to the default configuration.
The fragment is different depending on the chosen boot storage:
- If the SD card is on mmc0, then it is the fragment fragment-04-fastboot_mmc0.fb_cfg
- If eMMC is on mmc1, then it is the fragment fragment-05-fastboot_mmc1.fb_cfg
Refer to STM32CubeProgrammer flashlayout for more information.
Fragments are delivered in the STM32 MPU Embedded Software Developer Package. They are also available on GitHub:
Follow these steps to enable Fastboot support on SD card on STM32MP157F-EV1 :
- Identify the mmc device number.
For the STM32MP157F-EV1 Evaluation board SD card is on mmc0.
- Append the corresponding fragment to the default configuration:
cat ../fragment-04-fastboot_mmc0.fb_cfg >> configs/stm32mp15_defconfig
- Build U-Boot using the SDK:
make -f $PWD/../Makefile.sdk UBOOT_DEFCONFIG=stm32mp15_defconfig DEVICETREE=stm32mp157f-ev1 all