This article explains how to configure U-Boot to support Fastboot mode.
1. Fastboot[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.
2. Configure U-Boot to support Fastboot mode[edit source]
Fastboot is supported in U-Boot but it is not necessarily enabled by default.
A U-Boot binary, and so a fip, can support only one mass storage device for Fastboot.
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:
- 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 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 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