Direct Kernel Boot on STM32MP1

[HZ890]

Hi everyone,

I'm attempting to optimize the boot process on my STM32MP157F-DK2 board by removing U-Boot and booting the Linux kernel directly via the FIP. I've followed the documented steps for STM32MP1:

1. TF-A BL2 Modifications:

   • Updated STM32MP_BL33_BASE and STM32MP_BL33_MAX_SIZE in the STM32MP1 header file.

   • Increased the SDMMC timeout in stm32_sdmmc2.c to accommodate the larger kernel image.

2. FIP Creation:

   • Recompiled TF-A with my modifications.

   • Created a new FIP where I replaced the U-Boot binary and its DTB with my Linux kernel Image and DTB.

   • The new FIP (fip.bin) now contains the kernel and DTB.

3. Flash Layout TSV Modifications:
   I updated the TSV file to allocate a larger space for the FIP. Below is the relevant excerpt:

   

Despite these modifications, every time I execute the process, it fails. My questions are:

• What is the purpose of the bootfs partition?
  Since my new FIP (fip.bin) already contains the Linux kernel and its DTB, I'm unclear why the flash layout still reserves a bootfs partition. Is it meant for additional boot configurations, an initial ramdisk, or something else?

• Why is the u-boot-env partition still present?
  If U-Boot is being removed entirely from the boot chain, what role does the U-Boot environment play here? Is it kept for legacy or recovery purposes?

I would really appreciate any insights or suggestions on what might be going wrong or what additional changes I need to consider for a successful direct kernel boot setup on STM32MP157f-dk2.

Thanks in advance for your help!

[Erwan SZYMANSKI]

Hello @HZ890 ,
Can you please precise a bit the status when you says "everytime I execute the process it fails" ? Do you talk at boot time or during the preparation process ? 

Do you have some error logs or anything to share ? 

Kind regards,
Erwan.

[HZ890]

Dear Erwan SZYMANSKI,

I received the following error during the boot time process:

NOTICE: CPU: STM32MP157FAC Rev.Z NOTICE: Model: STMicroelectronics STM32MP157F-DK2 Discovery Board NOTICE: Board: MB1272 Var4.0 Rev.C-03 NOTICE: BL2: v2.10-stm32mp1-r1.0(release):() NOTICE: BL2: Built : 11:26:24, Apr 7 2025 ERROR: BL2: Failed to load image id 1 (-27)

If you have any pointers or an example with those platforms, it would be much appreciated.

Best Regards,
Hassan

[Erwan SZYMANSKI]

Hello @HZ890 ,
First, concerning the mention of bootfs partition and u-boot-env are no more needed in this setup, the article just wanted to make a parallel with the default components / flashlayout, but you are right I will remove it in the next version of the article. 

Then concerning your image load error, can you activate more TF-A  debug logs and give an attachment of all the bootlogs ? 

Kind regards,
Erwan.

[HZ890]

Hi Erwan,

I wanted to update you on my progress with the STM32MP157F boot sequence. I've removed U-Boot from the boot sequence and configured the system to boot directly into Linux, as suggested in the guide https://wiki.st.com/stm32mpu/wiki/How_to_optimize_the_boot_time#Optimizing_boot-time_by_removing_U-Boot .

Here are the steps I followed:

1. TF-A Configuration:

   • Updated the configuration for STM32MP_BL33_BASE and STM32MP_BL33_MAX_SIZE:

     #define STM32MP_BL33_BASE (STM32MP_DDR_BASE + U(0x2008000))

     #define STM32MP_BL33_MAX_SIZE U(0x3FF8000)

2. SD Card Timeout Modification:

   • Changed the SD card timeout in <tf-a_sources>/drivers/st/mmc/stm32_sdmmc2.c:

     timeout = timeout_init_us(TIMEOUT_US_1_S * 10);

3. TF-A Build Process:

   • Extracted TF-A and applied patches:

     $> tar xf tf-a-stm32mp-v2.10.5-stm32mp-r1-r0.tar.xz
     $> cd tf-a-stm32mp-v2.10.5-stm32mp-r1

     $> for p in `ls -1 ../*.patch`; do patch -p1 < $p; done

     $> export FIP_DEPLOYDIR_ROOT=$PWD/../../FIP_artifacts

     $> make -f ../Makefile.sdk TF_A_DEVICETREE=stm32mp157f-dk2 TF_A_CONFIG=optee-sdcard ELF_DEBUG_ENABLE='1' all

   • The TF-A output files were:

     • tf-a-stm32mp157f-dk2-optee-sdcard.stm32

     • stm32mp157f-dk2-fw-config-optee-sdcard.dtb

4. Kernel Configuration:

   • I followed the instructions of:
     $> tar xf linux-6.6.48.tar.xz
     $> cd linux-6.6.48
     $> for p in `ls -1 ../*.patch`; do patch -p1 < $p; done

     $> export OUTPUT_BUILD_DIR=$PWD/../build
     $> mkdir -p ${OUTPUT_BUILD_DIR}
     $> make O="${OUTPUT_BUILD_DIR}" defconfig fragment*.config

     If there are some fragments, apply them
     * manually one by one:
     $ scripts/kconfig/merge_config.sh -m -r -O ${OUTPUT_BUILD_DIR} ${OUTPUT_BUILD_DIR}/.config ../fragment-01-xxx.config
     $ scripts/kconfig/merge_config.sh -m -r -O ${OUTPUT_BUILD_DIR} ${OUTPUT_BUILD_DIR}/.config ../fragment-02-xxx.config
     ...
     $ (yes '' || true) | make oldconfig O="${OUTPUT_BUILD_DIR}"

   • Used make menuconfig to configure the kernel command line:

     • (root=PARTUUID=e91c4e10-16e6-4c0e-bd0e-77becf4a3582 rootwait rw earlyprintk earlycon console=ttySTM0,115200)

     • Selected: Kernel command line type (Always use the default kernel command string)

   • Built the kernel:

     make Image vmlinux dtbs O="${OUTPUT_BUILD_DIR}"

   • This resulted in the output files:

     • Image

     • stm32mp157f-dk2.dtb

5. FIP Tool Update:

   • Used fiptool to update the binary files:

     fiptool update --fw-config stm32mp157f-dk2-fw-config.dtb --nt-fw Image --hw-config stm32mp157f-dk2.dtb fip-stm32mp157f-dk2-optee-sdcard.bin

   • The result was the new FIP file: fip-stm32mp157f-dk2-optee-sdcard.bin

6. Flash Layout Modification:

   • Modified the tsv file to include the new TF-A and FIP files:

     

7. Flashing the Board:

   • Connected the board using a USB Type-A to Type-C cable for data and a 5V 3A power adapter.

   • Used the command:

     STM32_Programmer_CLI -c port=usb1 -w flashlayout_st-image-weston/optee/FlashLayout_sdcard_stm32mp157f-dk2-optee-modif.tsv

   • Then powered off the board, switched the boot mode to ON, and powered it on.

8. Boot Log Output:

   • Upon powering the board, I received the following output:

     NOTICE: CPU: STM32MP157FAC Rev.Z
     NOTICE: Model: STMicroelectronics STM32MP157F-DK2 Discovery Board
     NOTICE: Board: MB1272 Var4.0 Rev.C-03
     INFO: PMIC version = 0x21
     INFO: Reset reason (0x15):
     INFO: Power-on Reset (rst_por)
     INFO: FCONF: Reading TB_FW firmware configuration file from: 0x2ffe2000
     INFO: FCONF: Reading firmware configuration information for: stm32mp_fuse
     INFO: FCONF: Reading firmware configuration information for: stm32mp_io
     INFO: Using SDMMC
     INFO: Instance 1
     INFO: Boot used partition fsbl1
     NOTICE: BL2: v2.10-stm32mp1-r1.0(debug):()
     NOTICE: BL2: Built : 14:04:05, Apr 15 2025
     INFO: BL2: Doing platform setup
     INFO: RAM: DDR3-DDR3L 16bits 533000kHz
     INFO: Memory size = 0x20000000 (512 MB)
     INFO: BL2: Loading image id 1
     INFO: Loading image id=1 at address 0x2ffff000
     INFO: Image id=1 loaded: 0x2ffff000 - 0x2ffff1ea
     INFO: FCONF: Reading FW_CONFIG firmware configuration file from: 0x2ffff000
     INFO: FCONF: Reading firmware configuration information for: dyn_cfg
     INFO: FCONF: Reading firmware configuration information for: stm32mp1_firewal
     INFO: BL2: Loading image id 4
     WARNING: Failed to access image id=4 (-2)
     ERROR: BL2: Failed to load image id 4 (-2)

Could you please take a look and let me know if I missed anything in the setup or if there is something else that could be causing this issue?

Looking forward to your guidance.

Kind regards,

Hassan

[Erwan SZYMANSKI]

Hello @HZ890 ,
Is it possible for you to attach your fip here ? It seems there is something wrong in the FIP content.

Kind regards,
Erwan.

[HZ890]

Hello Erwan,

Sure, please find the FIP file attached for your review.

Kind regards,

Hassan