MCUBOOT RAM_LOAD load and jump success but app crashes. STM32H7S78-DK #106010

Sambsc19 · 2026-03-22T03:33:03Z

Sambsc19
Mar 22, 2026

I am trying to use the RAM_LOAD feature of MCUBOOT on zephyr 4.2.0. I am running MCUBOOT from internal 64kb flash. I am storing a blinky sample in external flash to be copied to DTCM similar to this: https://community.nxp.com/t5/Zephyr-Project-Knowledge-Base/MCUboot-RAM-Loading-with-Zephyr/ta-p/2139539

Initially I had an issue jumping to the app because it was jumping to the header instead of the image which i resolved by disabling ARM_MPU and defining dtcm_app: memory@20000400 node in the application overlay so it jumps past the header. now the app starts and I can see OS logs printing stack pointer at 0x2000xxxx which is valid DCTM address. However after those logs the app crashes.

I believe the issue may be that zephyr,flash and zephyr,sram are both pointing to DTCM but as described in the article above this is required.

I have attached my overlay and conf files for both mcuboot and blinky app as well as the bin, hex and elf for each. I;ve also attached dissasembly. Has anyone got this running on stm32?

I am signing with this cmd:

imgtool sign --key C:/Partition_Environments/Pythons/zephyrproject/root-rsa-2048.pem --header-size 0x400 --align 4 --version 1.0.0 --slot-size 0x80000 --load-addr 0x20000000 --pad-header build/zephyr/zephyr.bin signed-hello-world.bin

Here are logs from printk:

*** Booting MCUboot v2.2.0-109-g14513a43cccd ***
*** Using Zephyr OS build v4.2.0-567-g7d4c236ec786 ***
I: Starting bootloader
I: Primary slot: version=1.0.0+0
I: Image 0 Secondary slot: Image not found
I: Image 0 RAM loading to 0x20000000 is succeeded.
I: Image 0 loaded from the primary slot
I: Bootloader chainload address offset: 0x20000000
I: Image version: v1.0.0
I: Jumping to the first image slot
I: RCC->AHB2ENR = 0x0
I: Checking SRAM at 0x20000400: 0x20007420***** BUS FAULT *****
  Imprecise data bus error
r0/a1:  0x00000000  r1/a2:  0x00002000  r2/a3:  0x20004718
r3/a4:  0x200015f1 r12/ip:  0x20007454 r14/lr:  0x20001607
 xpsr:  0x61000000
Faulting instruction address (r15/pc): 0x20001f2a

logs with CONFIG_LOG enabled:

I: Jumping to the first image slot
I: RCC->AHB2ENR = 0x0
I: Checking SRAM at 0x20000400: 0x2000a350[00:00:00.000,000] <dbg> os: setup_thread_stack: stack 0x20008350 for thread 0x20007408: obj_size=8192 buf_start=0x20008350  buf_size 8192 stack_ptr=0x2000a350
[00:00:00.000,000] <dbg> os: setup_thread_stack: stack 0x20008210 for thread 0x20007398: obj_size=320 buf_start=0x20008210  buf_size 320 stack_ptr=0x20008350
[00:00:00.000,000] <dbg> os: setup_thread_stack: stack 0x20007710 for thread 0x20006ed8: obj_size=768 buf_start=0x20007710  buf_size 768 stack_ptr=0x20007a10
[00:00:00.000,000] <err> os: ***** BUS FAULT *****
[00:00:00.000,000] <err> os:   Imprecise data bus error
[00:00:00.000,000] <err> os: r0/a1:  0x00000000  r1/a2:  0x00002000  r2/a3:  0x20006e04
[00:00:00.000,000] <err> os: r3/a4:  0x20007708 r12/ip:  0x2000a384 r14/lr:  0x200027a3
[00:00:00.000,000] <err> os:  xpsr:  0x61000000
[00:00:00.000,000] <err> os: Faulting instruction address (r15/pc): 0x2000324c
[00:00:00.000,000] <err> os: >>> ZEPHYR FATAL ERROR 26: Unknown error on CPU 0
[00:00:00.000,000] <err> os: Current thread: 0x20007408 (unknown)
[00:00:00.020,000] <err> os: Halting system

ram_load.zip

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MCUBOOT RAM_LOAD load and jump success but app crashes. STM32H7S78-DK #106010

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MCUBOOT RAM_LOAD load and jump success but app crashes. STM32H7S78-DK #106010

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Sambsc19 Mar 22, 2026

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Sambsc19
Mar 22, 2026