MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Glenn Andrews — Thu, 04 Dec 2025 16:23:30 GMT

HI Vidar,

Yes, we're going to try and upstream something, get some input from the larger community.

Thanks

Glenn

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Vidar Berg — Thu, 04 Dec 2025 15:53:31 GMT

I'm glad to see you found a workaround for this, thank you for the update. I did spend some time on this comparing elf files, linker scripts and map files but did not manage to narrow it down to these linker sections like you did. However, I found following PRs which shows that we have seen this issue with the Zephyr SDK as well:

https://github.com/zephyrproject-rtos/zephyr/pull/89577

https://github.com/zephyrproject-rtos/zephyr/pull/89574

Although these commits do not explain why I'm only able to trigger the warning now with the GNU ARM embedded toolchain. Are you planning follow up on this in upstream Zephyr? If not, I can create a report in our bug tracker so we can track the issue internally.

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Glenn Andrews — Wed, 03 Dec 2025 23:15:03 GMT

We found a workaround in the Zephyr source code:

in zephyr/include/zephyr/linker/iterable_sections.h:

#define ITERABLE_SECTION_ROM(struct_type, subalign) \
  SECTION_PROLOGUE(struct_type##_area, (READONLY),) \
  { \
    Z_LINK_ITERABLE(struct_type); \
  } GROUP_ROM_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)

The difference is adding (READONLY) to the SECTION_PROLOGUE

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Glenn Andrews — Wed, 03 Dec 2025 16:13:22 GMT

I'll check with the Powers That Be.

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Vidar Berg — Wed, 03 Dec 2025 13:30:45 GMT

I have asked around and it does not appear to be a known issue. Internally we are using GCC from the Zephyr SDK which means we have limited or no test coverage with this toolchain. I also tried Zephyr SDK v1.0.0-beta1 which includes GCC 14.3.0 but that did not trigger in this warning either. Is using the Zephyr SDK with arm-zephyr-eabi-gcc an option for you? This is the recommended toolchain and it greatly reduces the build times when using picolib.

It may also be worth adding that the MPU driver is configured to prevent execution from RAM by default.

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Vidar Berg — Mon, 01 Dec 2025 16:55:18 GMT

Thank you for confirming. I was able to reproduce the same now just by building "Hello World" without the bootloader. I will investigate further and check with the developers whether this may be a known issue. I was on GCC version 12.2.0 prior to this.

arm-zephyr-eabi-gcc --version
arm-zephyr-eabi-gcc (Zephyr SDK 0.17.0) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Glenn Andrews — Mon, 01 Dec 2025 16:13:05 GMT

We're using gcc-arm-none-eabi 12.2-Rel1

Somewhere around GCC 12 they added this warning, before that it was ignored.

RE: MCUboot: warning: zephyr/zephyr_pre0.elf has a LOAD segment with RWX permissions

Vidar Berg — Mon, 01 Dec 2025 16:09:00 GMT

Hello,

Thank you for reporting. I don’t recall seeing reports of this error before, and the issue discussed in the linked Q&A is for TF-M, which I think may be a bit different since it’s built as an external project in Zephyr. Could you please let me know which toolchain and toolchain version you’re using so I can try to reproduce the same here? Is it the NCS toolchain or one of the others listed here?: https://docs.nordicsemi.com/bundle/ncs-3.2.0-preview3/page/zephyr/develop/toolchains/index.html?

Best regards,

Vidar