MCUBoot "reading sectors failed" problem with nrf-sdk v1.6.0

[n.marty]

Hi all

We are switching to nrf-sdk v1.6.0 in our project and encountered a problem with MCUBoot.

The image builds successfully and can be flashed successfully as well. MCUBoot loads but is then unable to find a bootable image. There's a message which says:

W: Failed reading sectors; BOOT_MAX_IMG_SECTORS=128 - too small?

I tried increasing BOOT_MAX_IMG_SECTORS up to 91216. But there's still the same error message. I can't increase it more otherwise it overlaps SRAM region. I think the problem is somewhere else but I don't know where. Can someone give me a hint where to look for the problem?

I read that BOOT_MAX_IMG_SECTORS configuration is important for swapping the image in the secondary slot to the primary slot after an update.
I thought as a workaround I could configure MCUBoot to work in XIP Mode "execute in place", which does not need swapping and thus my initial problems disappears. Does anyone have a recommendation if it is a good idea to use XIP?

best regards

[n.marty]

Attached below the contents of the partitions.yml. This corresponds to the configuration from my previous posts.

EMPTY_0:
  address: 0xc000
  end_address: 0x10000
  placement:
    before:
    - mcuboot_pad
  region: flash_primary
  size: 0x4000
app:
  address: 0x20200
  end_address: 0x88000
  region: flash_primary
  size: 0x67e00
mcuboot:
  address: 0x0
  end_address: 0xc000
  placement:
    before:
    - mcuboot_primary
  region: flash_primary
  size: 0xc000
mcuboot_pad:
  address: 0x10000
  end_address: 0x10200
  placement:
    align:
      start: 0x8000
    before:
    - mcuboot_primary_app
  region: flash_primary
  size: 0x200
mcuboot_primary:
  address: 0x10000
  end_address: 0x88000
  orig_span: &id001
  - app
  - mcuboot_pad
  - spm
  region: flash_primary
  sharers: 0x1
  size: 0x78000
  span: *id001
mcuboot_primary_app:
  address: 0x10200
  end_address: 0x88000
  orig_span: &id002
  - app
  - spm
  region: flash_primary
  size: 0x77e00
  span: *id002
mcuboot_secondary:
  address: 0x88000
  end_address: 0x100000
  placement:
    after:
    - mcuboot_primary
    align:
      start: 0x8000
  region: flash_primary
  share_size:
  - mcuboot_primary
  size: 0x78000
nrf_modem_lib_ctrl:
  address: 0x20010000
  end_address: 0x200104e8
  inside:
  - sram_nonsecure
  placement:
    after:
    - spm_sram
    - start
  region: sram_primary
  size: 0x4e8
nrf_modem_lib_rx:
  address: 0x200124e8
  end_address: 0x200144e8
  inside:
  - sram_nonsecure
  placement:
    after:
    - nrf_modem_lib_tx
  region: sram_primary
  size: 0x2000
nrf_modem_lib_sram:
  address: 0x20010000
  end_address: 0x200144e8
  orig_span: &id003
  - nrf_modem_lib_ctrl
  - nrf_modem_lib_tx
  - nrf_modem_lib_rx
  region: sram_primary
  size: 0x44e8
  span: *id003
nrf_modem_lib_tx:
  address: 0x200104e8
  end_address: 0x200124e8
  inside:
  - sram_nonsecure
  placement:
    after:
    - nrf_modem_lib_ctrl
  region: sram_primary
  size: 0x2000
otp:
  address: 0xff8108
  end_address: 0xff83fc
  region: otp
  size: 0x2f4
spm:
  address: 0x10200
  end_address: 0x20200
  inside:
  - mcuboot_primary_app
  placement:
    before:
    - app
  region: flash_primary
  size: 0x10000
spm_sram:
  address: 0x20000000
  end_address: 0x20010000
  inside:
  - sram_secure
  placement:
    after:
    - start
  region: sram_primary
  size: 0x10000
sram_nonsecure:
  address: 0x20010000
  end_address: 0x20040000
  orig_span: &id004
  - sram_primary
  - nrf_modem_lib_ctrl
  - nrf_modem_lib_tx
  - nrf_modem_lib_rx
  region: sram_primary
  size: 0x30000
  span: *id004
sram_primary:
  address: 0x200144e8
  end_address: 0x20040000
  region: sram_primary
  size: 0x2bb18
sram_secure:
  address: 0x20000000
  end_address: 0x20010000
  orig_span: &id005
  - spm_sram
  region: sram_primary
  size: 0x10000
  span: *id005

Thank you for looking into it.

best regards

[Albrecht Markus Schellenberger]

Hello Nicolas,

Have you already tried to do a fresh build by deleting the build folder and recompile the whole application?

If that doesn’t help you could give it a shot flashing the MCUboot only from the HTTP application update sample to a device with the failing application.

Can be done by using:

nrfjprog --program *.hex --sectorerase

File located in <build_dir>/mcuboot/zephyr/zephyr.hex

Regards,

Markus

[n.marty]

I deleted the build directory and did a clean build. Unfortunately this did not help.

Next I tried to flash the MCUBoot from the http update sample wiith your provided command. The "failed reading sectors" error disappeard but it is still not able to find a bootable image:

Here's the output after flashing MCBoot only:
I: Starting bootloader
I: Primary image: magic=unset, swap_type=0x1, copy_done=_ok=0x3
I: Boot source: none
I: Swap type: none
E: Image in the primary slot is not valid!
E: Unable to find bootable image

best regards

[Albrecht Markus Schellenberger]

Thanks a lot for the feedback, Nicolas!

Something seems to be wrong with the bootloader image in your application, then. I’m afraid I can not tell you much more than this at the moment.

When building the application in NCS v1.6.0, does the compiler throw any warnings or something that is different compared to the build in NCS you are switching from?

Regards,

Markus

[n.marty]

Hi Markus

I found the problem. As you said, the bootloader image had a problem. And this problem was introduced by the following CMake snippet which is part of our project CMakeLists.txt:

if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/mcuboot.conf")
list(APPEND mcuboot_OVERLAY_CONFIG
        "${CMAKE_CURRENT_SOURCE_DIR}/mcuboot.conf")
endif()

This worked fine for the previous version, but for 1.6 this is breaking the MCUBoot build configuration for some reason. Unfortunately I couldn't see any hint about a problem in the build output...

The intention of this script is to append project specific configuration to MCUBoot, namely which key to use for the signature check, which key algorithm, etc.

I am now looking for a solution to append my MCUBoot config without modifying the external source files.
Do you know how this can be done? Or anyone else has an idea?

best regards