dfu_mcuboot packet has unknown code out of bounds

[yang.hu]

Hi:

I am using nRF5340, NCS 3.1.99.

My software arch is bo+MCUboot+app(appcore + netcore).

After building my project, some unknown code in that file, which named 'signed_by_mcuboot_and_b0_s0_image_test_update.hex' and 'signed_by_mcuboot_and_b0_s1_image_test_update.hex'.

In the first file:

:020000040007F3
:103FF00077C295F360D2EF7F3552500F2CB679809F
:00000001FF

and the second file:

:020000040008F2
:103FF00077C295F360D2EF7F3552500F2CB679809F
:00000001FF

Here is part of partitions.yml:

b0:
  address: 0x0
  end_address: 0x8000
  placement:
    after:
    - start
  region: flash_primary
  size: 0x8000

mcuboot:
  address: 0x8200
  end_address: 0x14200
  placement:
    before:
    - mcuboot_primary
  region: flash_primary
  sharers: 0x1
  size: 0xc000

s0:
  address: 0x8000
  end_address: 0x14200
  orig_span: &id005
  - s0_pad
  - mcuboot
  region: flash_primary
  size: 0xc200
  span: *id005
s1:
  address: 0x18000
  end_address: 0x24200
  orig_span: &id007
  - s1_pad
  - s1_image
  region: flash_primary
  size: 0xc200
  span: *id007
app:
  address: 0x28200
  end_address: 0x94000
  region: flash_primary
  size: 0x6be00

We can see some code at the 0x73FF0 and 0x83FF0. And the unkonwn code destroy application.

Any suggestion?

[Naeem Maroof]

Devin Hu,

Thank you for contacting DevZone at NordicSemi.

I have been assigned this ticket. However, to look more into this, I would request if you could send your configuration and project files to build, see and dig more.

Regards,
Naeem

[yang.hu]

Hi,

Thanks for you reply. Here you go:

16504.hello_world.zip

You can build it by using board name 'nrf5340dk_nrf5340_cpuapp'. Then open the two hex files, you can see that unknown code at the end.

Regards,

devin hu

[Naeem Maroof]

Hi Devin,

Thank you for sending you configurations.

I can see what you were pointing to.

I don't think this is the problem. To test this, I just built an unofficial sample (bootloader_sample_git) for another DK. I browsed to the image_test_update.hex and you can see the last three lines matches with your case. 

[yang.hu]

Hi Naeem,

The last three lines shows there are some code in the 0x83ff0, but this address is application region.

Flash this hex file, the application will be changed.

or my thinking is wrong?

Regards,

Yang Hu

[Naeem Maroof]

Hi Devin,

The address 0x83ff0 is within flash region of memory map 5340.

These lines are related to the signing of the mcuboot. Metadata are placed after the end of the image. For the bootloader to be able to determine the current state and what actions should be taken during the current boot operation, it uses metadata stored in the image flash area. This metadata is located at the end of the image flash areas and is called image trailer. You can read more about it here: Image Trailer