Background DFU update problem on NRF52832

RE: Background DFU update problem on NRF52832

Edvin — Tue, 02 Apr 2019 12:17:27 GMT

Hello,

I just spoke with one of our developers, and he told me that they have had a few issues with the TFTP DFU in SDK15.2.0. He suggested that you tested with SDK15.3.0 instead. He told me that there were several bug fixes, so it would be easier to start with SDK15.3.0 rather than porting the TFTP part only to SDK15.3.0.

BR,

Edvin

RE: Background DFU update problem on NRF52832

amaesa — Mon, 25 Mar 2019 18:00:42 GMT

Edvin, I actually managed to debug the bootloader right after reset.

In brief:

1) Right at bootloader start, the content of the bootloader settings page (0x7f000) looks OK to me:
This is what I see

crc = 333798234
settings_version = 1
app_version = 2
bootloader_version = 0
bank_layout = 0
bank_current = 1
bank_0    {...}
   image_size = 85720
   image_crc = 3998993418
   bank_code = 0
bank_1 {...}
   image_size = 85720
   image_crc = 598733133
   bank_code = 1

2) The page is unfortunately overwritten before being activated, because the function nrf_dfu_settings_init in nrf_bootloader_init detects that settings_forbidden_parts_equal_to_backup returns false.
From what I can see this is comparing the first 32 bytes (offset by 4 bytes) of the bootloader_settings (0x7f000) page and the backup settings page (0x7e000), finding a difference (below what I have in the backup settings at 0x7e000)

crc = 863167636
settings_version = 1
app_version = 1
bootloader_version = 0
bank_layout = 0
bank_current = 0
bank_0       {...}
   image_size = 85720
   image_crc = 3998993418
   bank_code = 1
bank_1   nrf_dfu_bank_t   {...}
   image_size = 0
   image_crc = 0
   bank_code = 0

which clearly differs from what at 0x7fff, causing the bootloader settings page to be overwritten, and the update ignored. A warning is thrown "Restoring settings from backup since the app has tampered with the off-limit parts of the settings page."

Why this happens, is still unclear to me.

RE: Background DFU update problem on NRF52832

amaesa — Mon, 25 Mar 2019 16:48:39 GMT

Hello Edvin, we need to use the background bootloader as it seems is the only way to update the FW from application code. We are receiving the upgrade among other data from another microcontroller, and still performing some local operations with this data before starting the upgrade with the background bootloader.

The background bootloader seems the only way to upgrade from application code to me.

RE: Background DFU update problem on NRF52832

Edvin — Thu, 21 Mar 2019 10:03:31 GMT

Is there any reason why you are using the background bootloader? Have you tested the normal bootloader:

https://devzone.nordicsemi.com/blogs/1085/getting-started-with-nordics-secure-dfu-bootloader/

It is easier to use, and a lot more tested. It uses the same bootloader as you refer to. Can you go through the guide, and see whether you get the same error?

Also, how do you generate your DFU image?

BR,

Edvin

RE: Background DFU update problem on NRF52832

amaesa — Thu, 21 Mar 2019 08:18:54 GMT

using the bootloader in components/libraries/bootloader/nrf_bootloader.c

RE: Background DFU update problem on NRF52832

Edvin — Thu, 21 Mar 2019 08:15:23 GMT

Are you using the bootloader from the IoT SDK, or the BLE bootloader?

RE: Background DFU update problem on NRF52832

amaesa — Wed, 20 Mar 2019 16:14:29 GMT

Few further info out of debugging:

In fact, even commenting out the lines I provided above, although the DFU process completes with a DFU_STATE_COMPLETED, the bootloader does not actually install the update.

This is strange because:
1) If we check the bootloader_settings information (at 0x7f000, reading the memory with the debugger (right after the DFU_STATE_COMPLETED and before the reset of the application to enter bootloader), the settings contain correctly an invalidated bank_0 code, and in bank_1 code a valid app code.
2) At reset, this does not seem to be considered by the bootloader.

For example, what we got right before reset:

Bank 0
image_size uint32_t 93144
bank_code uint32_t 0

Bank 1
image_size uint32_t 93148
bank_code uint32_t 1

which looks fine for me, as indicates bank1 contains the new upgrade, however after reset, this is not installed, and actually in 0x7f000 we found only information on Bank0 (the original ones) and nothing in Bank1 info (all 0s)

RE: Background DFU update problem on NRF52832

Edvin — Wed, 20 Mar 2019 14:59:01 GMT

Have you tried the non-background bootloader? Can you try it? Just to see whether you get the same issue there.

Please follow this guide:

https://devzone.nordicsemi.com/b/blog/posts/getting-started-with-nordics-secure-dfu-bootloader

To be honest, I am not sure how the background bootloader works. I haven't tested it. But if you get a similar issue here, it would be easier to reproduce and pin point the issue.

If the issue doesn't happen on the "normal" bootloader. Can you give me some hints on what you have done, so that I can try to reproduce it?

BR,

Edvin

RE: Background DFU update problem on NRF52832

amaesa — Tue, 19 Mar 2019 08:50:18 GMT

NRF_DFU_SETTINGS_ALLOW_UPDATE_FROM_APP is set to true, therefore the first branch of settings_forbidden_parts_equal_to_backup is executed, leading to a call of settings_region_compare_to_backup() returning false, called with the following values:
start_offset = 4
end_offset = 36
p_compare_addr = 0x2000c5d8 pointing to s_dfu_settings

1) No idea why this fails
2) Yes we use public / private keyset
3) Not sure I understand your question.
To generate the DFU image we do in sequence only the following:
- compile the application and generate an .hex
- Run nrfutil pkg generate on the .hex to generate a .zip file, providing the privatekey file
- Run trigger_creator.py on the .zip file and the config.json file

RE: Background DFU update problem on NRF52832

Edvin — Mon, 18 Mar 2019 11:44:04 GMT

Ok. Can you see what part of settings_forbidden_parts_equal_to_backup that returns false? Look in nrf_dfu_settings.c from line 197. Try to debug through it to see why it fails.

Do you have any suspicion why this might fail? Are you using a public + private keyset? Are you trying to merge the BL settings page with your application before creating a DFU image with it?

Best regards,

Edvin

RE: Background DFU update problem on NRF52832

amaesa — Fri, 15 Mar 2019 13:31:37 GMT

Hello,

I am referring to the NRF SDK 15.2 (nRF5_SDK_15.2.0_9412b96)

NRF_DFU_SETTINGS_IN_APP is set to 1 in the sdk_config.h, the "offending" code should be in settings_forbidden_parts_equal_to_backup.

Thank you for looking into this.

RE: Background DFU update problem on NRF52832

Edvin — Fri, 15 Mar 2019 13:25:11 GMT

Hello,

You are talking about the "normal" SDK, right?

So which one of these are triggering?

Is NRF_DFU_SETTINGS_IN_APP true, or is settings_forbidden_parts_equal_to_backup(...) returning false (and hence !settings_forbidden... returns true) ?