Using MCUBoot with nRF5340

[Torsten Robitzki]

Hello,

I try to figure out, how to correctly setup MCUboot for an nrf5340, so that:

• Application is updatable
• BT Stack is updatable
• Firmware Updates are encrypted and signed
• Updates are stored in external flash memory
• No need to update the bootloader itself
• Updates are stored on the external flash by some application specific protocol.

For that task, I upgraded our project to nrfconnect/sdk-nrf version v2.7.99-cs2. My current understanding is, that I want to use Sysbuild and have to define a static partition. I haven't found any comprehensive documentation, that defines exactly, which partitions are required for the given setup. So, I search for something in the examples, that could come close to my setup. The result of this example `pm_static.yml` looks like this:

app:
  address: 0x10200
  region: flash_primary
  size: 0xdfe00
mcuboot:
  address: 0x0
  region: flash_primary
  size: 0x10000
mcuboot_pad:
  address: 0x10000
  region: flash_primary
  size: 0x200
mcuboot_primary:
  address: 0x10000
  region: flash_primary
  size: 0xe0000
  span: [mcuboot_pad, app]
mcuboot_primary_app:
  address: 0x10200
  region: flash_primary
  size: 0xdfe00
  span: [app]
settings_storage:
  address: 0xf0000
  region: flash_primary
  size: 0x10000
mcuboot_primary_1:
  address: 0x0
  size: 0x40000
  device: nordic_ram_flash_controller
  region: ram_flash
mcuboot_secondary:
  address: 0x00000
  size: 0xe0000
  device: DT_CHOSEN(nordic_pm_ext_flash)
  region: external_flash
mcuboot_secondary_1:
  address: 0xe0000
  size: 0x40000
  device: DT_CHOSEN(nordic_pm_ext_flash)
  region: external_flash
external_flash:
  address: 0x120000
  size: 0x6e0000
  device: DT_CHOSEN(nordic_pm_ext_flash)
  region: external_flash
pcd_sram:
  address: 0x20000000
  size: 0x2000
  region: sram_primary

However, in the resulting `partition_manager_report`:

  external_flash (0x800000 - 8192kB): 
+------------------------------------------------+
| 0x0: mcuboot_secondary (0xe0000 - 896kB)       |
| 0xe0000: mcuboot_secondary_1 (0x40000 - 256kB) |
| 0x120000: external_flash (0x6e0000 - 7040kB)   |
+------------------------------------------------+

  flash_primary (0x100000 - 1024kB): 
+--------------------------------------------------+
| 0x0: mcuboot (0x10000 - 64kB)                    |
+---0x10000: mcuboot_primary (0xe0000 - 896kB)-----+
| 0x10000: mcuboot_pad (0x200 - 512B)              |
+---0x10200: mcuboot_primary_app (0xdfe00 - 895kB)-+
| 0x10200: app (0xdfe00 - 895kB)                   |
+--------------------------------------------------+
| 0xf0000: settings_storage (0x10000 - 64kB)       |
+--------------------------------------------------+

  otp (0x2fc - 764B): 
+------------------------------+
| 0xff8100: otp (0x2fc - 764B) |
+------------------------------+

  sram_primary (0x80000 - 512kB): 
+-----------------------------------------------+
| 0x20000000: pcd_sram (0x2000 - 8kB)           |
| 0x20002000: sram_primary (0x6e000 - 440kB)    |
| 0x20070000: rpmsg_nrf53_sram (0x10000 - 64kB) |
+-----------------------------------------------+

the partition `mcuboot_primary_1` is simply missing (and later the compilation of `nrf/modules/mcuboot/hooks/nrf53_hooks.c` fails with an undeclared symbol `PM_MCUBOOT_PRIMARY_1_ADDRESS`. 

I found this warning in the DTS parsing:

warning: FLASH_SIMULATOR (defined at drivers/flash/Kconfig.simulator:6) was assigned the value 'y'
but got the value 'n'. Check these unsatisfied dependencies: DT_HAS_ZEPHYR_SIM_FLASH_ENABLED (=n).
See http://docs.zephyrproject.org/latest/kconfig.html#CONFIG_FLASH_SIMULATOR and/or look up
FLASH_SIMULATOR in the menuconfig/guiconfig interface.

The referenced documentation just contains the sentence: "Enable the flash simulator."

What do I have to do, to use MCUBoot? 

Is there any comprehensive documentation, that clearly states, what is required to completely configure the bootloader?

[Vidar Berg]

Hi Torsten,

Torsten Robitzki said:

Thanks for the example, but it doesn't build correctly (board is unknown). When I change the board to  `nrf5340dk/nrf5340/cpuapp` I get some configuration warnings:

Sorry, I see now that it is only compatible with the SPI NOR driver, not the QSPI NOR driver. This means that if you want to test it, you would have to place the external flash device on a SPI bus and use the `jedec,spi-nor` binding instead of "nordic,qspi-nor". The SPI flash sample works with QSPI, but it does not read the JDEC information.

Torsten Robitzki said:

That's the major problem with examples. You never know, which bit is really important. Is the name of the key file important? Sure, I could have copied your entire example, but then I would also end up with an application, that does exactly what your example does. Unfortunately, that's not what my customer needs ;-)

I understand the challenges, and I hope this is something we can improve on. This is particularly a problem with the 53 series, as there are quite a few additional configuration options to handle multi-image DFU.

Best regards,

Vidar