How do I change the application/bootloader start address?

RE: How do I change the application/bootloader start address?

klockhart — Mon, 22 Oct 2018 18:39:43 GMT

After looking into the allocation in the map file, it became apparent that the issue I was seeing was due to the bootloader sections not being allocated properly. While the sections in the linker script do need to be added, this is only part of what's needed.

As opposed to the examples given in the SDK, my build configuration file (CMakeLists.txt using cmake and ninja to build) was designed in a minimalistic way, including only bootloader_main.c and one support file, with the Nordic files available as a separate library. The bootloader sections are utilized in components/libraries/bootloader/dfu/nrf_dfu_settings.c and components/libraries/bootloader/nrf_bootloader_info.c. As bootloader_main.c was not referencing these files explicitly, they were not being included in the build and were not being given space in the bootloader map. Adding these files to the bootloader target explictly caused them to be allocated and enabled the bootloader to boot.

So the change I needed to make to the project was to go from this executable setup:

set (EXE_NAME "bootloader")
add_executable(bootloader
    $<TARGET_OBJECTS:nrf5_sdk_retarget> # This allows linking in the "retargetted versions of _read and _write
                                        # for printf/scanf instead of linking the libnosys implementation.
    ${APP_ROOT}/bootloader_main.c
    ${APP_ROOT}/shipBoot.c
)

To this one:

set (EXE_NAME "bootloader")
add_executable(bootloader
    $<TARGET_OBJECTS:nrf5_sdk_retarget> # This allows linking in the "retargetted versions of _read and _write
                                        # for printf/scanf instead of linking the libnosys implementation.
    ${APP_ROOT}/bootloader_main.c
    ${APP_ROOT}/shipBoot.c
	# There are a few bootloader sections which need to be allocated in the
	# final build. The following files add variables in the given sections,
	# resulting in their allocation in the map file.
	${NRF5_SDK_ROOT}/components/libraries/bootloader/dfu/nrf_dfu_settings.c
	${NRF5_SDK_ROOT}/components/libraries/bootloader/nrf_bootloader_info.c
)

RE: How do I change the application/bootloader start address?

klockhart — Fri, 19 Oct 2018 13:22:30 GMT

I've got this line under Memory Configuration:

uicr_bootloader_start_address 0x10001014         0x00000004         r

And this later on in the map file:

.uicr_bootloader_start_address
                0x10001014        0x0
                [!provide]                PROVIDE (__start_uicr_bootloader_start_address = .)
 *(SORT_BY_NAME(.uicr_bootloader_start_address*))
                [!provide]                PROVIDE (__stop_uicr_bootloader_start_address = .)

RE: How do I change the application/bootloader start address?

bjorn-spockeli — Fri, 19 Oct 2018 13:08:27 GMT

Hi Kathleen,
as long as you have the following memory regions and sections set in your linker script

MEMORY
{
  FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0x57000
  RAM (rwx) :  ORIGIN = 0x200057b8, LENGTH = 0xa848
  mbr_params_page (r) : ORIGIN = 0x0007E000, LENGTH = 0x1000
  bootloader_settings_page (r) : ORIGIN = 0x0007F000, LENGTH = 0x1000
  uicr_mbr_params_page (r) : ORIGIN = 0x10001018, LENGTH = 0x4
  uicr_bootloader_start_address (r) : ORIGIN = 0x10001014, LENGTH = 0x4
}

SECTIONS
{
  .mbr_params_page(NOLOAD) :
  {
    PROVIDE(__start_mbr_params_page = .);
    KEEP(*(SORT(.mbr_params_page*)))
    PROVIDE(__stop_mbr_params_page = .);
  } > mbr_params_page
  .bootloader_settings_page(NOLOAD) :
  {
    PROVIDE(__start_bootloader_settings_page = .);
    KEEP(*(SORT(.bootloader_settings_page*)))
    PROVIDE(__stop_bootloader_settings_page = .);
  } > bootloader_settings_page
  .uicr_mbr_params_page :
  {
    PROVIDE(__start_uicr_mbr_params_page = .);
    KEEP(*(SORT(.uicr_mbr_params_page*)))
    PROVIDE(__stop_uicr_mbr_params_page = .);
  } > uicr_mbr_params_page
  .uicr_bootloader_start_address :
  {
    PROVIDE(__start_uicr_bootloader_start_address = .);
    KEEP(*(SORT(.uicr_bootloader_start_address*)))
    PROVIDE(__stop_uicr_bootloader_start_address = .);
  } > uicr_bootloader_start_address
}

specifically the uicr_bootloader_start_address section, then you should be fine. Could you search through your .map file and see if uicr_bootloader_start_address section is included in the generated binary?

RE: How do I change the application/bootloader start address?

klockhart — Wed, 17 Oct 2018 17:57:00 GMT

I've noticed that my custom bootloader isn't setting the bootloader start address in the UICR registers. Is there anything specific in the project setup that signals nrfjprog that a given application is a bootloader and thus that the UICR registers should be set? I'm using the same ld file for my bootloader as for the example in the SDK, so maybe I'm missing something in the makefile?

RE: How do I change the application/bootloader start address?

bjorn-spockeli — Tue, 02 Oct 2018 13:49:17 GMT

I think the issue is that the length value is to large as ORIGIN+LENGTH is 0x81000. The bootloader should stop at the start of the MBR Params page at 0x7E000, i.e. LENGTH = 0x78000 - ORIGIN = 0x57000.

I tested the following setting with the bootlaoder in SDK v15.2.0 and I had no issues.

FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0x57000

RE: How do I change the application/bootloader start address?

klockhart — Tue, 02 Oct 2018 13:23:17 GMT

No, I am not able to debug with that configuration. I have been able to debug the bootloader with the FLASH (rx) : ORIGIN = 0x26000, LENGTH = 0x5a000 configuration.

RE: How do I change the application/bootloader start address?

bjorn-spockeli — Tue, 02 Oct 2018 06:42:44 GMT

Yes, you understanding is correct.

Are you able to debug the bootloader when you use the FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0x59000 configuration?

Best regards

Bjørn

RE: How do I change the application/bootloader start address?

klockhart — Mon, 01 Oct 2018 15:22:01 GMT

So if I'm understanding you right, the blinky application isn't working at another address because it has to be located immediately after the softdevice (i.e. 0x26000.) But the bootloader should be able to be placed pretty much anywhere in flash where's it's not overwriting the softdevice as the its start location is saved in the UICR registers.

When I switch over to using our custom bootloader, I'm seeing that when I set the flash configuration to FLASH (rx) : ORIGIN = 0x26000, LENGTH = 0x5a000, the bootloader boots up and prints to the debug port successfully, but when I set the flash configuration to FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0x59000, I don't see any output on the debug port, leading me to believe the bootloader is never being run. As part of my programming procedure I'm running an eraseall, which should make sure the UICR registers get reprogrammed and I'm also making sure to reset the board after programming everything. What am I missing here?

RE: How do I change the application/bootloader start address?

bjorn-spockeli — Mon, 01 Oct 2018 15:05:31 GMT

The SoftDevice will forward interrupts/events to the application and for the SoftDevice to locate the application interrupt vectors, the application must define its interrupt vector table at the bottom of the Application Flash Region illustrated in Memory resource map. When the base address of the application code is directly after the top address of the SoftDevice, the code can be developed as a standard ARM® Cortex® -M4 application project with the compiler creating the interrupt vector table, see Interrupt forwarding to the application for more information.

In other words, the application must start right after the SoftDevice. The bootloader can be placed anywhere above the application as the MBR will find the bootloader start address in the UICR registers and then forward interrupts to that address, see Master boot record and bootloader for more information.

RE: How do I change the application/bootloader start address?

klockhart — Mon, 01 Oct 2018 14:14:51 GMT

So that explains why 0x25000 won't work as a start address, but I also can't run the blinky example with the following configuration: FLASH (rx) : ORIGIN = 0x27000, LENGTH = 0x59000. Any idea what might be going on here?

RE: How do I change the application/bootloader start address?

bjorn-spockeli — Mon, 01 Oct 2018 13:01:59 GMT

Hi Kathleen,

the S132 v6.1.0 SoftDevice requires 152 kB (0x26000 bytes) of program memory, starting from 0x0000 ( This is included the MBR, see Memory resource map and usage for the memory layout). So when you are setting the application or bootloader start address to 0x25000, you are effectively overwritting the SoftDevice. Hence setting any start address higher than 0x26000 should work fine for both the bootloader and the application.

Best regards
Bjørn