NRF52840 Bare Metal - Linker Script not found

[DBS06]

Description

Hi,
I already build successfully a custom bootloader with mbed-dev, but to maintain another repository is expensive in time and costs, I tried to build a bare-metal bootloader application with mbed-os 5.12.3, but the compilation fails with an error which says no linker script found.

mbed compile --profile .\profiles\bootloader.json -m NRF52840_DK --build BUILD_RELEASE -t GCC_ARM --app-config .\_____\_____\cfg\mbed_app.json
[mbed] WARNING: If you're using Python 3 with Mbed OS 5.8 and earlier versions, Python errors will occur when compiling, testing and exporting
---
[mbed] Working path "P:\________" (program)
Building project _________-app (NRF52840_DK, GCC_ARM)
Scan: _________-app
Using ROM regions application, post_application in this build.
  Region application: size 0x6000, offset 0x0
  Region post_application: size 0xfa000, offset 0x6000
No Linker Script found

Could not compile for NRF52840_DK: No Linker Script found
[mbed] ERROR: "c:\program files (x86)\python37-32\python.exe" returned error.
       Code: 1
       Path: "P:\_____________"
       Command: "c:\program files (x86)\python37-32\python.exe -u P:\_____________\mbed-os\tools\make.py -t GCC_ARM -m NRF52840_DK --profile .\profiles\bootloader.json --source . --build BUILD_RELEASE --app-config .\_______\bootloader-app\cfg\mbed_app.json"
       Tip: You could retry the last command with "-v" flag for verbose output
---
[mbed] WARNING: Using Python 3 with Mbed OS 5.8 and earlier can cause errors with compiling, testing and exporting

If I remove

    "requires": [
        "bare-metal"
    ],

from my mbed_app.json, mbed compile finds the Linker Script for the NRF52840.
What could be the reason for this?
With a different target (i.e. EFM32PG12_STK3402) it works.

mbed compile --profile .\profiles\bootloader.json -m EFM32PG12_STK3402 --build BUILD_RELEASE -t GCC_ARM --app-config .\_______\bootloader-app\cfg\mbed_app.json --clean
[mbed] WARNING: If you're using Python 3 with Mbed OS 5.8 and earlier versions, Python errors will occur when compiling, testing and exporting
---
[mbed] Working path "P:\_____________" (program)
Building project _________-app (EFM32PG12_STK3402, GCC_ARM)
Scan: ng-master-app
Using ROM regions application, post_application in this build.
  Region application: size 0x6000, offset 0x0
  Region post_application: size 0xfa000, offset 0x6000
Compile [  0.4%]: except.S
Compile [  0.9%]: mbed_tz_context.c
Compile [  1.3%]: mbed_fault_handler.c
Compile [  1.8%]: Ethernet.cpp
Compile [  2.2%]: CAN.cpp
...

I looked inside the target folders and configuration files for this two targets and compared them, but I didn't found obvious differences which could explain this.
I would be really grateful if somebody could look inside this issue!

Issue request type

[X] Question
[ ] Enhancement
[X] Bug

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-1219

[DBS06]

Any idea where I can start to search inside the mbed tools?

[0xc0170]

build_api.py has this there

        # Change linker script if specified
        if linker_script is not None:
            resources.add_file_ref(FileType.LD_SCRIPT, linker_script, linker_script)
        if not resources.get_file_refs(FileType.LD_SCRIPT):
            notify.info("No Linker Script found")
            raise NotSupportedException("No Linker Script found")

I would check why there is no .ld file found in the resources object (just print it to check) . Check paths if your target is getting included (TARGET_ missing - label?).

It should be fairly simple to find out once you get resources object

[DBS06]

@0xc0170 thanks for the reply!
I added

        # Change linker script if specified
        notify.info("linker_script: " + str(resources.get_file_refs(FileType.LD_SCRIPT)))
[...]

Result:

    mbed compile -m NG_NRF52840_BOOT_DK --app-config p:\ng-master-app\ng-apps\bootloader-app\cfg\mbed_app.json --profile p:\ng-master-app\profiles\release.json --build p:\ng-master-app\BUILD_RELEASE\bootloader-app\NG_NRF52840_BOOT_DK -vv 
	env: None
Building project ng-master-app (NG_NRF52840_BOOT_DK, GCC_ARM)
Scan: ng-master-app
Using ROM regions application, post_application in this build.
  Region application: size 0x6000, offset 0x0
  Region post_application: size 0xfa000, offset 0x6000
linker_script: []
No Linker Script found

without

    "requires": [
        "bare-metal"
    ],

Result:

    mbed compile -m NG_NRF52840_BOOT_DK --app-config p:\ng-master-app\ng-apps\bootloader-app\cfg\mbed_app.json --profile p:\ng-master-app\profiles\release.json --build p:\ng-master-app\BUILD_RELEASE\bootloader-app\NG_NRF52840_BOOT_DK -vv 
	env: None
Building project ng-master-app (NG_NRF52840_BOOT_DK, GCC_ARM)
Scan: ng-master-app
Using ROM regions application, post_application in this build.
  Region application: size 0x6000, offset 0x0
  Region post_application: size 0xfa000, offset 0x6000
linker_script: [FileRef(name='mbed-os\\targets\\TARGET_NORDIC\\TARGET_NRF5x\\TARGET_NRF52\\TARGET_MCU_NRF52840\\device\\TOOLCHAIN_GCC_ARM\\NRF52840.ld', path='.\\mbed-os\\targets\\TARGET_NORDIC\\TARGET_NRF5x\\TARGET_NRF52\\TARGET_MCU_NRF52840\\device\\TOOLCHAIN_GCC_ARM\\NRF52840.ld')]
Macros: -DTARGET_NAME=NG_NRF52840_BOOT_DK -DDEVICE_I2C=1 -DTARGET_SDK_14_2 -DMBED_BUILD_TIMESTAMP=1559045413.0244005 -DTARGET_FF_ARDUINO -DDEVICE_QSPI=1 -DDEVICE_SPI_ASYNCH=1 -DBOARD_PCA10056 -DTARGET_RELEASE -DMBED_MPU_CUSTOM -DMBED_TICKLESS -DTARGET_NRF52840 -DCOMPONENT_QSPIF=1 -DTARGET_MCU_NRF52840 -DDEVICE_PWMOUT=1 -DTARGET_NORDIC -DTARGET_NG_NRF52840_BOOT_DK -DCOMPONENT_NSPE=1 -DTARGET_NRF52840_DK -DTARGET_LIKE_CORTEX_M4 -D__FPU_PRESENT=1 -DARM_MATH_CM4 -DDEVICE_SYSTICK_CLK_OFF_DURING_SLEEP=1 -DDEVICE_INTERRUPTIN=1 -DWSF_MAX_HANDLERS=10 -DDEVICE_PORTINOUT=1 -DTARGET_SOFTDEVICE_NONE -D__CORTEX_M4 -DGPIOTE_CONFIG_NUM_OF_LOW_POWER_EVENTS=8 -DCOMPONENT_PSA_SRV_EMUL=1 -DTARGET_CORTEX_M -DDEVICE_FLASH=1 -DNRF52840_XXAA -DDEVICE_PORTIN=1 -DTOOLCHAIN_GCC -DDEVICE_SERIAL_FC=1 -DDEVICE_I2C_ASYNCH=1 -DDEVICE_ANALOGIN=1 -DCONFIG_GPIO_AS_PINRESET -DDEVICE_ITM=1 -DCMSIS_VECTAB_VIRTUAL -DDEVICE_SERIAL=1 -DCMSIS_VECTAB_VIRTUAL_HEADER_FILE="cmsis_nvic.h" -D__MBED__=1 -DTOOLCHAIN_GCC_ARM -DTARGET_M4 -DDEVICE_SPI=1 -D__CMSIS_RTOS -DDEVICE_PORTOUT=1 -D__MBED_CMSIS_RTOS_CM -DTARGET_NRF5x -DTARGET_LIKE_MBED -DTARGET_CORTEX -DCOMPONENT_PSA_SRV_IMPL=1 -DNRF52_ERRATA_20 -DDEVICE_SERIAL_ASYNCH=1 -DTARGET_RTOS_M4_M7 -DTARGET_NRF52 -DDEVICE_SLEEP=1 -DDEVICE_LPTICKER=1 -DDEVICE_USTICKER=1 -DDEVICE_TRNG=1
Compile [  0.2%]: mbed_tz_context.c

So the next question is, where FileType.LD_SCRIPT is set.

[0xc0170]

LINKER_EXT is used to search for linker script file. mbed_toolchain.py - line 714 should be it - where it gets linker script file and use it for linking.

There might a bug in bare metal configuration - your path looks fine : mbed-os\\targets\\TARGET_NORDIC\\TARGET_NRF5x\\TARGET_NRF52 , cant see why it would remove this target path for bare-metal (it requires platform + drivers, targets should be there by default).

requires is checked in add_config_files method inside config/__init__.py file. Can you check resource objects prior invoking config what is there ? Somewhere your target paths are being removed.

If you have a simple project that we could reproduce, our tools team could have a quick look

[DBS06]

@0xc0170 I added a test repo at https://github.com/DBS06/bare_metal_test
and write also the mbed commands which I used to test into readme.

[DBS06]

@0xc0170 I guess I know why this happens, because '.\\mbed-os\\targets\\TARGET_NORDIC\\TARGET_NRF5x\\TARGET_NRF52' is inside the excluded_lib_paths from mbed-os\tools\resources\__init__.py method: def _include_file(self, ref)

see:

But I don't know why and where it will be added to excluded_lib_paths

[0xc0170]

This is definitely a bug . How did it get to exclude list then?

[DBS06]

@0xc0170 I just made a quick fix inside mbed-os\tools\resources\__init__.py method: def _include_file(self, ref) just to verify if this would be the error/bug:

[...]
        _, path = ref
        cur_dir = dirname(path)
        included_lib_paths = [dirname(e.path) for e in self._libs_filtered]
        excluded_lib_paths = [dirname(e.path) for e in self._excluded_libs]

        nrf52_tool_path = '.\\mbed-os\\targets\\TARGET_NORDIC\\TARGET_NRF5x\\TARGET_NRF52'
        if nrf52_tool_path in excluded_lib_paths:
            excluded_lib_paths.remove(nrf52_tool_path)
[...]

But it is definitely no solution for production usage! 😉
Mhm I am wondering how or from which resources the included- and excluded_lib_paths are generated...

EDIT: with this "fix" (actually you can't call it like that, its more a really really really bad hack) it does compile...

[0xc0170]

cc @ARMmbed/mbed-os-tools

[DBS06]

@ARMmbed/mbed-os-tools @0xc0170
I looked again in this issue, because it seems mbed-os-tools-team does not react.
I think the Linker Script shouldn't be added to all_library_refs in function mbed-os\tools\resources\__init__.py

def filter_by_libraries(self, libraries_included):
        """
        Call after completely done scanning to filter resources based on
        libraries
        """
        self._libs_filtered = set(libraries_included)
        all_library_refs = set(
            ref for ref in self._file_refs[FileType.JSON]
            if ref.name.endswith(MBED_LIB_FILENAME)
        )
        self._excluded_libs = all_library_refs - self._libs_filtered
        if self._collect_ignores:
            self.ignored_dirs += [
                dirname(n) or "." for n, _ in self._excluded_libs
            ]

Because if I build for the EFM32PG12 the Linker script isn't added.

[0xc0170]

@DBS06 tools team was moved recently. To progress here, can you send PR with proposed fix? I'll make sure tools team review , me as well.

[mark-edgeworth]

Yes, thanks for that @0xc0170 :-) We're still coming up-to-speed with all this and are unable to respond to every request as quickly as we'd like at the moment.