EFR32BG22: Memory regions must have a non-zero length

[drt1245]

I am trying to use PyOCD with an EFR32BG22C224F512GM32 Bluetooth microcontroller. To install the pack, I ran the command pyocd pack install EFR32BG22C224F512GM32, which installed SiliconLabs.GeckoPlatform_EFR32BG22_DFP.2025.6.2

Running PyOCD with this target gives a memory region error:

$ pyocd gdbserver --verbose --target=EFR32BG22C224F512GM32
0000337 D [Errno 13] Access denied (insufficient permissions) while trying to interrogate a USB device (VID=0424 PID=2740). This can probably be remedied with a udev rule. See <https://github.com/pyocd/pyOCD/tree/master/udev> for help. [pyusb_backend]
0000352 D [Errno 13] Access denied (insufficient permissions) while trying to interrogate a USB device (VID=0424 PID=2740). This can probably be remedied with a udev rule. See <https://github.com/pyocd/pyOCD/tree/master/udev> for help. [pyusb_v2_backend]
0000352 D Project directory: /home/dtarry [session]
0000353 D Project directory: /home/dtarry [session]
0000367 D CMSIS-DAP v2 probe E66138528353692B: protocol version 2.0.0 [dap_access_cmsis_dap]
0000600 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000600 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000600 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000601 D GeckoPlatform_EFR32BG22_DFP DFP: skipping non-Keil flash algorithm [cmsis_pack]
0000623 C Error: Memory regions must have a non-zero length. [__main__]
Traceback (most recent call last):
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/__main__.py", line 161, in run
    status = cmd.invoke()
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/subcommands/gdbserver_cmd.py", line 182, in invoke
    session = Session(probe_proxy,
        project_dir=self._args.project_dir,
    ...<10 lines>...
        option_defaults=self._modified_option_defaults(),
    )
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/core/session.py", line 231, in __init__
    self._board = probe.create_associated_board() or Board(self)
                                                     ~~~~~^^^^^^
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/board/board.py", line 125, in __init__
    self.target = TARGET[self._target_type](session)
                  ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/target/pack/pack_target.py", line 383, in _pack_target__init__
    super(self.__class__, self).__init__(session, self._pack_device.memory_map)
                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/target/pack/cmsis_pack.py", line 1010, in memory_map
    self._build_memory_regions()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/target/pack/cmsis_pack.py", line 769, in _build_memory_regions
    region = MEMORY_TYPE_CLASS_MAP[type](**attrs)
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/core/memory_map.py", line 496, in __init__
    super().__init__(start=start, end=end, length=length, **attrs)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dtarry/pyocd/lib/python3.13/site-packages/pyocd/core/memory_map.py", line 289, in __init__
    assert self.length > 0, "Memory regions must have a non-zero length."
           ^^^^^^^^^^^^^^^
AssertionError: Memory regions must have a non-zero length.

Running without the target specified (for generic Cortex-M) works (I can read from memory), but I can't program that way.

$ pyocd gdbserver
0000377 W Generic 'cortex_m' target type is selected by default; is this intentional? You will be able to debug most devices, but not program flash. To set the target type use the '--target' argument or 'target_override' option. Use 'pyocd list --targets' to see available targets types. [board]
0000377 I Target type is cortex_m [board]
0000394 I DP IDR = 0x6ba02477 (v2 rev6) [dap]
0000400 I AHB-AP#0 IDR = 0x84770001 (AHB-AP var0 rev8) [discovery]
0000403 I APB-AP#1 IDR = 0x54770002 (APB-AP var0 rev5) [discovery]
0000405 I AHB-AP#3 IDR = 0x84770001 (AHB-AP var0 rev8) [discovery]
0000409 I AHB-AP#0 Class 0x1 ROM table #0 @ 0xe00fe000 (designer=673 part=d41) [rom_table]
0000411 I [0]<e00ff000:ROM class=1 designer=43b:Arm part=4c9> [rom_table]
0000411 I   AHB-AP#0 Class 0x1 ROM table #1 @ 0xe00ff000 (designer=43b:Arm part=4c9) [rom_table]
0000414 I   [0]<e000e000:SCS M33 class=9 designer=43b:Arm part=d21 devtype=00 archid=2a04 devid=0:0:0> [rom_table]
0000416 I   [1]<e0001000:DWT M33 class=9 designer=43b:Arm part=d21 devtype=00 archid=1a02 devid=0:0:0> [rom_table]
0000418 I   [2]<e0002000:BPU M33 class=9 designer=43b:Arm part=d21 devtype=00 archid=1a03 devid=0:0:0> [rom_table]
0000420 I   [3]<e0000000:ITM M33 class=9 designer=43b:Arm part=d21 devtype=43 archid=1a01 devid=0:0:0> [rom_table]
0000422 I   [5]<e0041000:ETM M33 class=9 designer=43b:Arm part=d21 devtype=13 archid=4a13 devid=0:0:0> [rom_table]
0000423 I   [6]<e0042000:CTI M33 class=9 designer=43b:Arm part=d21 devtype=14 archid=1a14 devid=40800:0:0> [rom_table]
0000425 I [1]<e0040000:TPIU M33 class=9 designer=43b:Arm part=d21 devtype=11 archid=0000 devid=ca1:0:0> [rom_table]
0000427 I [2]<e00fd000:TSGEN class=15 designer=43b:Arm part=101> [rom_table]
0000429 I APB-AP#1 Class 0x1 ROM table #0 @ 0x000000 (designer=673 part=db6) [rom_table]
0000431 I [0]<00001000:??? class=15 designer=673 part=051> [rom_table]
0000434 I AHB-AP#3 Class 0x1 ROM table #0 @ 0xf0000000 (designer=673 part=52d) [rom_table]
0000437 I [0]<e00ff000:ROM class=1 designer=43b:Arm part=4c0> [rom_table]
0000437 I   AHB-AP#3 Class 0x1 ROM table #1 @ 0xe00ff000 (designer=43b:Arm part=4c0) [rom_table]
0000439 I   [0]<e000e000:SCS v6-M class=14 designer=43b:Arm part=008> [rom_table]
0000440 I   [1]<e0001000:DWT v6-M class=14 designer=43b:Arm part=00a> [rom_table]
0000442 I   [2]<e0002000:BPU v6-M class=14 designer=43b:Arm part=00b> [rom_table]
0000444 I [1]<f0001000:CTI M0+ class=9 designer=43b:Arm part=9a6 devtype=14 archid=1a14 devid=1040800:0:0> [rom_table]
0000450 I CPU core #0: Cortex-M33 r0p4, v8.0-M architecture [cortex_m]
0000450 I   Extensions: [DSP, FPU, FPU_V5, MPU, SEC] [cortex_m]
0000450 I   FPU present: FPv5-SP-D16-M [cortex_m]
0000453 I CPU core #1: Cortex-M0+ r0p1, v6.0-M architecture [cortex_m]
0000455 I 4 hardware watchpoints [dwt]
0000457 I 8 hardware breakpoints, 1 literal comparators [fpb]
0000461 I 2 hardware watchpoints [dwt]
0000462 I 4 hardware breakpoints, 0 literal comparators [fpb]
0000467 I Semihost server started on port 4444 (core 0) [server]
0000510 I GDB server listening on port 3333 (core 0) [gdbserver]
0000512 I Semihost server started on port 4445 (core 1) [server]
0000513 I GDB server listening on port 3334 (core 1) [gdbserver]

[hagibr]

My suggestion today is to not use these broken CMSIS-Packs and use a built-in target, but do not need to modify anything inside pyocd's files.

This is my pyocd_user.py file that I put at the same folder of my project (-j ), the target is from a similar family (so I don't guarantee compatibility). It was generated from an older CMSIS-Pack, and now I don't need to specify any target, it will default to cortex_m but be replaced right at the beginning and it allows flash writing. I've tested it from pyocd==0.36.0 until pyocd==0.41.0. Flash programming only worked from 0.36.0 ~ 0.39.0, newer versions have some regression:

from pyocd.coresight.coresight_target import CoreSightTarget
from pyocd.core.memory_map import (FlashRegion, RamRegion, MemoryMap)
from pyocd.debug.svd.loader import SVDFile

# FLASH_ALGO initially generated by using scripts/generate_flash_algo.py GECKOS2C3.FLM
# GECKOS2C3.FLM was extracted from CMSIS-Pack, and we did some modifications
FLASH_ALGO = {
    'load_address' : 0x20000000,

    # Flash algorithm as a hex string
    'instructions': [
    0xe7fdbe00,
    0x6801480d, 0x117cf401, 0x1fb0f5b1, 0x490bd904, 0xf442680a, 0x600a3280, 0xf6414909, 0x600a3271,
    0x604a2200, 0x49076880, 0x2180ea01, 0x20004a06, 0x1002f849, 0xbf004770, 0x0fe08004, 0x40008068,
    0x4003003c, 0x03fffc00, 0x00000004, 0xf6414905, 0x60083071, 0x22014804, 0x22006002, 0x600a2000,
    0xbf004770, 0x4003003c, 0x4003200c, 0x4d09b5b0, 0xf8592400, 0x42840005, 0x2000bf24, 0x4620bdb0,
    0xf80af000, 0xf5042800, 0xbf1c5400, 0xbdb02001, 0xbf00e7ef, 0x00000004, 0x4602490f, 0x3301ca08,
    0x2900d103, 0x0104f101, 0xb193d1f8, 0x4c0bb5b0, 0x490b2501, 0x60486025, 0x60082002, 0x21002001,
    0xf85ef000, 0x5180f44f, 0x50652800, 0x2001bf18, 0x2000bdb0, 0xbf004770, 0xffffe004, 0x4003100c,
    0x40030010, 0x4df0e92d, 0x1cc84605, 0x4a224692, 0xf0204f22, 0x20010403, 0xe02e6010, 0x5000f505,
    0xeba04388, 0x1e690b05, 0xeba1455c, 0xea6f0000, 0xbf380104, 0x46d046a3, 0x607d4288, 0x4601bf88,
    0xf8d81d4e, 0x2e000000, 0xd00a60b8, 0x21082008, 0x0804f108, 0xf824f000, 0xf1062800, 0xd0f00604,
    0x2004e016, 0x20016038, 0x26012100, 0xf818f000, 0x44dab978, 0xeba4445d, 0xf641040b, 0x2c0071ff,
    0xf44fd1cc, 0x21015080, 0x26004a03, 0xe0005011, 0x46302601, 0x8df0e8bd, 0x4003100c, 0x40030010,
    0x4e10b570, 0x4c0e4a0d, 0xe0091d33, 0x428d4005, 0x2000bf04, 0x3401bd70, 0xf06fbf04, 0xbd700002,
    0x421d6915, 0x6810d0f2, 0xf0204235, 0xf06f0101, 0xbf080001, 0x30fff04f, 0xbd706011, 0x4003000c,
    0xff676980, 0x00010002, 0x00000000, 0x00000000
    ],

    # Relative function addresses
    'pc_init': 0x20000005,
    'pc_unInit': 0x20000051,
    'pc_program_page': 0x200000e9,
    'pc_erase_sector': 0x2000009d,
    #'pc_eraseAll': 0x20000071, # Main modification: the code from CMSIS-Pack doesn't work. By commenting this, pyocd will call pc_erase_sector multiple times instead

    'static_base' : 0x20000000 + 0x00000004 + 0x000001c8,
    'begin_stack' : 0x200071e0,
    'end_stack' : 0x200061e0,
    'begin_data' : 0x20000000 + 0x1000,
    'page_size' : 0x3000,
    'analyzer_supported' : False,
    'analyzer_address' : 0x00000000,
    # Enable double buffering.
    'page_buffers' : [
        0x200001e0,
        0x200031e0
    ],
    'min_program_length' : 0x3000,

    # Relative region addresses and sizes
    'ro_start': 0x4,
    'ro_size': 0x1c8,
    'rw_start': 0x1cc,
    'rw_size': 0x4,
    'zi_start': 0x1d0,
    'zi_size': 0x4,

    # Flash information
    'flash_start': 0x8000000,
    'flash_size': 0x180000,
    'sector_sizes': (
        (0x0, 0x2000),
    )
}


class EFR32BG24(CoreSightTarget):

    VENDOR = "Silicon Labs"

    MEMORY_MAP = MemoryMap(
        FlashRegion(name='Flash', start=0x08000000, length=0x100000, blocksize=0x2000, is_boot_memory=True, algo=FLASH_ALGO),
        RamRegion(name='RAM', start=0x20000000, length=0x20000),
        )

    def __init__(self, session):
        super(EFR32BG24, self).__init__(session, self.MEMORY_MAP)

    
def will_connect(board):
    """@brief Pre-init hook for the board.
    @param self
    @param board A Board instance that is about to be initialized.
    @return Ignored.
    """
    print(f"\n--- WILL_CONNECT Hook Changing target ---")
    board.target = EFR32BG24(board.session)
    pass

[hagibr]

I've tried to generate a pyocd_user.py file using GECKOS2.FLM inside SiliconLabs.GeckoPlatform_EFR32BG22_DFP.2025.6.2.pack. Can you try it and give a feedback?

FLASH_ALGO = {
    'load_address' : 0x20000000,

    # Flash algorithm as a hex string
    'instructions': [
    0xe7fdbe00,
    0x6801480d, 0x117cf401, 0x1fb0f5b1, 0x490bd104, 0xf442680a, 0x600a3200, 0xf6414909, 0x600a3271,
    0x604a2200, 0x49076880, 0x2180ea01, 0x20004a06, 0x1002f849, 0xbf004770, 0x0fe08004, 0x40008068,
    0x4003003c, 0x03fffc00, 0x00000004, 0xf6414905, 0x60083071, 0x22014804, 0x22006002, 0x600a2000,
    0xbf004770, 0x4003003c, 0x4003200c, 0x4d09b5b0, 0xf8592400, 0x42840005, 0x2000bf24, 0x4620bdb0,
    0xf80af000, 0xf5042800, 0xbf1c5400, 0xbdb02001, 0xbf00e7ef, 0x00000004, 0x4602490f, 0x3301ca08,
    0x2900d103, 0x0104f101, 0xb193d1f8, 0x4c0bb5b0, 0x490b2501, 0x60486025, 0x60082002, 0x21002001,
    0xf85ef000, 0x5180f44f, 0x50652800, 0x2001bf18, 0x2000bdb0, 0xbf004770, 0xffffe004, 0x4003100c,
    0x40030010, 0x4df0e92d, 0x1cc84605, 0x4a224692, 0xf0204f22, 0x20010403, 0xe02e6010, 0x5000f505,
    0xeba04388, 0x1e690b05, 0xeba1455c, 0xea6f0000, 0xbf380104, 0x46d046a3, 0x607d4288, 0x4601bf88,
    0xf8d81d4e, 0x2e000000, 0xd00a60b8, 0x21082008, 0x0804f108, 0xf824f000, 0xf1062800, 0xd0f00604,
    0x2004e016, 0x20016038, 0x26012100, 0xf818f000, 0x44dab978, 0xeba4445d, 0xf641040b, 0x2c0071ff,
    0xf44fd1cc, 0x21015080, 0x26004a03, 0xe0005011, 0x46302601, 0x8df0e8bd, 0x4003100c, 0x40030010,
    0x4e10b570, 0x4c0e4a0d, 0xe0091d33, 0x428d4005, 0x2000bf04, 0x3401bd70, 0xf06fbf04, 0xbd700002,
    0x421d6915, 0x6810d0f2, 0xf0204235, 0xf06f0101, 0xbf080001, 0x30fff04f, 0xbd706011, 0x4003000c,
    0xff676980, 0x00010002, 0x00000000, 0x00000000
    ],

    # Relative function addresses
    'pc_init': 0x20000005,
    'pc_unInit': 0x20000051,
    'pc_program_page': 0x200000e9,
    'pc_erase_sector': 0x2000009d,
    #'pc_eraseAll': 0x20000071, # By commenting this, pyocd will call pc_erase_sector multiple times

    'static_base' : 0x20000000 + 0x00000004 + 0x000001c8,
    'begin_stack' : 0x200051e0,
    'end_stack' : 0x200041e0,
    'begin_data' : 0x20000000 + 0x1000,
    'page_size' : 0x2000,
    'analyzer_supported' : False,
    'analyzer_address' : 0x00000000,
    # Enable double buffering
    'page_buffers' : [
        0x200001e0,
        0x200021e0
    ],
    'min_program_length' : 0x2000,

    # Relative region addresses and sizes
    'ro_start': 0x4,
    'ro_size': 0x1c8,
    'rw_start': 0x1cc,
    'rw_size': 0x4,
    'zi_start': 0x1d0,
    'zi_size': 0x4,

    # Flash information
    'flash_start': 0x0000000,
    'flash_size': 0x80000,
    'sector_sizes': (
        (0x0, 0x2000),
    )
}

class EFR32BG22(CoreSightTarget):

    VENDOR = "Silicon Labs"

    MEMORY_MAP = MemoryMap(
        FlashRegion(name='Flash', start=0x00000000, length=0x80000, blocksize=0x2000, is_boot_memory=True, algo=FLASH_ALGO),
        RamRegion(name='RAM', start=0x20000000, length=0x8000),
        )

    def __init__(self, session):
        super(EFR32BG22, self).__init__(session, self.MEMORY_MAP)

def will_connect(board):
    """@brief Pre-init hook for the board.
    @param self
    @param board A Board instance that is about to be initialized.
    @return Ignored.
    """
    print(f"\n--- WILL_CONNECT Hook Changing target ---")
    board.target = EFR32BG22(board.session)
    pass