Netcore DFU over BLE by using external flash on nRF5340DK. Nordic SDK v2.8.0.

Question

I am evaluating external flash on nRF5340DK. When I'm doing appcore DFU from external flash so that mcuboot_secondary and settings_storage are located on external flash, everything works fine. Now I try to make DFU also for netcore (mcuboot_secondary_1 located on external flash), it fails to error message "Failed to open flash area ID 1: -2". Error message comes from function int img_mgmt_erased_val(int slot, uint8_t *erased_val), located in file v2.8.0/zephyr/subsys/mgmt/mcumgr/grp/img_mgmt/src/zephyr_img_mgmt.c. 
 It tries to open flash area ID #1, but memory area table has only following ID's: 0,2,3,4,5,6,7,8,9,10,12. For some reason ID's 1 and 11 are missing and flash area open fails. I have tried to swap mcuboot_secondary and mcuboot_secondary_1 order in external flash, but netcore DFU (area mcuboot_secodary_1) always fails, physical address does not matter. Is there something wrong in my configuration? pm_static.yml: 
 
 EMPTY_0 : 
 address : 0xfa000 
 end_address : 0xfc000 
 placement : 
 after : 
 - tfm_otp_nv_counters 
 region : flash_primary 
 size : 0x2000 
 EMPTY_1 : 
 address : 0xf6000 
 end_address : 0xf8000 
 placement : 
 after : 
 - tfm_its 
 region : flash_primary 
 size : 0x2000 
 app : 
 address : 0x24000 
 end_address : 0xf4000 
 region : flash_primary 
 size : 0xd0000 
 external_flash : 
 address : 0x130000 
 end_address : 0x800000 
 region : external_flash 
 size : 0x6d0000 
 mcuboot : 
 address : 0x0 
 end_address : 0xc000 
 placement : 
 align : 
 end : 0x1000 
 before : 
 - mcuboot_primary 
 region : flash_primary 
 size : 0xc000 
 mcuboot_pad : 
 address : 0xc000 
 end_address : 0xc200 
 placement : 
 align : 
 start : 0x4000 
 before : 
 - mcuboot_primary_app 
 region : flash_primary 
 size : 0x200 
 mcuboot_primary : 
 address : 0xc000 
 end_address : 0xf4000 
 orig_span : & id001 
 - app 
 - mcuboot_pad 
 - tfm 
 region : flash_primary 
 size : 0xe8000 
 span : * id001 
 mcuboot_primary_1 : 
 address : 0x0 
 device : nordic_ram_flash_controller 
 end_address : 0x40000 
 region : ram_flash 
 size : 0x40000 
 mcuboot_primary_app : 
 address : 0xc200 
 end_address : 0xf4000 
 orig_span : & id002 
 - app 
 - tfm 
 region : flash_primary 
 size : 0xe7e00 
 span : * id002 
 mcuboot_secondary : 
 address : 0x8000 
 device : DT_CHOSEN(nordic_pm_ext_flash) 
 end_address : 0xf0000 
 placement : 
 align : 
 start : 0x4 
 region : external_flash 
 share_size : 
 - mcuboot_primary 
 size : 0xe8000 
 mcuboot_secondary_1 : 
 address : 0xf0000 
 device : DT_CHOSEN(nordic_pm_ext_flash) 
 end_address : 0x130000 
 region : external_flash 
 size : 0x40000 
 mcuboot_sram : 
 address : 0x20000000 
 end_address : 0x20046000 
 orig_span : & id003 
 - pcd_sram 
 - tfm_sram 
 region : sram_primary 
 size : 0x46000 
 span : * id003 
 otp : 
 address : 0xff8100 
 end_address : 0xff83fc 
 region : otp 
 size : 0x2fc 
 pcd_sram : 
 address : 0x20000000 
 end_address : 0x20002000 
 placement : 
 before : 
 - tfm_sram 
 region : sram_primary 
 size : 0x2000 
 ram_flash : 
 address : 0x40000 
 end_address : 0x40000 
 region : ram_flash 
 size : 0x0 
 rpmsg_nrf53_sram : 
 address : 0x20070000 
 end_address : 0x20080000 
 placement : 
 before : 
 - end 
 region : sram_primary 
 size : 0x10000 
 settings_storage : 
 address : 0x0 
 device : DT_CHOSEN(nordic_pm_ext_flash) 
 end_address : 0x8000 
 placement : 
 before : 
 - tfm_storage 
 - end 
 region : external_flash 
 size : 0x8000 
 sram_nonsecure : 
 address : 0x20032000 
 end_address : 0x20080000 
 orig_span : & id004 
 - sram_primary 
 - rpmsg_nrf53_sram 
 region : sram_primary 
 size : 0x4e000 
 span : * id004 
 sram_primary : 
 address : 0x20032000 
 end_address : 0x20070000 
 region : sram_primary 
 size : 0x3e000 
 sram_secure : 
 address : 0x20000000 
 end_address : 0x20032000 
 orig_span : & id005 
 - pcd_sram 
 - tfm_sram 
 region : sram_primary 
 size : 0x32000 
 span : * id005 
 tfm : 
 address : 0xc200 
 end_address : 0x24000 
 inside : 
 - mcuboot_primary_app 
 placement : 
 before : 
 - app 
 region : flash_primary 
 size : 0x17e00 
 tfm_its : 
 address : 0xf4000 
 end_address : 0xf6000 
 inside : 
 - tfm_storage 
 placement : 
 align : 
 start : 0x4000 
 before : 
 - tfm_otp_nv_counters 
 region : flash_primary 
 size : 0x2000 
 tfm_nonsecure : 
 address : 0x24000 
 end_address : 0xf4000 
 orig_span : & id006 
 - app 
 region : flash_primary 
 size : 0xd0000 
 span : * id006 
 tfm_otp_nv_counters : 
 address : 0xf8000 
 end_address : 0xfa000 
 inside : 
 - tfm_storage 
 placement : 
 align : 
 start : 0x4000 
 before : 
 - tfm_ps 
 region : flash_primary 
 size : 0x2000 
 tfm_ps : 
 address : 0xfc000 
 end_address : 0x100000 
 inside : 
 - tfm_storage 
 placement : 
 align : 
 start : 0x4000 
 before : 
 - end 
 region : flash_primary 
 size : 0x4000 
 tfm_secure : 
 address : 0xc000 
 end_address : 0x24000 
 orig_span : & id007 
 - mcuboot_pad 
 - tfm 
 region : flash_primary 
 size : 0x18000 
 span : * id007 
 tfm_sram : 
 address : 0x20002000 
 end_address : 0x20032000 
 inside : 
 - sram_secure 
 placement : 
 after : 
 - start 
 region : sram_primary 
 size : 0x30000 
 tfm_storage : 
 address : 0xf4000 
 end_address : 0x100000 
 orig_span : & id008 
 - tfm_ps 
 - tfm_its 
 - tfm_otp_nv_counters 
 region : flash_primary 
 size : 0xc000 
 span : * id008 
 
 sysbuild.conf: 
 
 # Build MCUboot image 
 SB_CONFIG_BOOTLOADER_MCUBOOT =y 
 # Set MCUboot signature type to ECDSA-P256 
 SB_CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256 =y 
 # Build MCUboot and application in overwrite only mode 
 SB_CONFIG_MCUBOOT_MODE_OVERWRITE_ONLY =y 
 # Places the secondary MCUboot update partition in external flash 
 SB_CONFIG_PM_EXTERNAL_FLASH_MCUBOOT_SECONDARY =y 
 # nRF Connect SDK ipc_radio image 
 SB_CONFIG_NETCORE_IPC_RADIO =y 
 # Enable network core image update support in MCUboot (PCD) 
 SB_CONFIG_NETCORE_APP_UPDATE =y 
 # Enable secure boot for network core 
 SB_CONFIG_SECURE_BOOT_NETCORE =y

prj.conf:

# Enable point to point DFU over SMP 
 CONFIG_BOOTLOADER_MCUBOOT =y 
 CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU =y 
 CONFIG_NCS_SAMPLE_MCUMGR_BT_OTA_DFU_SPEEDUP =y 
 
 # Use the default configuration for NCS samples 
 CONFIG_NCS_SAMPLES_DEFAULTS =y 
 
 # Enable RTT terminal 
 CONFIG_LOG =y 
 CONFIG_STDOUT_CONSOLE =y 
 CONFIG_USE_SEGGER_RTT =y 
 CONFIG_RTT_CONSOLE =y 
 CONFIG_UART_CONSOLE =n 
 
 # General configuration 
 CONFIG_NCS_APPLICATION_BOOT_BANNER_STRING = "Test Name 
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE =2048 
 CONFIG_HWINFO =y 
 CONFIG_DK_LIBRARY =y 
 CONFIG_PM_SINGLE_IMAGE =y 
 CONFIG_SOC_FLASH_NRF_PARTIAL_ERASE =y 
 
 # Use settings on external flash 
 CONFIG_FLASH =y 
 CONFIG_FLASH_MAP =y 
 CONFIG_NVS =y 
 CONFIG_NVS_LOOKUP_CACHE =y 
 CONFIG_SETTINGS =y 
 CONFIG_SETTINGS_NVS_NAME_CACHE =y 
 CONFIG_PM_PARTITION_REGION_SETTINGS_STORAGE_EXTERNAL =y 
 CONFIG_PM_PARTITION_SIZE_SETTINGS_STORAGE =0x8000 
 
 # Bluetooth configuration 
 CONFIG_BT =y 
 CONFIG_BT_DEVICE_NAME = "Test Name" 
 CONFIG_BT_L2CAP_TX_BUF_COUNT =8 
 
 CONFIG_BT_OBSERVER =y 
 CONFIG_BT_PERIPHERAL =y 
 CONFIG_BT_SETTINGS =n 
 
 # Increase RX stack size to avoid overflow during provisioning 
 CONFIG_BT_RX_STACK_SIZE =2700 
 
 # Enable Extended Advertiser to advertise BT SMP service 
 CONFIG_BT_EXT_ADV =y 
 CONFIG_BT_EXT_ADV_MAX_ADV_SET =6 
 
 # One extra connection for mesh GATT/proxy and one for SMP BT. 
 CONFIG_BT_MAX_CONN =3 
 
 # One extra identity for SMP service 
 CONFIG_BT_ID_MAX =2 
 
 # Disable unused Bluetooth features 
 CONFIG_BT_CTLR_LE_ENC =n 
 CONFIG_BT_PHY_UPDATE =n 
 CONFIG_BT_CTLR_CHAN_SEL_2 =n 
 CONFIG_BT_CTLR_MIN_USED_CHAN =n 
 CONFIG_BT_CTLR_PRIVACY =n 
 
 # Bluetooth Mesh configuration 
 CONFIG_BT_MESH =y 
 CONFIG_BT_MESH_RELAY =y 
 CONFIG_BT_MESH_FRIEND =n 
 CONFIG_BT_MESH_TX_SEG_MAX =10 
 CONFIG_BT_MESH_PB_GATT =n 
 CONFIG_BT_MESH_GATT_PROXY =n 
 CONFIG_BT_MESH_PROXY_USE_DEVICE_NAME =n 
 CONFIG_BT_MESH_DK_PROV =y 
 
 app.overlay:

/ { 
 chosen { 
 nordic,pm-ext-flash = & mx25r64 ; 
 }; 
 }; 
 
 sysbuild/mcuboot/prj.conf:

CONFIG_PM =n 
 
 CONFIG_MAIN_STACK_SIZE =10240 
 CONFIG_MBEDTLS_CFG_FILE="mcuboot-mbedtls-cfg.h" 
 
 CONFIG_BOOT_SWAP_SAVE_ENCTLV =n 
 CONFIG_BOOT_ENCRYPT_IMAGE =n 
 
 CONFIG_BOOT_UPGRADE_ONLY =y 
 CONFIG_BOOT_BOOTSTRAP =n 
 
 ### mbedTLS has its own heap 
 # CONFIG_HEAP_MEM_POOL_SIZE is not set 
 
 ### We never want Zephyr's copy of tinycrypt. If tinycrypt is needed, 
 ### MCUboot has its own copy in tree. 
 # CONFIG_TINYCRYPT is not set 
 # CONFIG_TINYCRYPT_ECC_DSA is not set 
 # CONFIG_TINYCRYPT_SHA256 is not set 
 
 CONFIG_FLASH =y 
 CONFIG_FPROTECT =y 
 
 ### Various Zephyr boards enable features that we don't want. 
 # CONFIG_BT is not set 
 # CONFIG_BT_CTLR is not set 
 # CONFIG_I2C is not set 
 
 CONFIG_LOG =y 
 CONFIG_LOG_MODE_MINIMAL =y # former CONFIG_MODE_MINIMAL 
 ### Ensure Zephyr logging changes don't use more resources 
 CONFIG_LOG_DEFAULT_LEVEL =0 
 ### Use info log level by default 
 CONFIG_MCUBOOT_LOG_LEVEL_INF =y 
 ### Decrease footprint by ~4 KB in comparison to CBPRINTF_COMPLETE=y 
 CONFIG_CBPRINTF_NANO =y 
 ### Use the minimal C library to reduce flash usage 
 CONFIG_MINIMAL_LIBC =y 
 CONFIG_NRF_RTC_TIMER_USER_CHAN_COUNT =0 
 
 # NCS boot banner 
 CONFIG_NCS_APPLICATION_BOOT_BANNER_STRING = "MCUboot" 
 
 # Set QSPI flash layout configuration 
 CONFIG_NORDIC_QSPI_NOR_FLASH_LAYOUT_PAGE_SIZE =4096 
 CONFIG_NORDIC_QSPI_NOR_STACK_WRITE_BUFFER_SIZE =16 
 
 CONFIG_BOOT_MAX_IMG_SECTORS =256 
 
 sysbuild/mcuboot/app.overlay:

/ { 
 chosen { 
 nordic,pm-ext-flash = & mx25r64 ; 
 }; 
 };