NCS v3.4.0 (DTS-based partitioning): How to place MCUboot secondary slot in external flash without Partition Manager?

[Yoshihiro Goto]

Hi,

I am using NCS v3.4.0 with the following setup:

• Board: nrf7002dk/nrf5340/cpuapp/ns
• SDK version: NCS v3.4.0

I have two related questions:

---

Issue 1: MCUboot secondary slot in external flash without Partition Manager

Since NCS v3.4.0 deprecates Partition Manager in favor of DTS-based partitioning, I am trying to migrate my project accordingly.

However, I need to place the MCUboot secondary slot in external flash, and the Kconfig option SB_CONFIG_PM_EXTERNAL_FLASH_MCUBOOT_SECONDARY=y depends on PARTITION_MANAGER, so it cannot be used without Partition Manager:

SB_CONFIG_PM_EXTERNAL_FLASH_MCUBOOT_SECONDARY was assigned the value y, but got the value n. Missing dependencies: PARTITION_MANAGER

Could you please tell me how to place the MCUboot secondary slot in external flash using DTS-based partitioning instead of Partition Manager?

---

Issue 2: Memory Report Partitions tab missing in VS Code

Since migrating to DTS-based partitioning in NCS v3.4.0, the Partitions tab is no longer shown in the nRF Connect for VS Code Memory Report.

I have confirmed that:

• partitions.yml is not generated in the build directory
• Running west build -t partition_manager_report results in:

  ninja: error: unknown target 'partition_manager_report'

This confirms that Partition Manager is completely disabled in my project. Is the Partitions tab in Memory Report planned to be updated to support DTS-based partitioning?

---

Thank you!

[AHaug]

Hi,

In the migration notes there are some helpful tools that can convert an existing partition-manager project into a dts based project: https://nrfconnectdocs.nordicsemi.com/ncs/latest/nrf/releases_and_maturity/migration/migration_partitions.html#migrate-your-project-to-dts-partitioning 

Could you please tell me how to place the MCUboot secondary slot in external flash using DTS-based partitioning instead of Partition Manager?

Here's a sample dts from the nrf for desktop sample that shows how to configure the internal and external flash in DTS

/* In your board overlay or memory_map.dtsi */

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

/* Internal flash partitions */
&flash0 {
    partitions {
        compatible = "fixed-partitions";
        #address-cells = <1>;
        #size-cells = <1>;

        boot_partition: partition@0 {
            label = "mcuboot";
            reg = <0x00000000 0x0000c000>;
        };

        slot0_partition: partition@c000 {
            label = "image-0";
            reg = <0x0000c000 0x00076000>;
        };

        storage_partition: partition@f8000 {
            label = "storage";
            reg = <0x000f8000 0x00008000>;
        };
    };
};

/* External flash: secondary slot placed here */
&mx25r64 {
    status = "okay";

    partitions {
        compatible = "fixed-partitions";
        #address-cells = <1>;
        #size-cells = <1>;

        slot1_partition: partition@0 {
            label = "image-1";
            reg = <0x00000000 0x00076000>; /* same size as slot0 */
        };
    };
};

Is the Partitions tab in Memory Report planned to be updated to support DTS-based partitioning?

I will check with the VS Code team to verify.

Kind regards,
Andreas

[Yoshihiro Goto]

Hi,

I tried to migrate to DTS-based partitioning following the migration guide, but I was unable to get it working. I'm sharing what I found during the investigation, hoping to get some guidance.

Environment:

• NCS v3.4.0
• nRF7002DK
• MCUboot + DTS-based partitioning (without Partition Manager)
• Wi-Fi patches in external flash (mx25r64)

What I found:

1. I had the nrf70-fw-patch-ext-flash snippet enabled in my build configuration. This snippet applies fw-patch-ext-flash.overlay, which defines nrf70_wifi_fw_partition at partition@0 in mx25r64. This conflicted with my own overlay where I was also trying to define nrf70_wifi_fw_partition, causing a duplicate label error. Removing the snippet resolved this conflict.

2. After removing the snippet, I added the partition definitions to both the application overlay and the MCUboot overlay. However, I still get the following build error:

```

C:/ncs/v3.4.0/bootloader/mcuboot/boot/zephyr/include/sysflash/sysflash.h: In function '__flash_area_ids_for_slot':
C:/ncs/v3.4.0/zephyr/include/zephyr/devicetree.h:197:36: error: 'DT_N_NODELABEL_slot2_partition_PARTITION_ID' undeclared (first use in this function); did you mean 'DT_N_NODELABEL_slot1_partition'?
C:/ncs/v3.4.0/zephyr/include/zephyr/devicetree.h:197:36: error: 'DT_N_NODELABEL_slot3_partition_PARTITION_ID' undeclared (first use in this function); did you mean 'DT_N_NODELABEL_slot1_partition'?

```

My current application overlay:

/delete-node/ &slot0_partition;
/delete-node/ &slot1_partition;
/delete-node/ &storage_partition;

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

&flash0 {
	partitions {
		boot_partition: partition@0 {
			compatible = "zephyr,mapped-partition";
			label = "mcuboot";
			reg = <0x0 0x10000>;
		};

		slot0_partition: partition@10000 {
			compatible = "zephyr,mapped-partition";
			label = "image-0";
			reg = <0x10000 0xec000>;
		};

		storage_partition: partition@fc000 {
			compatible = "zephyr,mapped-partition";
			label = "storage";
			reg = <0xfc000 0x2000>;
		};
	};
};

&mx25r64 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		nrf70_wifi_fw_partition: nrf70_fw_partition: slot2_partition: partition@0 {
			label = "image-2";
			reg = <0x0 0x20000>;
		};

		slot1_partition: partition@20000 {
			label = "image-1";
			reg = <0x20000 0xec000>;
		};

		slot3_partition: partition@10c000 {
			label = "image-3";
			reg = <0x10c000 0x20000>;
		};
	};
};

My current MCUboot overlay:

/ {
	chosen {
		nordic,pm-ext-flash = &mx25r64;
		zephyr,code-partition = &boot_partition;
	};
};

&flash0 {
	partitions {
		boot_partition: partition@0 {
			compatible = "zephyr,mapped-partition";
			label = "mcuboot";
			reg = <0x0 0x10000>;
		};

		slot0_partition: partition@10000 {
			compatible = "zephyr,mapped-partition";
			label = "image-0";
			reg = <0x10000 0xec000>;
		};

		storage_partition: partition@fc000 {
			compatible = "zephyr,mapped-partition";
			label = "storage";
			reg = <0xfc000 0x2000>;
		};
	};
};

&mx25r64 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		nrf70_wifi_fw_partition: nrf70_fw_partition: slot2_partition: partition@0 {
			label = "image-2";
			reg = <0x0 0x20000>;
		};

		slot1_partition: partition@20000 {
			label = "image-1";
			reg = <0x20000 0xec000>;
		};

		slot3_partition: partition@10c000 {
			label = "image-3";
			reg = <0x10c000 0x20000>;
		};
	};
};

For now, I have decided to stay with PM-based partitioning since I am using v3.4.0 LTS and need to move forward with a new project. However, I would appreciate any guidance on the correct approach for DTS-based partitioning with external flash on nRF7002DK.

Thank you!

[AHaug]

Hi Yoshihara,

I will have a closer look at it today and see if I can provide a better reference. To expand a bit, which are you looking for:

1. A sample showing the dts based partitioning in NCS v3.4.0
2. How to port an application from 3.3.0 with partition manager into 3.4.0 with dts partitioning?

Kind regards,
Andreas