defunct: playing around with bootloaders

software/apps/snippets/bootloader/sysbuild/bootloader.overlay

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+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "flash_partitions_128kb.dtsi"
+
+/ {
+	chosen {
+		zephyr,code-partition = &slot0_partition;
+	};
+};

software/apps/snippets/bootloader/sysbuild/flash_partitions_128kb.dtsi

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+/*
+ * Devicetree Overlay for 128KB Flash
+ * - MCUboot Bootloader (32KB)
+ * - Application Slot (96KB)
+ */
+
+&flash0 {
+        /delete-node/ partitions;
+        partitions {
+                compatible = "fixed-partitions";
+                #address-cells = <1>;
+                #size-cells = <1>;
+
+                boot_partition: partition@0 {
+                        label = "mcuboot";
+                        reg = <0x00000000 DT_SIZE_K(32)>;
+                        read-only;
+                };
+
+                slot0_partition: partition@8000 {
+                        label = "image-0";
+                        reg = <0x00008000 DT_SIZE_K(96)>;
+                };
+        };
+};
+
+/* Add retention memory to the existing SRAM node */
+&sram0 {
+        #address-cells = <1>;
+        #size-cells = <1>;
+        
+        retainedmem {
+                compatible = "zephyr,retained-ram";
+                status = "okay";
+                #address-cells = <1>;
+                #size-cells = <1>;
+                
+                boot_mode: retention@7f00 {
+                        compatible = "zephyr,retention";
+                        status = "okay";
+                        reg = <0x7f00 0x100>;
+                        prefix = [08 04];
+                        checksum = <1>;
+                };
+        };
+};
+
+/ {
+        chosen {
+                zephyr,boot-mode = &boot_mode;
+                zephyr,console = &cdc_acm_uart0;
+    };
+};
+
+&zephyr_udc0 {
+    status = "okay";
+    
+    cdc_acm_uart0: cdc_acm_uart0 {
+        compatible = "zephyr,cdc-acm-uart";
+        label = "CDC_ACM_0";
+    };
+};

software/apps/snippets/bootloader/sysbuild/mcuboot.conf

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+#
+# MCUboot Configuration for Serial Recovery over USB-CDC
+#
+
+# Enables serial recovery mode in MCUboot.
+CONFIG_MCUBOOT_SERIAL=y
+
+# Tell MCUboot to check for a trigger to enter recovery
+CONFIG_BOOT_SERIAL_BOOT_MODE=y
+
+# --- USB Stack Configuration ---
+CONFIG_USB_DEVICE_STACK=y
+CONFIG_USB_DEVICE_PRODUCT="MCUboot Serial Recovery"
+
+# Use USB CDC ACM for MCUboot serial recovery (not UART)
+CONFIG_BOOT_SERIAL_CDC_ACM=y
+
+# --- Disable Zephyr Console to avoid conflicts ---
+# MCUboot's serial_adapter doesn't work well with the general console subsystem.
+CONFIG_UART_CONSOLE=n
+CONFIG_CONSOLE_HANDLER=n
+CONFIG_CONSOLE=n
+
+# --- Flash and Stream Configuration (required for IMG_MANAGER) ---
+CONFIG_FLASH=y
+CONFIG_STREAM_FLASH=y
+
+# --- mcumgr Configuration ---
+# MCUMGR requires NET_BUF, even for serial transport.
+CONFIG_NET_BUF=y
+CONFIG_NET_LOG=n
+
+# Enables the mcumgr library and necessary command handlers
+CONFIG_MCUMGR=y
+CONFIG_IMG_MANAGER=y
+CONFIG_MCUMGR_GRP_IMG=y
+CONFIG_MCUMGR_GRP_OS=y
+
+# --- Retention Configuration ---
+CONFIG_RETAINED_MEM=y
+CONFIG_RETENTION=y
+CONFIG_RETENTION_BOOT_MODE=y
+
+# --- Optional: Reduce memory usage ---
+CONFIG_MAIN_STACK_SIZE=2048
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=1024

software/apps/snippets/bootloader/sysbuild/mcuboot.overlay

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+#include "flash_partitions_128kb.dtsi"
+
+/ {
+    chosen {
+        zephyr,code-partition = &boot_partition;
+        zephyr,console = &cdc_acm_uart0;
+    };
+};
+
+&zephyr_udc0 {
+    status = "okay";
+    
+    cdc_acm_uart0: cdc_acm_uart0 {
+        compatible = "zephyr,cdc-acm-uart";
+        label = "CDC_ACM_0";
+    };
+};