pbio/sys/storage: Keep user data in same place.

By keeping it in the same place as the releases that introduced these features, we have a simpler upgrade path and better compatability with older versions.

Author: laurensvalk

CHANGELOG.md

@@ -4,6 +4,12 @@
 
 ## [Unreleased]
 
+### Fixed
+- Fixed persistent data not being deleted when swapping
+  from `3.6.0b1` to `3.5.0` and back to `3.6.0b1` ([support#1846]).
+
+[support#1846]: https://github.com/pybricks/support/issues/1846
+
 ## [3.6.0b1] - 2024-09-24
 
 ### Added

lib/pbio/sys/storage.c

@@ -65,17 +65,17 @@ typedef struct {
      */
     volatile uint32_t checksum_complement;
     #endif
+    /**
+     * End-user read-write accessible data. Everything after this is also
+     * user-readable but not writable.
+     */
+    uint8_t user_data[PBSYS_CONFIG_STORAGE_USER_DATA_SIZE];
     /**
      * First 8 symbols of the git hash of the firmware version used to create
      * this data map. If this does not match the version of the running
      * firmware, user data will be reset to 0.
      */
     char stored_firmware_hash[8];
-    /**
-     * End-user read-write accessible data. Everything after this is also
-     * user-readable but not writable.
-     */
-    uint8_t user_data[PBSYS_CONFIG_STORAGE_USER_DATA_SIZE];
     /**
      * System settings. Settings will be reset to defaults when the firmware
      * version changes due to an update.