diff --git a/arm9/Makefile b/arm9/Makefile
index ccf663b..272765a 100644
--- a/arm9/Makefile
+++ b/arm9/Makefile
@@ -159,8 +159,8 @@ $(OUTPUT).elf	:	$(OFILES)
 $(OFILES_SRC)	: $(HFILES_BIN)
 
 memory.o strings.o:	CFLAGS +=	-O3
-config.o:			CFLAGS +=	-DCONFIG_TITLE="\"$(APP_TITLE) $(REVISION) configuration\""
-patches.o:			CFLAGS +=	-DVERSION_MAJOR="$(VERSION_MAJOR)" -DVERSION_MINOR="$(VERSION_MINOR)"\
+patches.o config.o:	CFLAGS +=	-DCONFIG_TITLE="\"$(APP_TITLE) $(REVISION) configuration\""\
+								-DVERSION_MAJOR="$(VERSION_MAJOR)" -DVERSION_MINOR="$(VERSION_MINOR)"\
 								-DVERSION_BUILD="$(VERSION_BUILD)" -DISRELEASE="$(IS_RELEASE)" -DCOMMIT_HASH="0x$(COMMIT)"
 #---------------------------------------------------------------------------------
 # you need a rule like this for each extension you use as binary data
diff --git a/arm9/source/config.c b/arm9/source/config.c
index fcac6c5..d5c8ea9 100644
--- a/arm9/source/config.c
+++ b/arm9/source/config.c
@@ -24,6 +24,7 @@
 *         reasonable ways as different from the original version.
 */
 
+#include <assert.h>
 #include "config.h"
 #include "memory.h"
 #include "fs.h"
@@ -33,26 +34,97 @@
 #include "emunand.h"
 #include "buttons.h"
 #include "pin.h"
+#include "i2c.h"
+
+#define MAKE_LUMA_VERSION_MCU(major, minor, build) (u16)(((major) & 0xFF) << 8 | ((minor) & 0x1F) << 5 | ((build) & 7))
 
 CfgData configData;
 ConfigurationStatus needConfig;
 static CfgData oldConfig;
 
+static CfgDataMcu configDataMcu;
+static_assert(sizeof(CfgDataMcu) > 0, "wrong data size");
+
+static void writeConfigMcu(void)
+{
+    u8 data[sizeof(CfgDataMcu)];
+
+    // Set Luma version
+    configDataMcu.lumaVersion = MAKE_LUMA_VERSION_MCU(VERSION_MAJOR, VERSION_MINOR, VERSION_BUILD);
+
+    // Set bootconfig from CfgData
+    configDataMcu.bootCfg = configData.bootConfig;
+
+    memcpy(data, &configDataMcu, sizeof(CfgDataMcu));
+
+    // Fix checksum
+    u8 checksum = 0;
+    for (u32 i = 0; i < sizeof(CfgDataMcu) - 1; i++)
+        checksum += data[i];
+    checksum = ~checksum;
+    data[sizeof(CfgDataMcu) - 1] = checksum;
+    configDataMcu.checksum = checksum;
+
+    I2C_writeReg(I2C_DEV_MCU, 0x60, 200 - sizeof(CfgDataMcu));
+    I2C_writeRegBuf(I2C_DEV_MCU, 0x61, data, sizeof(CfgDataMcu));
+}
+
+static bool readConfigMcu(void)
+{
+    u8 data[sizeof(CfgDataMcu)];
+    u16 curVer = MAKE_LUMA_VERSION_MCU(VERSION_MAJOR, VERSION_MINOR, VERSION_BUILD);
+
+    // Select free reg id, then access the data regs
+    I2C_writeReg(I2C_DEV_MCU, 0x60, 200 - sizeof(CfgDataMcu));
+    I2C_readRegBuf(I2C_DEV_MCU, 0x61, data, sizeof(CfgDataMcu));
+    memcpy(&configDataMcu, data, sizeof(CfgDataMcu));
+
+    u8 checksum = 0;
+    for (u32 i = 0; i < sizeof(CfgDataMcu) - 1; i++)
+        checksum += data[i];
+    checksum = ~checksum;
+
+    if (checksum != configDataMcu.checksum || configDataMcu.lumaVersion < MAKE_LUMA_VERSION_MCU(10, 3, 0))
+    {
+        // Invalid data stored in MCU...
+        configData.bootConfig = 0;
+        // Perform upgrade process (ignoring failures)
+        doLumaUpgradeProcess();
+        writeConfigMcu();
+
+        return false;
+    }
+
+    if (configDataMcu.lumaVersion < curVer)
+    {
+        // Perform upgrade process (ignoring failures)
+        doLumaUpgradeProcess();
+        writeConfigMcu();
+    }
+
+    return true;
+}
+
 bool readConfig(void)
 {
     bool ret;
 
+    ret = readConfigMcu();
+    if (!ret)
+        return false;
+
     if(fileRead(&configData, CONFIG_FILE, sizeof(CfgData)) != sizeof(CfgData) ||
        memcmp(configData.magic, "CONF", 4) != 0 ||
        configData.formatVersionMajor != CONFIG_VERSIONMAJOR ||
        configData.formatVersionMinor != CONFIG_VERSIONMINOR)
     {
         memset(&configData, 0, sizeof(CfgData));
-
         ret = false;
     }
-    else ret = true;
+    else
+        ret = true;
 
+    configData.bootConfig = configDataMcu.bootCfg;
     oldConfig = configData;
 
     return ret;
@@ -73,7 +145,9 @@ void writeConfig(bool isConfigOptions)
         needConfig = MODIFY_CONFIGURATION;
     }
 
-    if(!fileWrite(&configData, CONFIG_FILE, sizeof(CfgData)))
+    if (!isConfigOptions)
+        writeConfigMcu();
+    else if(!fileWrite(&configData, CONFIG_FILE, sizeof(CfgData)))
         error("Error writing the configuration file");
 }
 
diff --git a/arm9/source/config.h b/arm9/source/config.h
index de81062..6b00bc1 100644
--- a/arm9/source/config.h
+++ b/arm9/source/config.h
@@ -34,7 +34,7 @@
 
 #define CONFIG_FILE         "config.bin"
 #define CONFIG_VERSIONMAJOR 2
-#define CONFIG_VERSIONMINOR 4
+#define CONFIG_VERSIONMINOR 5
 
 #define BOOTCFG_NAND         BOOTCONFIG(0, 7)
 #define BOOTCFG_FIRM         BOOTCONFIG(3, 7)
diff --git a/arm9/source/fs.c b/arm9/source/fs.c
index 300a59f..30c4422 100644
--- a/arm9/source/fs.c
+++ b/arm9/source/fs.c
@@ -60,8 +60,19 @@ static bool switchToMainDir(bool isSd)
 
 bool mountFs(bool isSd, bool switchToCtrNand)
 {
-    return isSd ? f_mount(&sdFs, "0:", 1) == FR_OK && switchToMainDir(true) :
-                  f_mount(&nandFs, "1:", 1) == FR_OK && (!switchToCtrNand || (f_chdrive("1:") == FR_OK && switchToMainDir(false)));
+    static bool sdInitialized = false, nandInitialized = false;
+    if (isSd)
+    {
+        if (!sdInitialized)
+            sdInitialized = f_mount(&sdFs, "0:", 1) == FR_OK;
+        return sdInitialized && switchToMainDir(true);
+    }
+    else
+    {
+        if (!nandInitialized)
+            nandInitialized = f_mount(&nandFs, "1:", 1) == FR_OK;
+        return nandInitialized && (!switchToCtrNand || (f_chdrive("1:") == FR_OK && switchToMainDir(false)));
+    }
 }
 
 u32 fileRead(void *dest, const char *path, u32 maxSize)
@@ -385,8 +396,9 @@ void findDumpFile(const char *folderPath, char *fileName)
     if(result == FR_OK) f_closedir(&dir);
 }
 
-static u8 fileCopyBuffer[0x1000];
-bool backupEssentialFiles(void)
+static u8 fileCopyBuffer[0x10000];
+
+static bool backupEssentialFiles(void)
 {
     size_t sz = sizeof(fileCopyBuffer);
 
@@ -420,3 +432,20 @@ bool backupEssentialFiles(void)
 
     return ok;
 }
+
+bool doLumaUpgradeProcess(void)
+{
+    // Ensure CTRNAND is mounted
+    bool ok = mountFs(false, false), ok2 = true;
+    if (!ok)
+        return false;
+
+    // Try to boot.firm to CTRNAND, when applicable
+    if (isSdMode)
+        ok = fileCopy("0:/boot.firm", "1:/boot.firm", true, fileCopyBuffer, sizeof(fileCopyBuffer));
+
+    // Try to backup essential files
+    ok2 = backupEssentialFiles();
+
+    return ok && ok2;
+}
diff --git a/arm9/source/fs.h b/arm9/source/fs.h
index 99c5a9c..477432c 100644
--- a/arm9/source/fs.h
+++ b/arm9/source/fs.h
@@ -41,4 +41,4 @@ bool payloadMenu(char *path, bool *hasDisplayedMenu);
 u32 firmRead(void *dest, u32 firmType);
 void findDumpFile(const char *folderPath, char *fileName);
 
-bool backupEssentialFiles(void);
+bool doLumaUpgradeProcess(void);
diff --git a/arm9/source/types.h b/arm9/source/types.h
index 871bb45..cba2d10 100644
--- a/arm9/source/types.h
+++ b/arm9/source/types.h
@@ -71,6 +71,14 @@ typedef struct __attribute__((packed, aligned(4)))
     u32 rosalinaMenuCombo;
 } CfgData;
 
+typedef struct
+{
+    u16 lumaVersion;
+    u8 bootCfg;
+    u8 reserved[2];
+    u8 checksum;
+} CfgDataMcu;
+
 typedef struct
 {
     char magic[4];