diff --git a/Firmware/xflash_layout.h b/Firmware/xflash_layout.h
index 5d92d6e6c..48d947f69 100644
--- a/Firmware/xflash_layout.h
+++ b/Firmware/xflash_layout.h
@@ -1,3 +1,50 @@
+
+/**
+ * @file
+ * @author leptun
+ */
+ /** \ingroup xflash_layout */
+ 
+ //! This is the layout of the XFLASH (external SPI flash) in Prusa firmware (dynamically generated from doxygen).
+
+
+/** @defgroup xflash_layout XFLASH Layout
+ *  
+ 
+  ---------------------------------------------------------------------------------
+  The XFLASH has the following alignment requirements:
+   - Block erase of 64KB. This is what the second bootloader uses. If anything even starts writing to a block, the entire block is erased by the bootloader. It will cause loss of crash dump on firmware upload. Nothing more than that.
+   - Block erase of 32KB. Not used.
+   - Sector erase of 4KB. Used by the xflash_dump. This is the minimum size for erasing and as such the dump is 4KB aligned as to not erase other stuff unintentionally.
+   - Page write of 256B. Lower access can be used, but care must be used since the address wraps at the page boundary when writing.
+   - Read has no alignment requirements.
+  
+  The following items are found in the xflash:
+  
+  ### 1. Languages (R)
+    This is a variable size region that is built by the lang build scripts. More info can be found in those scripts.
+    
+    It is aligned at the beginning of xflash, offset 0.
+
+  ### 2. MMU Firmware update files (64KB, R)
+    This space is reserved for the two MMU firmware files:
+     - The MMU firmware v2.0.0+.
+     - The Bootloader self update file.
+   
+   It is aligned at the end of xflash, before xflash_dump
+
+  ### 3. xflash_dump (12KB, RW)
+    The crash dump structure is defined as dump_t.
+    It composes of:
+     - A header with some information such as crash reason and what info was dumped.
+     - The dump itself. This is composed of the entire memory space from address 0 to the end of SRAM. So it includes also the registers (useless), the IO and extended IO (useful) and all RAM.
+    
+    Even though the dump needs around 9KB of storage, 12KB is used because of the sector erase size.
+    
+    It is aligned at the end of xflash.
+*/
+
+
 // XFLASH memory layout
 #pragma once
 #include <stdint.h>
@@ -5,11 +52,6 @@
 #include "config.h"
 
 #define XFLASH_SIZE 0x40000ul // size of XFLASH
-#define LANG_OFFSET 0x0       // offset for language data
-
-#ifndef XFLASH_DUMP
-#define LANG_SIZE   XFLASH_SIZE
-#else
 
 #define DUMP_MAGIC  0x55525547ul
 
@@ -42,10 +84,10 @@ struct dump_t
     struct dump_data_t __attribute__((aligned(256))) data;
 };
 
-// dump offset must be aligned to lower 4kb sector boundary
-#define DUMP_OFFSET ((XFLASH_SIZE - sizeof(dump_t)) & ~0xFFFul)
+#define DUMP_OFFSET ((XFLASH_SIZE - sizeof(dump_t)) & ~0xFFFul) // dump offset must be aligned to lower 4kb sector boundary
+#define MMU_BOOTLOADER_UPDATE_OFFSET (DUMP_OFFSET - 32768) // 32KB of MMU bootloader self update.
+#define MMU_FW_UPDATE_OFFSET (MMU_BOOTLOADER_UPDATE_OFFSET - 32768) // 32KB of MMU fw.
+#define LANG_OFFSET 0x0 // offset for language data
 
-#define DUMP_SIZE   (XFLASH_SIZE - DUMP_OFFSET) // effective dump size area
-#define LANG_SIZE   DUMP_OFFSET                 // available language space
-
-#endif
+#define LANG_SIZE (MMU_FW_UPDATE_OFFSET - LANG_OFFSET) // available language space
+#define DUMP_SIZE (XFLASH_SIZE - DUMP_OFFSET) // effective dump size area