diff --git a/bdk/memory_map.h b/bdk/memory_map.h
index 467364e..e24d924 100644
--- a/bdk/memory_map.h
+++ b/bdk/memory_map.h
@@ -17,7 +17,6 @@
 #ifndef _MEMORY_MAP_H_
 #define _MEMORY_MAP_H_
 
-//#define IPL_STACK_TOP  0x4003FF00
 /* --- BIT/BCT: 0x40000000 - 0x40003000 --- */
 /* ---     IPL: 0x40008000 - 0x40028000 --- */
 #define LDR_LOAD_ADDR     0x40007000
@@ -25,13 +24,20 @@
 #define IPL_LOAD_ADDR     0x40008000
 #define  IPL_SZ_MAX          SZ_128K
 
-/* --- XUSB EP context and TRB ring buffers --- */
-#define XUSB_RING_ADDR    0x40020000
+#define XUSB_RING_ADDR    0x40020000 // XUSB EP context and TRB ring buffers.
 
-#define SECMON_MIN_START  0x4002B000
+#define SECMON_MIN_START  0x4002B000 // Minimum reserved address for secmon.
 
 #define SDRAM_PARAMS_ADDR 0x40030000 // SDRAM extraction buffer during sdram init.
-#define CBFS_DRAM_EN_ADDR 0x4003e000 // u32.
+
+/* start.S / exception_handlers.S */
+#define SYS_STACK_TOP_INIT 0x4003FF00
+#define FIQ_STACK_TOP      0x40040000
+#define IRQ_STACK_TOP      0x40040000
+#define IPL_RELOC_ADDR     0x4003FF00
+#define  IPL_RELOC_SZ            0x10
+#define EXCP_STORAGE_ADDR  0x4003FFF0
+#define  EXCP_STORAGE_SZ         0x10
 
 /* --- DRAM START --- */
 #define DRAM_START     0x80000000
@@ -95,6 +101,7 @@
 #define NYX_FB2_ADDRESS  0xF6600000
 #define  NYX_FB_SZ         0x384000 // 1280 x 720 x 4.
 
+/* OBSOLETE: Very old hwinit based payloads were setting a carveout here. */
 #define DRAM_MEM_HOLE_ADR 0xF6A00000
 #define DRAM_MEM_HOLE_SZ   0x8140000
 /* ---   Hole: 129MB 0xF6A00000 - 0xFEB3FFFF --- */