diff --git a/libc/kernel/arch-arm/asm/pgtable-hwdef.h b/libc/kernel/arch-arm/asm/pgtable-hwdef.h
index 47e8675..7678ba3 100644
--- a/libc/kernel/arch-arm/asm/pgtable-hwdef.h
+++ b/libc/kernel/arch-arm/asm/pgtable-hwdef.h
@@ -7,64 +7,77 @@
  ***   structures, and macros generated from the original header, and thus,
  ***   contains no copyrightable information.
  ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
  ****************************************************************************
  ****************************************************************************/
 #ifndef _ASMARM_PGTABLE_HWDEF_H
 #define _ASMARM_PGTABLE_HWDEF_H
-
 #define PMD_TYPE_MASK (3 << 0)
 #define PMD_TYPE_FAULT (0 << 0)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_TYPE_TABLE (1 << 0)
 #define PMD_TYPE_SECT (2 << 0)
 #define PMD_BIT4 (1 << 4)
 #define PMD_DOMAIN(x) ((x) << 5)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_PROTECTION (1 << 9)  
-
 #define PMD_SECT_BUFFERABLE (1 << 2)
 #define PMD_SECT_CACHEABLE (1 << 3)
 #define PMD_SECT_XN (1 << 4)  
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_SECT_AP_WRITE (1 << 10)
 #define PMD_SECT_AP_READ (1 << 11)
 #define PMD_SECT_TEX(x) ((x) << 12)  
 #define PMD_SECT_APX (1 << 15)  
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_SECT_S (1 << 16)  
 #define PMD_SECT_nG (1 << 17)  
 #define PMD_SECT_SUPER (1 << 18)  
-
 #define PMD_SECT_UNCACHED (0)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_SECT_BUFFERED (PMD_SECT_BUFFERABLE)
 #define PMD_SECT_WT (PMD_SECT_CACHEABLE)
 #define PMD_SECT_WB (PMD_SECT_CACHEABLE | PMD_SECT_BUFFERABLE)
 #define PMD_SECT_MINICACHE (PMD_SECT_TEX(1) | PMD_SECT_CACHEABLE)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PMD_SECT_WBWA (PMD_SECT_TEX(1) | PMD_SECT_CACHEABLE | PMD_SECT_BUFFERABLE)
 #define PMD_SECT_NONSHARED_DEV (PMD_SECT_TEX(2))
-
 #define PTE_TYPE_MASK (3 << 0)
 #define PTE_TYPE_FAULT (0 << 0)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_TYPE_LARGE (1 << 0)
 #define PTE_TYPE_SMALL (2 << 0)
 #define PTE_TYPE_EXT (3 << 0)  
 #define PTE_BUFFERABLE (1 << 2)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_CACHEABLE (1 << 3)
-
 #define PTE_EXT_XN (1 << 0)  
 #define PTE_EXT_AP_MASK (3 << 4)
 #define PTE_EXT_AP0 (1 << 4)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_EXT_AP1 (2 << 4)
 #define PTE_EXT_AP_UNO_SRO (0 << 4)
 #define PTE_EXT_AP_UNO_SRW (PTE_EXT_AP0)
 #define PTE_EXT_AP_URO_SRW (PTE_EXT_AP1)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_EXT_AP_URW_SRW (PTE_EXT_AP1|PTE_EXT_AP0)
 #define PTE_EXT_TEX(x) ((x) << 6)  
 #define PTE_EXT_APX (1 << 9)  
 #define PTE_EXT_COHERENT (1 << 9)  
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_EXT_SHARED (1 << 10)  
 #define PTE_EXT_NG (1 << 11)  
-
 #define PTE_SMALL_AP_MASK (0xff << 4)
 #define PTE_SMALL_AP_UNO_SRO (0x00 << 4)
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define PTE_SMALL_AP_UNO_SRW (0x55 << 4)
 #define PTE_SMALL_AP_URO_SRW (0xaa << 4)
 #define PTE_SMALL_AP_URW_SRW (0xff << 4)
-
 #endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */