diff --git a/libc/kernel/common/linux/dma-mapping.h b/libc/kernel/common/linux/dma-mapping.h
index 6432259..6e78058 100644
--- a/libc/kernel/common/linux/dma-mapping.h
+++ b/libc/kernel/common/linux/dma-mapping.h
@@ -7,42 +7,49 @@
  ***   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 _ASM_LINUX_DMA_MAPPING_H
 #define _ASM_LINUX_DMA_MAPPING_H
-
 #include <linux/device.h>
 #include <linux/err.h>
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 enum dma_data_direction {
  DMA_BIDIRECTIONAL = 0,
  DMA_TO_DEVICE = 1,
  DMA_FROM_DEVICE = 2,
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
  DMA_NONE = 3,
 };
-
 #define DMA_64BIT_MASK 0xffffffffffffffffULL
 #define DMA_48BIT_MASK 0x0000ffffffffffffULL
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define DMA_40BIT_MASK 0x000000ffffffffffULL
 #define DMA_39BIT_MASK 0x0000007fffffffffULL
 #define DMA_32BIT_MASK 0x00000000ffffffffULL
 #define DMA_31BIT_MASK 0x000000007fffffffULL
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define DMA_30BIT_MASK 0x000000003fffffffULL
 #define DMA_29BIT_MASK 0x000000001fffffffULL
 #define DMA_28BIT_MASK 0x000000000fffffffULL
 #define DMA_24BIT_MASK 0x0000000000ffffffULL
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #include <asm/dma-mapping.h>
-
 #define dma_sync_single dma_sync_single_for_cpu
 #define dma_sync_sg dma_sync_sg_for_cpu
-
 #define DMA_MEMORY_MAP 0x01
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define DMA_MEMORY_IO 0x02
 #define DMA_MEMORY_INCLUDES_CHILDREN 0x04
 #define DMA_MEMORY_EXCLUSIVE 0x08
-
 #ifndef ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif
 #endif