diff --git a/libc/kernel/common/asm-generic/percpu.h b/libc/kernel/common/asm-generic/percpu.h
index e498300..55b8b6a 100644
--- a/libc/kernel/common/asm-generic/percpu.h
+++ b/libc/kernel/common/asm-generic/percpu.h
@@ -7,23 +7,27 @@
  ***   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_GENERIC_PERCPU_H_
 #define _ASM_GENERIC_PERCPU_H_
 #include <linux/compiler.h>
-
 #define __GENERIC_PER_CPU
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define DEFINE_PER_CPU(type, name)   __typeof__(type) per_cpu__##name
-
 #define per_cpu(var, cpu) (*((void)(cpu), &per_cpu__##var))
 #define __get_cpu_var(var) per_cpu__##var
 #define __raw_get_cpu_var(var) per_cpu__##var
-
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
-
 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
-
 #endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */