1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 83e2efd181e..9db5583b6d3 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -51,6 +51,10 @@ extern int unsynchronized_tsc(void);
 extern int check_tsc_unstable(void);
 extern unsigned long native_calibrate_tsc(void);
 
+#ifdef CONFIG_X86_64
+extern cycles_t vread_tsc(void);
+#endif
+
 /*
  * Boot-time check whether the TSCs are synchronized across
  * all CPUs/cores: