diff -aupr src.orig/lib/libc/amd64/sys/__vdso_gettc.c src/lib/libc/amd64/sys/__vdso_gettc.c
--- src.orig/lib/libc/amd64/sys/__vdso_gettc.c	2017-09-29 02:20:13.000000000 +0200
+++ src/lib/libc/amd64/sys/__vdso_gettc.c	2018-01-04 16:53:31.590961000 +0100
@@ -30,17 +30,22 @@ __FBSDID("$FreeBSD: releng/10.4/lib/libc
 #include <sys/elf.h>
 #include <sys/time.h>
 #include <sys/vdso.h>
+#include <errno.h>
 #include <machine/cpufunc.h>
 #include "libc_private.h"
 
 static u_int
 __vdso_gettc_low(const struct vdso_timehands *th)
 {
+#if 0
 	uint32_t rv;
 
 	__asm __volatile("rdtsc; shrd %%cl, %%edx, %0"
 	    : "=a" (rv) : "c" (th->th_x86_shift) : "edx");
 	return (rv);
+#else
+	return (0);
+#endif
 }
 
 #pragma weak __vdso_gettc
@@ -48,7 +53,11 @@ u_int
 __vdso_gettc(const struct vdso_timehands *th)
 {
 
+#if 0
 	return (th->th_x86_shift > 0 ? __vdso_gettc_low(th) : rdtsc32());
+#else
+	return (0);
+#endif
 }
 
 #pragma weak __vdso_gettimekeep
@@ -56,5 +65,9 @@ int
 __vdso_gettimekeep(struct vdso_timekeep **tk)
 {
 
+#if 0
 	return (_elf_aux_info(AT_TIMEKEEP, tk, sizeof(*tk)));
+#else
+	return (ENOSYS);
+#endif
 }
diff -aupr src.orig/lib/libc/i386/sys/__vdso_gettc.c src/lib/libc/i386/sys/__vdso_gettc.c
--- src.orig/lib/libc/i386/sys/__vdso_gettc.c	2017-09-29 02:20:14.000000000 +0200
+++ src/lib/libc/i386/sys/__vdso_gettc.c	2018-01-04 17:03:03.096724000 +0100
@@ -30,17 +30,22 @@ __FBSDID("$FreeBSD: releng/10.4/lib/libc
 #include <sys/elf.h>
 #include <sys/time.h>
 #include <sys/vdso.h>
+#include <errno.h>
 #include <machine/cpufunc.h>
 #include "libc_private.h"
 
 static u_int
 __vdso_gettc_low(const struct vdso_timehands *th)
 {
+#if 0
 	uint32_t rv;
 
 	__asm __volatile("rdtsc; shrd %%cl, %%edx, %0"
 	    : "=a" (rv) : "c" (th->th_x86_shift) : "edx");
 	return (rv);
+#else
+	return (0);
+#endif
 }
 
 #pragma weak __vdso_gettc
@@ -48,7 +53,11 @@ u_int
 __vdso_gettc(const struct vdso_timehands *th)
 {
 
+#if 0
 	return (th->th_x86_shift > 0 ? __vdso_gettc_low(th) : rdtsc32());
+#else
+	return (0);
+#endif
 }
 
 #pragma weak __vdso_gettimekeep
@@ -56,5 +65,9 @@ int
 __vdso_gettimekeep(struct vdso_timekeep **tk)
 {
 
+#if 0
 	return (_elf_aux_info(AT_TIMEKEEP, tk, sizeof(*tk)));
+#else
+	return (ENOSYS);
+#endif
 }