diff --git a/usr.sbin/bhyve/gdb.c b/usr.sbin/bhyve/gdb.c
--- a/usr.sbin/bhyve/gdb.c
+++ b/usr.sbin/bhyve/gdb.c
@@ -1485,14 +1485,8 @@
 write_instr(uint8_t *dest, uint8_t *instr, size_t len)
 {
 	memcpy(dest, instr, len);
-#ifdef __arm64__
-	__asm __volatile(
-	    "dc cvau, %0\n"
-	    "dsb ish\n"
-	    "ic ialluis\n"
-	    "dsb ish\n"
-	    : : "r" (dest) : "memory");
-#endif
+	__compiler_membar();
+	__builtin___clear_cache(dest, dest + len);
 }
 
 static void