+#elif defined(__x86_64__)
+ /*
+ * This is broken because it can generate memory type aliases,
+ * which can cause cache corruptions
+ * But it is only available for root and we have to be bug-to-bug
+ * compatible with i386.
+ */
+ if (file->f_flags & O_SYNC)
+ return 1;
+ /* same behaviour as i386. PAT always set to cached and MTRRs control the
+ caching behaviour.
+ Hopefully a full PAT implementation will fix that soon. */
+ return 0;