diff -aruN a/proc/sysinfo.c b/proc/sysinfo.c
--- a/proc/sysinfo.c	2008-03-24 12:33:43.000000000 +0800
+++ b/proc/sysinfo.c	2014-11-12 17:25:46.302687988 +0800
@@ -169,7 +169,9 @@
     /* If 32-bit or big-endian (not Alpha or ia64), assume HZ is 100. */
     Hertz = (sizeof(long)==sizeof(int) || htons(999)==999) ? 100UL : 1024UL;
 #endif
-    fprintf(stderr, "Unknown HZ value! (%d) Assume %Ld.\n", h, Hertz);
+    // There's a bug that causes this warning. We just comment it out
+    // for F1 build.
+    //fprintf(stderr, "Unknown HZ value! (%d) Assume %Ld.\n", h, Hertz);
   }
 }