Index: head/sys/x86/x86/mca.c
===================================================================
--- head/sys/x86/x86/mca.c
+++ head/sys/x86/x86/mca.c
@@ -104,7 +104,8 @@
     "Administrative toggle for logging of spurious corrected errors");
 
 int workaround_erratum383;
-SYSCTL_INT(_hw_mca, OID_AUTO, erratum383, CTLFLAG_RD, &workaround_erratum383, 0,
+SYSCTL_INT(_hw_mca, OID_AUTO, erratum383, CTLFLAG_RD|CTLFLAG_RDTUN,
+    &workaround_erratum383, 0,
     "Is the workaround for Erratum 383 on AMD Family 10h processors enabled?");
 
 static STAILQ_HEAD(, mca_internal) mca_freelist;