From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 7 Dec 2021 10:32:54 +0000 (+0100)
Subject: sys_solaris: disable kernel dosynctodr
X-Git-Tag: 4.2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ebc610fcb365dd0f62800ddbb9e1c4c9cc379a66;p=thirdparty%2Fchrony.git

sys_solaris: disable kernel dosynctodr

The dosynctodr kernel variable needs to be set to 0 to block automatic
synchronization of the system clock to the hardware clock. chronyd used
to disable dosynctodr on Solaris versions before 2.6, but it seems it is
now needed even on current versions as the clock driver sets frequency
only without calling adjtime() or setting the ntp_adjtime() PLL offset.

This issue was reproduced and fix tested on current OpenIndiana.

Fixes: 8feb37df2b48 ("sys_solaris: use timex driver")
---

diff --git a/configure b/configure
index fad03fd7..ac6939ce 100755
--- a/configure
+++ b/configure
@@ -467,7 +467,7 @@ case $OPERATINGSYSTEM in
     ;;
     SunOS)
         EXTRA_OBJECTS="sys_generic.o sys_solaris.o sys_timex.o sys_posix.o"
-        LIBS="$LIBS -lsocket -lnsl -lresolv"
+        LIBS="$LIBS -lsocket -lnsl -lkvm -lelf -lresolv"
         try_setsched=1
         try_lockmem=1
         add_def SOLARIS
diff --git a/sys_solaris.c b/sys_solaris.c
index ba86c11a..24949cbb 100644
--- a/sys_solaris.c
+++ b/sys_solaris.c
@@ -28,16 +28,47 @@
 
 #include "sysincl.h"
 
+#include "logging.h"
 #include "privops.h"
 #include "sys_solaris.h"
 #include "sys_timex.h"
 #include "util.h"
 
+#include <kvm.h>
+#include <nlist.h>
+
+/* ================================================== */
+
+static void
+set_dosynctodr(int on_off)
+{
+  struct nlist nl[] = { {"dosynctodr"}, {NULL} };
+  kvm_t *kt;
+
+  kt = kvm_open(NULL, NULL, NULL, O_RDWR, NULL);
+  if (!kt)
+    LOG_FATAL("Could not open kvm");
+
+  if (kvm_nlist(kt, nl) < 0 || !nl[0].n_value)
+    LOG_FATAL("Could not get dosynctodr address");
+
+  if (kvm_kwrite(kt, nl[0].n_value, &on_off, sizeof (on_off)) < 0)
+    LOG_FATAL("Could not write to dosynctodr");
+
+  kvm_close(kt);
+}
+
 /* ================================================== */
 
 void
 SYS_Solaris_Initialise(void)
 {
+  /* The kernel keeps the system clock and hardware clock synchronised to each
+     other.  The dosynctodr variable needs to be set to zero to prevent the
+     the system clock from following the hardware clock when the system clock
+     is not adjusted by adjtime() or ntp_adjtime(modes=MOD_OFFSET). */
+  set_dosynctodr(0);
+
   /* The kernel allows the frequency to be set in the full range off int32_t */
   SYS_Timex_InitialiseWithFunctions(32500, 1.0 / 100, NULL, NULL, NULL,
                                     0.0, 0.0, NULL, NULL);