Index: src/sys/kern/kern_todr.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_todr.c,v
retrieving revision 1.52
diff -u -r1.52 kern_todr.c
--- src/sys/kern/kern_todr.c	4 Jan 2026 02:09:03 -0000	1.52
+++ src/sys/kern/kern_todr.c	4 Sep 2026 13:52:55 -0000
@@ -78,7 +78,9 @@
 #include <sys/device_calls.h>
 #include <sys/intr.h>
 #include <sys/kernel.h>
+#include <sys/kmem.h>
 #include <sys/mutex.h>
+#include <sys/queue.h>
 #include <sys/rndsource.h>
 #include <sys/sdt.h>
 #include <sys/systm.h>
@@ -89,8 +91,14 @@
 static int todr_gettime(todr_chip_handle_t, struct timeval *);
 static int todr_settime(todr_chip_handle_t, struct timeval *);
 
+struct todr_entry {
+	todr_chip_handle_t todr_handle;
+	SIMPLEQ_ENTRY(todr_entry) todr_entries;
+};
+static SIMPLEQ_HEAD(, todr_entry) todr_head =
+    SIMPLEQ_HEAD_INITIALIZER(todr_head);
+
 static kmutex_t todr_mutex;
-static todr_chip_handle_t todr_handle;
 static bool todr_initialized;
 
 /* The minimum reasonable RTC date before preposterousness */
@@ -179,6 +187,7 @@
 void
 todr_attach(todr_chip_handle_t todr)
 {
+	struct todr_entry *todrp;
 
 	/*
 	 * todr_init() is called very early in main(), but this is
@@ -191,13 +200,15 @@
 		return;
 	}
 
+	todrp = kmem_alloc(sizeof(struct todr_entry), KM_SLEEP);
 	todr_lock();
-	if (todr_handle) {
-		todr_unlock();
-		printf("todr_attach: TOD already configured\n");
-		return;
+	if (SIMPLEQ_EMPTY(&todr_head)) {
+		SIMPLEQ_INSERT_HEAD(&todr_head, todrp, todr_entries);
+	} else {
+		SIMPLEQ_INSERT_TAIL(&todr_head, todrp, todr_entries);
+		printf("%s: secondary clock\n", device_xname(todr->todr_dev));
 	}
-	todr_handle = todr;
+	todrp->todr_handle = todr;
 	todr_unlock();
 }
 
@@ -217,7 +228,10 @@
 	bool goodtime = false;
 	bool badrtc = false;
 	struct timespec ts;
-	struct timeval tv;
+	struct timeval tv, tv2;
+	struct todr_entry *todrp;
+	device_t t_dev;
+	time_t deltat;
 
 	KASSERT(todr_lock_owned());
 
@@ -246,22 +260,28 @@
 	/*
 	 * Some ports need to be supplied base in order to fabricate a time_t.
 	 */
-	if (todr_handle)
-		todr_handle->todr_base_time = base;
+	if (SIMPLEQ_EMPTY(&todr_head)) {
+		todrp = NULL;
+	} else {
+		todrp = SIMPLEQ_FIRST(&todr_head);
+		if (todrp->todr_handle != NULL)
+			todrp->todr_handle->todr_base_time = base;
+	}
 
 	memset(&tv, 0, sizeof(tv));
 
-	if ((todr_handle == NULL) ||
-	    (todr_gettime(todr_handle, &tv) != 0) ||
+	/* Note, that we use the first RTC for system time. */
+	if ((todrp == NULL) || (todrp->todr_handle == NULL) ||
+	    (todr_gettime(todrp->todr_handle, &tv) != 0) ||
 	    (tv.tv_sec < (PREPOSTEROUS_YEARS * SECS_PER_COMMON_YEAR))) {
 
-		if (todr_handle != NULL)
+		if ((todrp != NULL) && (todrp->todr_handle != NULL))
 			printf("WARNING: preposterous TOD clock time\n");
 		else
 			printf("WARNING: no TOD clock present\n");
 		badrtc = true;
 	} else {
-		time_t deltat = tv.tv_sec - base;
+		deltat = tv.tv_sec - base;
 
 		if (deltat < 0)
 			deltat = -deltat;
@@ -301,6 +321,29 @@
 		tv.tv_usec = 0;
 	}
 
+	/* Check other clocks, if any, against our time */
+	todrp = SIMPLEQ_FIRST(&todr_head);
+	while ((todrp = SIMPLEQ_NEXT(todrp, todr_entries)) != NULL) {
+		if ((todrp->todr_handle == NULL) || 
+		    (todr_gettime(todrp->todr_handle, &tv2) != 0))
+			continue;
+		t_dev = todrp->todr_handle->todr_dev;
+		if (tv2.tv_sec < (PREPOSTEROUS_YEARS * SECS_PER_COMMON_YEAR)) {
+			printf("WARNING: preposterous %s clock time\n",
+			    device_xname(t_dev));
+			deltat = 0;
+		} else {
+			deltat = tv.tv_sec - tv2.tv_sec;
+			rnd_add_data(NULL, &tv, sizeof(tv), 0);
+		}
+		if (deltat < -10)
+			printf("WARNING: %s clock lost %" PRId64 " seconds\n",
+			    device_xname(t_dev), deltat);
+		if (deltat > 10)
+			printf("WARNING: %s clock gained %" PRId64 " seconds\n",
+			    device_xname(t_dev), deltat);
+	}
+
 	timeset = true;
 
 	ts.tv_sec = tv.tv_sec;
@@ -315,13 +358,14 @@
 
 /*
  * todr_save_systime:
- *	Save the current system time back to the TOD clock.
+ *	Save the current system time back to the TOD clock(s).
  *	Must be called with the TODR lock held.
  */
 void
 todr_save_systime(void)
 {
 	struct timeval tv;
+	struct todr_entry *todrp;
 
 	KASSERT(todr_lock_owned());
 
@@ -338,9 +382,12 @@
 	if (tv.tv_sec == 0)
 		return;
 
-	if (todr_handle)
-		if (todr_settime(todr_handle, &tv) != 0)
-			printf("Cannot set TOD clock time\n");
+	todrp = SIMPLEQ_FIRST(&todr_head);
+	SIMPLEQ_FOREACH(todrp, &todr_head, todr_entries)
+		if ((todrp->todr_handle != NULL) &&
+		    (todr_settime(todrp->todr_handle, &tv) != 0))
+			printf("Cannot set %s TOD clock time\n",
+			    device_xname(todrp->todr_handle->todr_dev));
 }
 
 /*
Index: src/sys/arch/sparc64/conf/GENERIC
===================================================================
RCS file: /cvsroot/src/sys/arch/sparc64/conf/GENERIC,v
retrieving revision 1.253
diff -u -r1.253 GENERIC
--- src/sys/arch/sparc64/conf/GENERIC	28 Aug 2026 21:16:34 -0000	1.253
+++ src/sys/arch/sparc64/conf/GENERIC	3 Sep 2026 07:34:58 -0000
@@ -847,6 +847,7 @@
 seeprom*	at iic? addr?	# i2c-at24c64 fru's
 pcagpio* 	at iic? addr?	# V210/V240 GPIO's
 pcf8574io* 	at iic? addr?	# E250 GPIO's
+dsrtc* 		at iic? addr?	# RSC clock found on V210/V240
 
 auxfan* 	at iic? addr?	# iic fan sensor found on SB2500