Index: sys/dev/cpuctl/cpuctl.c
===================================================================
--- sys/dev/cpuctl/cpuctl.c
+++ sys/dev/cpuctl/cpuctl.c
@@ -362,7 +362,7 @@
 	set_cpu(cpu, td);
 	critical_enter();
 
-	ret = ucode_intel_load(ptr, true);
+	ret = ucode_intel_load(ptr, true, NULL, NULL);
 
 	critical_exit();
 	restore_cpu(oldcpu, is_bound, td);
Index: sys/x86/include/ucode.h
===================================================================
--- sys/x86/include/ucode.h
+++ sys/x86/include/ucode.h
@@ -58,7 +58,8 @@
 	} entries[0];
 };
 
-int	ucode_intel_load(void *data, bool unsafe);
+int	ucode_intel_load(void *data, bool unsafe,
+	    uint64_t *nrevp, uint64_t *orevp);
 size_t	ucode_load_bsp(uintptr_t free);
 void	ucode_load_ap(int cpu);
 void	ucode_reload(void);
Index: sys/x86/x86/ucode.c
===================================================================
--- sys/x86/x86/ucode.c
+++ sys/x86/x86/ucode.c
@@ -59,7 +59,7 @@
 
 static struct ucode_ops {
 	const char *vendor;
-	int (*load)(void *, bool);
+	int (*load)(void *, bool, uint64_t *, uint64_t *);
 	void *(*match)(uint8_t *, size_t *);
 } loaders[] = {
 	{
@@ -72,35 +72,36 @@
 /* Selected microcode update data. */
 static void *early_ucode_data;
 static void *ucode_data;
+static struct ucode_ops *ucode_loader;
 
-static char errbuf[128];
+static char msgbuf[128];
 
 static void __printflike(1, 2)
-log_err(const char *fmt, ...)
+log_msg(const char *fmt, ...)
 {
 	va_list ap;
 
 	va_start(ap, fmt);
-	vsnprintf(errbuf, sizeof(errbuf), fmt, ap);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
 	va_end(ap);
 }
 
 static void
-print_err(void *arg __unused)
+print_msg(void *arg __unused)
 {
 
-	if (errbuf[0] != '\0')
-		printf("microcode load error: %s\n", errbuf);
+	if (msgbuf[0] != '\0')
+		printf("Microcode: %s\n", msgbuf);
 }
-SYSINIT(ucode_print_err, SI_SUB_CPU, SI_ORDER_FIRST, print_err, NULL);
+SYSINIT(ucode_log, SI_SUB_CPU, SI_ORDER_FIRST, print_msg, NULL);
 
 int
-ucode_intel_load(void *data, bool unsafe)
+ucode_intel_load(void *data, bool unsafe, uint64_t *nrevp, uint64_t *orevp)
 {
-	uint64_t rev0, rev1;
+	uint64_t nrev, orev;
 	uint32_t cpuid[4];
 
-	rev0 = rdmsr(MSR_BIOS_SIGN);
+	orev = rdmsr(MSR_BIOS_SIGN) >> 32;
 
 	/*
 	 * Perform update.  Flush caches first to work around seemingly
@@ -118,8 +119,15 @@
 	 */
 	do_cpuid(0, cpuid);
 
-	rev1 = rdmsr(MSR_BIOS_SIGN);
-	if (rev1 <= rev0)
+	/*
+	 * Verify that the microcode revision changed.
+	 */
+	nrev = rdmsr(MSR_BIOS_SIGN) >> 32;
+	if (nrevp != NULL)
+		*nrevp = nrev;
+	if (orevp != NULL)
+		*orevp = orev;
+	if (nrev <= orev)
 		return (EEXIST);
 	return (0);
 }
@@ -131,7 +139,7 @@
 	int i;
 
 	if (resid < sizeof(struct ucode_intel_header)) {
-		log_err("truncated update header");
+		log_msg("truncated update header");
 		return (1);
 	}
 	size = hdr->total_size;
@@ -140,15 +148,15 @@
 		    sizeof(struct ucode_intel_header);
 
 	if (hdr->header_version != 1) {
-		log_err("unexpected header version %u", hdr->header_version);
+		log_msg("unexpected header version %u", hdr->header_version);
 		return (1);
 	}
 	if (size % 16 != 0) {
-		log_err("unexpected update size %u", hdr->total_size);
+		log_msg("unexpected update size %u", hdr->total_size);
 		return (1);
 	}
 	if (resid < size) {
-		log_err("truncated update");
+		log_msg("truncated update");
 		return (1);
 	}
 
@@ -157,7 +165,7 @@
 	for (i = 0; i < size / sizeof(uint32_t); i++)
 		cksum += data[i];
 	if (cksum != 0) {
-		log_err("checksum failed");
+		log_msg("checksum failed");
 		return (1);
 	}
 	return (0);
@@ -264,7 +272,7 @@
 #endif
 
 	if (ucode_data != NULL)
-		(void)ucode_intel_load(ucode_data, false);
+		(void)ucode_loader->load(ucode_data, false, NULL, NULL);
 }
 
 static void *
@@ -308,11 +316,12 @@
 		uint32_t regs[4];
 		char vendor[13];
 	} cpuid;
-	struct ucode_ops *loader;
 	uint8_t *addr, *fileaddr, *match;
 	char *type;
+	uint64_t nrev, orev;
 	caddr_t file;
 	size_t i, len, ucode_len;
+	int error;
 
 	KASSERT(free % PAGE_SIZE == 0, ("unaligned boundary %p", (void *)free));
 
@@ -320,12 +329,12 @@
 	cpuid.regs[0] = cpuid.regs[1];
 	cpuid.regs[1] = cpuid.regs[3];
 	cpuid.vendor[12] = '\0';
-	for (i = 0, loader = NULL; i < nitems(loaders); i++)
+	for (i = 0; i < nitems(loaders); i++)
 		if (strcmp(cpuid.vendor, loaders[i].vendor) == 0) {
-			loader = &loaders[i];
+			ucode_loader = &loaders[i];
 			break;
 		}
-	if (loader == NULL)
+	if (ucode_loader == NULL)
 		return (0);
 
 	file = 0;
@@ -341,7 +350,7 @@
 
 		fileaddr = preload_fetch_addr(file);
 		len = preload_fetch_size(file);
-		match = loader->match(fileaddr, &len);
+		match = ucode_loader->match(fileaddr, &len);
 		if (match != NULL) {
 			addr = map_ucode(free, len);
 			/* We can't use memcpy() before ifunc resolution. */
@@ -349,7 +358,10 @@
 				addr[i] = ((volatile uint8_t *)match)[i];
 			match = addr;
 
-			if (loader->load(match, false) == 0) {
+			error = ucode_loader->load(match, false, &nrev, &orev);
+			if (error == 0) {
+				log_msg("updated from revision %#jx to %#jx",
+				    (uintmax_t)orev, (uintmax_t)nrev);
 				ucode_data = match;
 				ucode_len = len;
 				early_ucode_data = ucode_data;
@@ -359,7 +371,7 @@
 		}
 	}
 	if (fileaddr != NULL && ucode_data == NULL)
-		log_err("no matching update found");
+		log_msg("no matching update found");
 	return (ucode_len);
 }