Index: sys/sparc64/include/ktr.h
===================================================================
--- sys/sparc64/include/ktr.h	(revision 222201)
+++ sys/sparc64/include/ktr.h	(working copy)
@@ -85,7 +85,9 @@
 	lduw	[PCPU(MID)], r1 ; \
 	mov	1, r2 ; \
 	sllx	r2, r1, r1 ; \
+#if 0
 	TEST(ktr_cpumask, r1, r2, r3, l3) ; \
+#endif
 	ATR(desc, r1, r2, r3, l1, l2)
 
 #endif /* LOCORE */
Index: sys/conf/NOTES
===================================================================
--- sys/conf/NOTES	(revision 222201)
+++ sys/conf/NOTES	(working copy)
@@ -441,7 +441,7 @@
 options 	KTR_ENTRIES=1024
 options 	KTR_COMPILE=(KTR_INTR|KTR_PROC)
 options 	KTR_MASK=KTR_INTR
-options 	KTR_CPUMASK=0x3
+options 	KTR_CPUMASK=("0x3")
 options 	KTR_VERBOSE
 
 #
Index: sys/kern/kern_ktr.c
===================================================================
--- sys/kern/kern_ktr.c	(revision 222201)
+++ sys/kern/kern_ktr.c	(working copy)
@@ -40,8 +40,10 @@
 #include "opt_alq.h"
 
 #include <sys/param.h>
+#include <sys/queue.h>
 #include <sys/alq.h>
 #include <sys/cons.h>
+#include <sys/cpuset.h>
 #include <sys/kernel.h>
 #include <sys/ktr.h>
 #include <sys/libkern.h>
@@ -68,10 +70,6 @@
 #define	KTR_MASK	(0)
 #endif
 
-#ifndef KTR_CPUMASK
-#define	KTR_CPUMASK	(~0)
-#endif
-
 #ifndef KTR_TIME
 #define	KTR_TIME	get_cyclecount()
 #endif
@@ -84,10 +82,10 @@
 
 SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
 
-int	ktr_cpumask = KTR_CPUMASK;
-TUNABLE_INT("debug.ktr.cpumask", &ktr_cpumask);
-SYSCTL_INT(_debug_ktr, OID_AUTO, cpumask, CTLFLAG_RW,
-    &ktr_cpumask, 0, "Bitmask of CPUs on which KTR logging is enabled");
+static char ktr_cpumask[CPUSETBUFSIZ];
+TUNABLE_STR("debug.ktr.cpumask", ktr_cpumask, sizeof(ktr_cpumask));
+SYSCTL_STRING(_debug_ktr, OID_AUTO, cpumask, CTLFLAG_RW, ktr_cpumask,
+    sizeof(ktr_cpumask), "Bitmask of CPUs on which KTR logging is enabled");
 
 int	ktr_mask = KTR_MASK;
 TUNABLE_INT("debug.ktr.mask", &ktr_mask);
@@ -198,6 +196,7 @@
     u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
     u_long arg6)
 {
+	cpuset_t intern_cpumask;
 	struct ktr_entry *entry;
 #ifdef KTR_ALQ
 	struct ale *ale = NULL;
@@ -212,8 +211,16 @@
 		return;
 	if ((ktr_mask & mask) == 0)
 		return;
+#ifndef KTR_CPUMASK
+	CPU_FILL(&intern_cpumask);
+#else
+	if (ktr_cpumask[0] == '\0')
+		strncpy(ktr_cpumask, KTR_CPUMASK, sizeof(ktr_cpumask));
+	if (cpusetobj_strscan(&intern_cpumask, ktr_cpumask) == -1)
+		return;
+#endif
 	cpu = KTR_CPU;
-	if (((1 << cpu) & ktr_cpumask) == 0)
+	if (!CPU_ISSET(cpu, &intern_cpumask))
 		return;
 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
 	td = curthread;
Index: sys/kern/kern_cpuset.c
===================================================================
--- sys/kern/kern_cpuset.c	(revision 222201)
+++ sys/kern/kern_cpuset.c	(working copy)
@@ -50,6 +50,7 @@
 #include <sys/cpuset.h>
 #include <sys/sx.h>
 #include <sys/queue.h>
+#include <sys/libkern.h>
 #include <sys/limits.h>
 #include <sys/bus.h>
 #include <sys/interrupt.h>
@@ -660,6 +661,41 @@
 }
 
 /*
+ * Build a valid cpuset_t object from a string representation.
+ * It expects an incoming buffer at least sized as CPUSETBUFSIZ.
+ */
+int
+cpusetobj_strscan(cpuset_t *set, const char *buf)
+{
+	u_int nwords;
+	int i;
+
+	if (strlen(buf) > CPUSETBUFSIZ - 1)
+		return (-1);
+
+	/* Allow to pass a shorter version of the mask when necessary. */
+	nwords = 1;
+	for (i = 0; buf[i] != '\0'; i++)
+		if (buf[i] == ',')
+			nwords++;
+	if (nwords > _NCPUWORDS)
+		return (-1);
+
+	CPU_ZERO(set);
+	for (i = nwords - 1; i > 0; i--) {
+		if (!sscanf(buf, "%lx, ", &set->__bits[i]))
+			return (-1);
+		buf = strstr(buf, " ");
+		if (buf == NULL)
+			return (-1);
+		buf++;
+	}
+	if (!sscanf(buf, "%lx", &set->__bits[0]))
+		return (-1);
+	return (0);
+}
+
+/*
  * Apply an anonymous mask to a single thread.
  */
 int
Index: sys/sys/cpuset.h
===================================================================
--- sys/sys/cpuset.h	(revision 222201)
+++ sys/sys/cpuset.h	(working copy)
@@ -216,6 +216,7 @@
 int	cpuset_setproc_update_set(struct proc *, struct cpuset *);
 int	cpusetobj_ffs(const cpuset_t *);
 char	*cpusetobj_strprint(char *, const cpuset_t *);
+int	cpusetobj_strscan(cpuset_t *, const char *);
 
 #else
 __BEGIN_DECLS
Index: sys/sys/ktr.h
===================================================================
--- sys/sys/ktr.h	(revision 222201)
+++ sys/sys/ktr.h	(working copy)
@@ -107,7 +107,6 @@
 	u_long	ktr_parms[KTR_PARMS];
 };
 
-extern int ktr_cpumask;
 extern int ktr_mask;
 extern int ktr_entries;
 extern int ktr_verbose;