diff --git a/lib/libc/gen/sched_getaffinity.c b/lib/libc/gen/sched_getaffinity.c
--- a/lib/libc/gen/sched_getaffinity.c
+++ b/lib/libc/gen/sched_getaffinity.c
@@ -30,12 +30,26 @@
 #include <sched.h>
 #include <string.h>
 
+#include "libc_private.h"
+
+#define	KERNEL_TIDPID_FIRST	1400079
+#define	KERNEL_TIDPID_PID_MAX	99999
+
 int
 sched_getaffinity(pid_t pid, size_t cpusetsz, cpuset_t *cpuset)
 {
+	cpuwhich_t which;
 	int error;
 
-	error = cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TIDPID,
+	if (__getosreldate() < KERNEL_TIDPID_FIRST) {
+		if (pid == 0 || pid > KERNEL_TIDPID_PID_MAX)
+			which = CPU_WHICH_TID;
+		else
+			which = CPU_WHICH_PID;
+	} else
+		which = CPU_WHICH_TIDPID;
+
+	error = cpuset_getaffinity(CPU_LEVEL_WHICH, which,
 	    pid == 0 ? -1 : pid, cpusetsz, cpuset);
 	if (error == -1 && errno == ERANGE)
 		errno = EINVAL;
diff --git a/lib/libc/gen/sched_setaffinity.c b/lib/libc/gen/sched_setaffinity.c
--- a/lib/libc/gen/sched_setaffinity.c
+++ b/lib/libc/gen/sched_setaffinity.c
@@ -32,14 +32,28 @@
 #include <sched.h>
 #include <string.h>
 
+#include "libc_private.h"
+
+#define	KERNEL_TIDPID_FIRST	1400079
+#define	KERNEL_TIDPID_PID_MAX	99999
+
 int
 sched_setaffinity(pid_t pid, size_t cpusetsz, const cpuset_t *cpuset)
 {
 	static int mp_maxid;
+	cpuwhich_t which;
 	cpuset_t c;
 	int error, lbs, cpu;
 	size_t len, sz;
 
+	if (__getosreldate() < KERNEL_TIDPID_FIRST) {
+		if (pid == 0 || pid > KERNEL_TIDPID_PID_MAX)
+			which = CPU_WHICH_TID;
+		else
+			which = CPU_WHICH_PID;
+	} else
+		which = CPU_WHICH_TIDPID;
+
 	sz = cpusetsz > sizeof(cpuset_t) ? sizeof(cpuset_t) : cpusetsz;
 	memset(&c, 0, sizeof(c));
 	memcpy(&c, cpuset, sz);
@@ -58,7 +72,7 @@
 			if (cpu > mp_maxid)
 				CPU_CLR(cpu, &c);
 	}
-	error = cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TIDPID,
+	error = cpuset_setaffinity(CPU_LEVEL_WHICH, which,
 	    pid == 0 ? -1 : pid, sizeof(cpuset_t), &c);
 	if (error == -1 && errno == EDEADLK)
 		errno = EINVAL;