Index: head/lib/libc/sys/kqueue.2
===================================================================
--- head/lib/libc/sys/kqueue.2
+++ head/lib/libc/sys/kqueue.2
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 29, 2015
+.Dd August 4, 2015
 .Dt KQUEUE 2
 .Os
 .Sh NAME
@@ -288,6 +288,14 @@
 .Va data
 contains the offset from current position to end of file,
 and may be negative.
+.Pp
+This behavior is different from
+.Xr poll 2 ,
+where read events are triggered for regular files unconditionally.
+This event can be triggered unconditionally by setting the
+.Dv NOTE_FILE_POLL
+flag in
+.Va fflags .
 .It "Fifos, Pipes"
 Returns when the there is data to read;
 .Va data
Index: head/sys/kern/vfs_subr.c
===================================================================
--- head/sys/kern/vfs_subr.c
+++ head/sys/kern/vfs_subr.c
@@ -4622,7 +4622,7 @@
 
 	VI_LOCK(vp);
 	kn->kn_data = va.va_size - kn->kn_fp->f_offset;
-	res = (kn->kn_data != 0);
+	res = (kn->kn_sfflags & NOTE_FILE_POLL) != 0 || kn->kn_data != 0;
 	VI_UNLOCK(vp);
 	return (res);
 }
Index: head/sys/sys/event.h
===================================================================
--- head/sys/sys/event.h
+++ head/sys/sys/event.h
@@ -108,6 +108,7 @@
  * data/hint flags for EVFILT_{READ|WRITE}, shared with userspace
  */
 #define NOTE_LOWAT	0x0001			/* low water mark */
+#define NOTE_FILE_POLL	0x0002			/* behave like poll() */
 
 /*
  * data/hint flags for EVFILT_VNODE, shared with userspace