kqueue1(2): document

Reviewed by:	emaste, jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D39271

lib/libc/sys/Makefile.inc

@@ -430,6 +430,7 @@ MLINKS+=jail.2 jail_attach.2 \
 	jail.2 jail_set.2
 MLINKS+=kldunload.2 kldunloadf.2
 MLINKS+=kqueue.2 kevent.2 \
+	kqueue.2 kqueue1.2 \
 	kqueue.2 EV_SET.3
 MLINKS+=link.2 linkat.2
 MLINKS+=madvise.2 posix_madvise.2

lib/libc/sys/kqueue.2

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 14, 2022
+.Dd March 26, 2023
 .Dt KQUEUE 2
 .Os
 .Sh NAME
@@ -38,6 +38,8 @@
 .Ft int
 .Fn kqueue "void"
 .Ft int
+.Fn kqueue1 "u_int flags"
+.Ft int
 .Fo kevent
 .Fa "int kq"
 .Fa "const struct kevent *changelist"
@@ -90,6 +92,22 @@ flag, then the descriptor table is shared,
 which will allow sharing of the kqueue between two processes.
 .Pp
 The
+.Fn kqueue1
+system call also creates a new kernel event queue, and additionally takes
+the
+.Fa flags
+argument, which is a bitwise-inclusive OR of the following flags:
+.Bl -tag -width "KQUEUE_CLOEXEC"
+.It Fa KQUEUE_CLOEXEC
+The returned file descriptor is automatically closed on
+.Xr execve 2
+.El
+The
+.Ql fd = kqueue()
+call is equivalent to
+.Ql fd = kqueue1(0) .
+.Pp
+The
 .Fn kevent
 system call
 is used to register events with the queue, and return any pending