mention joy@eap, xref manpage, add warning about use of joy attachment,

from Bjoern Johannesson per PR kern/34054, with minor changes by me

share/man/man4/eap.4

@@ -1,4 +1,4 @@
-.\" $NetBSD: eap.4,v 1.15 2005/06/22 04:19:09 kent Exp $
+.\" $NetBSD: eap.4,v 1.16 2006/08/01 11:25:40 drochner Exp $
 .\"
 .\" Copyright (c) 1999 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -34,7 +34,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd June 22, 2005
+.Dd July 22, 2006
 .Dt EAP 4
 .Os
 .Sh NAME
@@ -43,6 +43,7 @@
 .Sh SYNOPSIS
 .Cd "eap*   at pci? dev ? function ?"
 .Cd "audio* at audiobus?"
+.Cd "joy*   at eap?"
 .Cd "midi*  at eap?"
 .Cd "options EAP_USE_BOTH_DACS"
 .Sh DESCRIPTION
@@ -64,6 +65,7 @@ audio device simultaneously.
 .Sh SEE ALSO
 .Xr ac97 4 ,
 .Xr audio 4 ,
+.Xr joy 4 ,
 .Xr midi 4 ,
 .Xr pci 4
 .Sh HISTORY
@@ -71,3 +73,13 @@ The
 .Nm
 device driver appeared in
 .Nx 1.4 .
+.Sh CAVEATS
+The joystick port hardware works by emulating a legacy
+.Xr isa 4
+joystick port, bypassing the
+.Xr pci 4
+bus method for address allocation.
+This is unlikely to work on PCI busses other than the primary one.
+There is also a possibility for conflicts with real ISA devices
+because the PCI bus is probed before ISA.
+Use with caution.