bhyve(8): Add the netgraph network backend decription to the manpage.

Reviewed by:	vmaffione, bcr
Approved by:	vmaffione (mentor)
Sponsored by:	vstack.com
Differential Revision:	https://reviews.freebsd.org/D24846

usr.sbin/bhyve/bhyve.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 5, 2020
+.Dd May 18, 2020
 .Dt BHYVE 8
 .Os
 .Sh NAME
@@ -291,10 +291,11 @@ If
 is not specified, the device emulation has no backend and can be
 considered unconnected.
 .Pp
-Network devices:
+Network backends:
 .Bl -tag -width 10n
 .It Ar tapN Ns Oo , Ns Ar mac=xx:xx:xx:xx:xx:xx Oc Ns Oo , Ns Ar mtu=N Oc
 .It Ar vmnetN Ns Oo , Ns Ar mac=xx:xx:xx:xx:xx:xx Oc Ns Oo , Ns Ar mtu=N Oc
+.It Ar netgraph,path=ADDRESS,peerhook=HOOK Ns Oo , Ns Ar socket=NAME Oc Ns Oo , Ns Ar hook=HOOK Oc Ns Oo , Ns Ar mac=xx:xx:xx:xx:xx:xx Oc Ns Oo , Ns Ar mtu=N Oc
 .Pp
 If
 .Ar mac
@@ -310,6 +311,27 @@ With virtio-net devices, the
 .Ar mtu
 parameter can be specified to inform the guest about the largest MTU
 that should be allowed, expressed in bytes.
+.Pp
+With netgraph backend, the
+.Ar path
+and
+.Ar peerhook
+parameters must be specified to set the destination node and corresponding hook.
+The optional parameters
+.Ar socket
+and
+.Ar hook
+may be used to set the
+.Xr ng_socket 4
+node name and source hook.
+The
+.Ar ADDRESS ,
+.Ar HOOK
+and
+.Ar NAME
+must comply with
+.Xr netgraph 4
+addressing rules.
 .El
 .Pp
 Block storage devices:
@@ -670,6 +692,8 @@ bhyve -c 2 -m 4G -w -H \\
 .Ed
 .Sh SEE ALSO
 .Xr bhyve 4 ,
+.Xr netgraph 4 ,
+.Xr ng_socket 4 ,
 .Xr nmdm 4 ,
 .Xr vmm 4 ,
 .Xr ethers 5 ,