8708 Want diskinfo(1m) to list all disk bays, including those don't have disk installed

@@ -9,19 +9,19 @@
 .\" http://www.illumos.org/license/CDDL.
 .\"
 .\" Copyright 2014 Joyent, Inc.
 .\" Copyright 2016 Nexenta Systems, Inc.
 .\"
-.Dd July 20, 2016
+.Dd October 06, 2017
 .Dt DISKINFO 1M
 .Os
 .Sh NAME
 .Nm diskinfo
 .Nd provide disk device inventory and status
 .Sh SYNOPSIS
 .Nm
-.Op Fl Hp
+.Op Fl aHp
 .Op Fl c Ns | Ns Fl P
 .Sh DESCRIPTION
 The diskinfo tool provides information about the disk devices in the system.
 Because it interacts with the kernel's device management subsystem, this tool
 can be used only from the global zone.

@@ -63,10 +63,12 @@
 See
 .Sx OUTPUT FIELDS
 below for a detailed description of each column.
 .Sh OPTIONS
 .Bl -tag -width Ds
+.It Fl a
+Show all disk bays, including those don't have disks installed.
 .It Fl c
 Select compact mode output.
 At most one of
 .Fl c
 and