[tools] testbot/LibvirtTool: Add a proper usage message.

[Francois Gouget]

Signed-off-by: Francois Gouget <fgouget at codeweavers.com>
---
 testbot/bin/LibvirtTool.pl | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/testbot/bin/LibvirtTool.pl b/testbot/bin/LibvirtTool.pl
index 33760d365..df7859dea 100755
--- a/testbot/bin/LibvirtTool.pl
+++ b/testbot/bin/LibvirtTool.pl
@@ -141,6 +141,31 @@ if (!defined $Usage)
 if (defined $Usage)
 {
   print "Usage: $Name0 [--debug] [--log-only] [--help] (checkidle|checkoff|monitor|poweroff|revert) VMName\n";
+  print "\n";
+  print "Prepare the VM for use by the TestBot.\n";
+  print "\n";
+  print "Where:\n";
+  print "  VMName     Is the name of the TestBot VM to work on.\n";
+  print "  checkidle  Checks that the virtual machine is running the appropriate\n";
+  print "             snapshot for the VM and sets the VM status to either idle (if it\n";
+  print "             does), off (if it is powered off) or offline (in case of Libvirt\n";
+  print "             error).\n";
+  print "  checkoff   Checks that the virtual machine is powered off and sets the VM's\n";
+  print "             status to either off (if it is) or offline (in case of Libvirt\n";
+  print "             error).\n";
+  print "  monitor    Tries accessing the virtual machine through Libvirt until success\n";
+  print "             at which time the virtual machine is powered off and the VM\n";
+  print "             status is set to off.\n";
+  print "  poweroff   Powers off the virtual machine and sets the VM status to off.\n";
+  print "  revert     Reverts and powers on the virtual machine to the snapshot\n";
+  print "             specified by the VM. If the snapshot does not exist it may be\n";
+  print "             created from an existing base snapshot by applying configuration\n";
+  print "             options such as powering on the virtual machine, setting the\n";
+  print "             locales, enabling test signing, etc.\n";
+  print "  --debug    More verbose messages for debugging.\n";
+  print "  --log-only Only send error messages to the log instead of also printing them\n";
+  print "             on stderr.\n";
+  print "  --help     Shows this usage message.\n";
   exit $Usage;
 }
 
-- 
2.30.2