Add support for saving VM state when a test fails.

lib/cros_vm_lib.sh

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Common vm functions for use in crosutils.
 
 DEFINE_string kvm_pid "" \
   "Use this pid file.  If it exists and is set, use the vm specified by pid."
 DEFINE_boolean no_graphics ${FLAGS_FALSE} "Runs the KVM instance silently."
 DEFINE_boolean persist "${FLAGS_FALSE}" "Persist vm."
 DEFINE_boolean snapshot ${FLAGS_FALSE} "Don't commit changes to image."
 DEFINE_integer ssh_port 9222 "Port to tunnel ssh traffic over."
 DEFINE_string vnc "" "VNC Server to display to instead of SDL."
 
 KVM_PID_FILE=/tmp/kvm.$$.pid
 LIVE_VM_IMAGE=
+KVM_MONITOR_SOCKET=
 
 function get_pid() {
   sudo cat "${KVM_PID_FILE}"
 }
 
 # TODO(rtc): These flags assume that we'll be using KVM on Lucid and won't work
 # on Hardy.
 # $1: Path to the virtual image to start.
 function start_kvm() {
   # Override default pid file.
   [ -n "${FLAGS_kvm_pid}" ] && KVM_PID_FILE=${FLAGS_kvm_pid}
   if [ -e "${KVM_PID_FILE}" ]; then
     local pid=$(get_pid)
     # Check if the process exists.
     if ps -p ${pid} > /dev/null ; then
       echo "Using a pre-created KVM instance specified by ${FLAGS_kvm_pid}." >&2
     else
       # Let's be safe in case they specified a file that isn't a pid file.
       echo "File ${KVM_PID_FILE} exists but specified pid doesn't." >&2
       exit 1
     fi
   else
     # No pid specified by PID file.  Let's create a VM instance in this case.
     echo "Starting a KVM instance" >&2
     local nographics=""
     local usesnapshot=""
+    local save_vm_state=""
     if [ ${FLAGS_no_graphics} -eq ${FLAGS_TRUE} ]; then
       nographics="-nographic -serial none"
     fi
     if [ -n "${FLAGS_vnc}" ]; then
       nographics="-vnc ${FLAGS_vnc}"
     fi
 
     if [ ${FLAGS_snapshot} -eq ${FLAGS_TRUE} ]; then
       snapshot="-snapshot"
     fi
 
+    if [ ${FLAGS_save_vm_state} -eq ${FLAGS_TRUE} ]; then
+      # Redirect the QEMU monitor to the guest usb serial port so tests
+      # can trigger a "savevm" command from inside the guest.
+      KVM_MONITOR_SOCKET=/tmp/kvm.mon.socket.$$
+      save_vm_state="-monitor unix:${KVM_MONITOR_SOCKET},server,nowait
+                     -usbdevice serial::unix:${KVM_MONITOR_SOCKET}"
+    fi
+
     sudo kvm -m 1024 \
       -vga std \
       -pidfile "${KVM_PID_FILE}" \
       -daemonize \
       -net nic,model=e1000 \
       ${nographics} \
       ${snapshot} \
+      ${save_vm_state} \
       -net user,hostfwd=tcp::${FLAGS_ssh_port}-:22 \
       -hda "${1}"
 
     LIVE_VM_IMAGE="${1}"
   fi
 }
 
 # Checks to see if we can access the target virtual machine with ssh.
 function ssh_ping() {
   "$(dirname $0)"/../ssh_test.sh \
@@ skipping 22 matching lines @@
   if [ "${FLAGS_persist}" -eq "${FLAGS_TRUE}" ]; then
     echo "Persist requested.  Use --ssh_port ${FLAGS_ssh_port} " \
       "--kvm_pid ${KVM_PID_FILE} to re-connect to it." >&2
   else
     echo "Stopping the KVM instance" >&2
     local pid=$(get_pid)
     if [ -n "${pid}" ]; then
       echo "Killing ${pid}" >&2
       sudo kill ${pid}
       sudo rm "${KVM_PID_FILE}"
+      if [ -n "${KVM_MONITOR_SOCKET}" ]; then
+        sudo rm "${KVM_MONITOR_SOCKET}"
+      fi
     else
       echo "No kvm pid found to stop." >&2
       return 1
     fi
   fi
 }