oeqa: allow persistent image writes in runqemu()

By default, QemuRunner avoids modifying the image files that it boots
into by enabling the qemu snapshot mode. However, some tests may want
to test changes that must persists across reboots, so this mode
should be optional.

This can be combined by copying the image file to a temporary location
first and then booting with that copy. It's also useful when testing
with additional drives attached to a virtual machine.

QemuTinyRunner doesn't use the snapshot parameter and therefore ignores
the new parameter.

Long term, a better way of passing these various configuration
parameters should be used, and perhaps QemuRunner and QemuTinyRunner
can be merged into one again to avoid code duplication. But for now
the patch follows the exiting style.

Also beware that QemuTarget.start() now acts in two different modes
(with or without explicit launch command), and depending on that mode
parameters like discard_writes must be ignored, i.e. not get passed to
launch().

(From OE-Core rev: 969d079a33a57f5a8f7af86d7bab04d35ab07584)

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/targetcontrol.py

@@ -183,11 +183,11 @@ class QemuTarget(BaseTarget):
         logger.info("Qemu log file: %s" % self.qemulog)
         super(QemuTarget, self).deploy()
 
-    def start(self, params=None, ssh=True, extra_bootparams='', runqemuparams='', launch_cmd=''):
+    def start(self, params=None, ssh=True, extra_bootparams='', runqemuparams='', launch_cmd='', discard_writes=True):
         if launch_cmd:
             start = self.runner.launch(get_ip=ssh, launch_cmd=launch_cmd)
         else:
-            start = self.runner.start(params, get_ip=ssh, extra_bootparams=extra_bootparams, runqemuparams=runqemuparams)
+            start = self.runner.start(params, get_ip=ssh, extra_bootparams=extra_bootparams, runqemuparams=runqemuparams, discard_writes=discard_writes)
 
         if start:
             if ssh:

meta/lib/oeqa/utils/commands.py

@@ -225,7 +225,7 @@ def create_temp_layer(templayerdir, templayername, priority=999, recipepathspec=
 
 
 @contextlib.contextmanager
-def runqemu(pn, ssh=True, runqemuparams='', image_fstype=None, launch_cmd=None, qemuparams=None, overrides={}):
+def runqemu(pn, ssh=True, runqemuparams='', image_fstype=None, launch_cmd=None, qemuparams=None, overrides={}, discard_writes=True):
     """
     launch_cmd means directly run the command, don't need set rootfs or env vars.
     """
@@ -278,7 +278,7 @@ def runqemu(pn, ssh=True, runqemuparams='', image_fstype=None, launch_cmd=None,
     try:
         qemu.deploy()
         try:
-            qemu.start(params=qemuparams, ssh=ssh, runqemuparams=runqemuparams, launch_cmd=launch_cmd)
+            qemu.start(params=qemuparams, ssh=ssh, runqemuparams=runqemuparams, launch_cmd=launch_cmd, discard_writes=discard_writes)
         except bb.build.FuncFailed:
             raise Exception('Failed to start QEMU - see the logs in %s' % logdir)
 

meta/lib/oeqa/utils/qemurunner.py

@@ -97,7 +97,7 @@ class QemuRunner:
                 self._dump_host()
                 raise SystemExit
 
-    def start(self, qemuparams = None, get_ip = True, extra_bootparams = None, runqemuparams='', launch_cmd=None):
+    def start(self, qemuparams = None, get_ip = True, extra_bootparams = None, runqemuparams='', launch_cmd=None, discard_writes=True):
         if self.display:
             os.environ["DISPLAY"] = self.display
             # Set this flag so that Qemu doesn't do any grabs as SDL grabs
@@ -118,7 +118,7 @@ class QemuRunner:
             os.environ["DEPLOY_DIR_IMAGE"] = self.deploy_dir_image
 
         if not launch_cmd:
-            launch_cmd = 'runqemu snapshot %s' % runqemuparams
+            launch_cmd = 'runqemu %s %s ' % ('snapshot' if discard_writes else '', runqemuparams)
             if self.use_kvm:
                 logger.info('Using kvm for runqemu')
                 launch_cmd += ' kvm'

meta/lib/oeqa/utils/qemutinyrunner.py

@@ -60,7 +60,7 @@ class QemuTinyRunner(QemuRunner):
             with open(self.logfile, "a") as f:
                 f.write("%s" % msg)
 
-    def start(self, qemuparams = None, ssh=True, extra_bootparams=None, runqemuparams=''):
+    def start(self, qemuparams = None, ssh=True, extra_bootparams=None, runqemuparams='', discard_writes=True):
 
         if self.display:
             os.environ["DISPLAY"] = self.display