fw/target: detect module variations in TargetInfo

- Add modules entry to TargetInfo
- When retrieving TargetInfo from cache, make sure info modules match
  those for the current target, otherwise mark info as stale and
  re-generate.

wa/framework/target/info.py

@@ -221,6 +221,7 @@ class CpuInfo(Podable):
 def get_target_info(target):
     info = TargetInfo()
     info.target = target.__class__.__name__
+    info.modules = target.modules
     info.os = target.os
     info.os_version = target.os_version
     info.system_id = target.system_id
@@ -313,12 +314,13 @@ def cache_target_info(target_info, overwrite=False):
 
 class TargetInfo(Podable):
 
-    _pod_serialization_version = 4
+    _pod_serialization_version = 5
 
     @staticmethod
     def from_pod(pod):
         instance = super(TargetInfo, TargetInfo).from_pod(pod)
         instance.target = pod['target']
+        instance.modules = pod['modules']
         instance.abi = pod['abi']
         instance.cpus = [CpuInfo.from_pod(c) for c in pod['cpus']]
         instance.os = pod['os']
@@ -343,6 +345,7 @@ class TargetInfo(Podable):
     def __init__(self):
         super(TargetInfo, self).__init__()
         self.target = None
+        self.modules = []
         self.cpus = []
         self.os = None
         self.os_version = None
@@ -362,6 +365,7 @@ class TargetInfo(Podable):
     def to_pod(self):
         pod = super(TargetInfo, self).to_pod()
         pod['target'] = self.target
+        pod['modules'] = self.modules
         pod['abi'] = self.abi
         pod['cpus'] = [c.to_pod() for c in self.cpus]
         pod['os'] = self.os
@@ -413,3 +417,7 @@ class TargetInfo(Podable):
     @staticmethod
     def _pod_upgrade_v4(pod):
         return TargetInfo._pod_upgrade_v3(pod)
+
+    @staticmethod
+    def _pod_upgrade_v5(pod):
+        pod['modules'] = pod.get('modules') or []

wa/framework/target/manager.py

@@ -92,9 +92,18 @@ class TargetManager(object):
     @memoized
     def get_target_info(self):
         info = get_target_info_from_cache(self.target.system_id)
+
         if info is None:
             info = get_target_info(self.target)
             cache_target_info(info)
+        else:
+            # If module configuration has changed form when the target info
+            # was previously cached, it is possible additional info will be
+            # available, so should re-generate the cache.
+            if set(info.modules) != set(self.target.modules):
+                info = get_target_info(self.target)
+                cache_target_info(info, overwrite=True)
+
         return info
 
     def reboot(self, context, hard=False):