[Xen-devel] [PATCH 7/24] [xen-unstable.hg] don't hard code xenstore/console domid when creating evtchns for new domU

[Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>]

This patch implements a way to determine in which domains the console
and xenstore daemons reside. If each of the files
/var/run/{console,xenstore}.did contains an integer, this integer is
interpreted as the domain id for that daemon. The default or fallback is
domid=0, of course. Here, xend is modified to use this mechanism for the
allocated unbound ports.

This patch also make XenDomainInfo use the resulting domids when creating
the xenstore and console channels for a new or resumed domain.

TODO: The patch xend_rename_xenstore_domain moves read_domid to a more
global location. If that patch is kept, this should just create a global
function directly.

A previous version of this patch was sent to xen-devel. See
http://lists.xensource.com/archives/html/xen-devel/2008-07/msg00610.html

Signed-off-by: Diego Ongaro <diego.ongaro@xxxxxxxxxx>
Signed-off-by: Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>
---

diff -r 277248efe8ae tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py   Fri Aug 01 16:50:31 2008 +0100
+++ b/tools/python/xen/xend/XendDomainInfo.py   Fri Aug 01 16:50:33 2008 +0100
@@ -2501,17 +2501,26 @@
     def _createChannels(self):
         """Create the channels to the domain.
         """
-        self.store_port = self._createChannel()
-        self.console_port = self._createChannel()
+        def read_domid(service):
+            try:
+                f = open("/var/run/%s.did" % service)
+                try:
+                    return int(f.read())
+                finally:
+                    f.close()
+            except (IOError, ValueError):
+                return 0 # assume domain 0 is providing service
 
+        self.store_port = self._createChannel(read_domid("xenstore"))
+        self.console_port = self._createChannel(read_domid("console"))
 
-    def _createChannel(self):
+    def _createChannel(self, remote_dom):
         """Create an event channel to the domain.
         """
         try:
             if self.domid != None:
                 return xc.evtchn_alloc_unbound(domid = self.domid,
-                                               remote_dom = 0)
+                                               remote_dom = remote_dom)
         except:
             log.exception("Exception in alloc_unbound(%s)", str(self.domid))
             raise


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