Xen devel - Apr 2008 - Problem in adding a function to tools/python/xen/lowlevel/xc/xc.c

Hi Folks,
I am trying to add a function to tools/python/xen/lowlevel/xc/xc.c and call
that function from XendDomainInfo.py.
The diffs are shown below. the function in question is *xc.register_domm_xen
*as shown below.

The diffs inside XendDomainInfo.py

@@ -2164,6 +2167,14 @@ class XendDomainInfo:

             self.info[''start_time''] = time.time()

+            if self.info.has_key(''backend''):
+                for c in self.info[''backend'']:
+                    if c == "mgmtif":
+                        # Its a Dom-M. handle it accordingly
+                        log.debug("This is a Dom-M")
+                        *xc.register_domm_xen(self.domid)*
+
             self._stateSet(DOM_STATE_RUNNING)
         except VmError, exn:
             log.exception("XendDomainInfo.initDomain: exception
occurred")


The diffs inside xc.c

[root@node4 xc]# hg diff xc.c
diff -r 483d006cc607 tools/python/xen/lowlevel/xc/xc.c
--- a/tools/python/xen/lowlevel/xc/xc.c Fri Apr 25 13:46:27 2008 +0100
+++ b/tools/python/xen/lowlevel/xc/xc.c Sun Apr 27 23:45:48 2008 -0400
@@ -1262,6 +1262,20 @@ static PyObject *pyxc_domain_iomem_permi
     return zero;
 }

+static PyObject *pyxc_register_domm_xen(XcObject *self, PyObject *args)
+{
+    uint32_t dom;
+
+    if (!PyArg_ParseTuple(args, "i", &dom))
+        return NULL;
+
+    if (xc_register_domm_xen(self->xc_handle, dom) != 0)
+        return NULL;
+
+    Py_INCREF(zero);
+    return zero;
+}
+
 static PyObject *pyxc_domain_set_time_offset(XcObject *self, PyObject
*args)
 {
     uint32_t dom;
@@ -1740,6 +1754,13 @@ static PyMethodDef pyxc_methods[] = {
       "Returns: [int] 0 on success; -1 on error.\n" },
 #endif /* __powerpc */

+    { "register_domm_xen",
+      (PyCFunction)pyxc_register_domm_xen,
+      METH_VARARGS, "\n"
+      "Register a Domain as Dom-M \n"
+      " dom        [int]: Domain which is to be treated as Dom-M.\n"
+      "Returns: [int] 0 on success; -1 on error.\n" },
+
 #if defined(__i386__) || defined(__x86_64__)
     { "domain_check_cpuid",
       (PyCFunction)pyxc_dom_check_cpuid,


the code compiles fine and gets executed during "xm create" command.
but
when I try to run the command I get the following error

[root@node4 vm_config_files]# xm create -c pc1_domm
Using config file "./pc1_domm".
Error: error return without exception set
[root@node4 vm_config_files]#

The /var/log/xen/xend.log shows the following error

[2008-04-28 11:27:17 4132] ERROR (XendDomainInfo:443) VM start failed
Traceback (most recent call last):
  File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/XendDomainInfo.py",
line 423, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/XendTask.py",
line 209, in log_progress
    retval = func(*args, **kwds)
  File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/XendDomainInfo.py",
line 2175, in _initDomain
    *xc.register_domm_xen(self.domid)*
SystemError: error return without exception set

So the error happens in the function that I added. I don''t know how to
fix
this problem. interestingly this problem doesn''t happen on a 64 bit OS
running python2.4. I am experiencing this problem on a 32 bit OS running on
a 32 bit machine with python2.4. I tried other python versions 2.4.1 and
2.5.2 but same problem happens.


Could someone please tell me if I am doing anything wrong in the way I am
defining the function? Has someone experienced the same problem?

Thanks for your help.

Sanjay

-- 
----------------------
PhD Candidate, Georgia Tech
http://www.cc.gatech.edu/~ksanjay/


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On Monday, 28 April 2008 at 11:33, sanjay kushwaha wrote:
...
> +static PyObject *pyxc_register_domm_xen(XcObject *self, PyObject *args)
> +{
> +    uint32_t dom;
> +
> +    if (!PyArg_ParseTuple(args, "i", &dom))
> +        return NULL;
> +
> +    if (xc_register_domm_xen(self->xc_handle, dom) != 0)
> +        return NULL;
> +
> +    Py_INCREF(zero);
> +    return zero;
> +}
> +
...
> The /var/log/xen/xend.log shows the following error
> 
> [2008-04-28 11:27:17 4132] ERROR (XendDomainInfo:443) VM start failed
> Traceback (most recent call last):
>   File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/
> XendDomainInfo.py", line 423, in start
>     XendTask.log_progress(31, 60, self._initDomain)
>   File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/
> XendTask.py", line 209, in log_progress
>     retval = func(*args, **kwds)
>   File
"/root/ksanjay/hp/xen-unstable.hg/dist/install/usr/lib/python/xen/xend/
> XendDomainInfo.py", line 2175, in _initDomain
>     xc.register_domm_xen(self.domid)
> SystemError: error return without exception set
I believe this exception means you''re returning NULL. When you do this,
you need
to set an exception message (e.g. using PyErr_Set*) first. Looking at your
code, the culprit is probably the ''return NULL'' after your
call to
xc_register_domm_xen.

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