commit 3bd3d6b0bf9b8f054a8b31c716f03e2d0dd8751f
Author: Jim Fehlig <jfehlig@novell.com>
Date:   Wed Jan 27 10:56:18 2010 -0700

    Support Xen 4.0 sysctl version 7
    
    xen-unstable c/s 20762 bumped XEN_SYSCTL_INTERFACE_VERSION to 7.  The
    interface change does not affect libvirt, other than xenHypervisorInit()
    failing since version 7 is not tried.
    
    The attached patch accommodates the upcoming Xen 4.0 release by checking
    for XEN_SYSCTL_INTERFACE_VERSION 7.  If found, it sets
    XEN_DOMCTL_INTERFACE_VERSION to 6, which is also new to Xen 4.0.

diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
index 6d8accc..7f39095 100644
--- a/src/xen/xen_hypervisor.c
+++ b/src/xen/xen_hypervisor.c
@@ -2100,12 +2100,14 @@ xenHypervisorInit(void)
             DEBUG0("Using hypervisor call v2, sys ver6 dom ver5\n");
             goto done;
         }
-        /* Xen 4.0 */
+    }
+
+    /* Xen 4.0 */
+    sys_interface_version = 7; /* XEN_SYSCTL_INTERFACE_VERSION */
+    if (virXen_getdomaininfo(fd, 0, &info) == 1) {
         dom_interface_version = 6; /* XEN_DOMCTL_INTERFACE_VERSION */
-        if (virXen_getvcpusinfo(fd, 0, 0, ipt, NULL, 0) == 0){
-            DEBUG0("Using hypervisor call v2, sys ver6 dom ver6\n");
-            goto done;
-        }
+        DEBUG0("Using hypervisor call v2, sys ver7 dom ver6\n");
+        goto done;
     }
 
     hypervisor_version = 1;