Convert libxl driver to Xen 4.2

Based on a patch originally authored by Daniel De Graaf

  http://lists.xen.org/archives/html/xen-devel/2012-05/msg00565.html

This patch converts the Xen libxl driver to support only Xen >= 4.2.
Support for Xen 4.1 libxl is dropped since that version of libxl is
designated 'technology preview' only and is incompatible with Xen 4.2
libxl.  Additionally, the default toolstack in Xen 4.1 is still xend,
for which libvirt has a stable, functional driver.
(cherry picked from commit dfa1e1dd)

Conflicts:
	src/libxl/libxl_conf.c - commit e5e8d5 not backported
	src/libxl/libxl_driver.c - commit 1c04f999 not backported

configure.ac

@@ -715,16 +715,14 @@ if test "$with_libxl" != "no" ; then
     fi
     CFLAGS="$CFLAGS $LIBXL_CFLAGS"
     LIBS="$LIBS $LIBXL_LIBS"
-    AC_CHECK_LIB([xenlight], [libxl_domain_create_new], [
+    AC_CHECK_LIB([xenlight], [libxl_ctx_alloc], [
         with_libxl=yes
-        LIBXL_LIBS="$LIBXL_LIBS -lxenlight -lxenstore -lxenctrl -lxenguest -luuid -lutil -lblktapctl"
+        LIBXL_LIBS="$LIBXL_LIBS -lxenlight"
     ],[
         if test "$with_libxl" = "yes"; then
             fail=1
         fi
         with_libxl=no
-    ],[
-        -lxenstore -lxenctrl -lxenguest -luuid -lutil -lblktapctl
     ])
 fi
 
@@ -732,7 +730,7 @@ LIBS="$old_LIBS"
 CFLAGS="$old_CFLAGS"
 
 if test $fail = 1; then
-    AC_MSG_ERROR([You must install the libxl Library to compile libxenlight driver with -lxl])
+    AC_MSG_ERROR([You must install the libxl Library from Xen >= 4.2 to compile libxenlight driver with -lxl])
 fi
 
 if test "$with_libxl" = "yes"; then

docs/drvxen.html.in

@@ -53,6 +53,14 @@
         the <code>/etc/xen</code> directory. It is important not to place
         any other non-config files in this directory.
       </li>
+      <li>
+        <strong>libxl</strong>: Starting with Xen 4.2, the legacy XenD/xm
+        toolstack is deprecated in favor of libxl, also commonly called
+        libxenlight.  libvirt supports this new Xen toolstack via the
+        libxl driver.  If XenD is enabled, the legacy xen driver consisting
+        of the above mentioned channels will be used.  If XenD is disabled,
+        the libxl driver will be used.
+      </li>
     </ul>
 
     <h2><a name="uri">Connections to Xen driver</a></h2>

libvirt.spec.in

@@ -188,8 +188,8 @@
 %endif
 %endif
 
-# Fedora doesn't have new enough Xen for libxl until F16
-%if 0%{?fedora} && 0%{?fedora} < 16
+# Fedora doesn't have new enough Xen for libxl until F18
+%if 0%{?fedora} && 0%{?fedora} < 18
 %define with_libxl 0
 %endif
 

src/libxl/libxl_conf.h

@@ -58,7 +58,7 @@ struct _libxlDriverPrivate {
     FILE *logger_file;
     xentoollog_logger *logger;
     /* libxl ctx for driver wide ops; getVersion, getNodeInfo, ... */
-    libxl_ctx ctx;
+    libxl_ctx *ctx;
 
     virBitmapPtr reservedVNCPorts;
     virDomainObjList domains;
@@ -77,10 +77,8 @@ typedef struct _libxlDomainObjPrivate libxlDomainObjPrivate;
 typedef libxlDomainObjPrivate *libxlDomainObjPrivatePtr;
 struct _libxlDomainObjPrivate {
     /* per domain libxl ctx */
-    libxl_ctx ctx;
-    libxl_waiter *dWaiter;
-    int waiterFD;
-    int eventHdl;
+    libxl_ctx *ctx;
+    libxl_evgen_domain_death *deathW;
 };
 
 # define LIBXL_SAVE_MAGIC "libvirt-xml\n \0 \r"
@@ -100,13 +98,11 @@ virCapsPtr
 libxlMakeCapabilities(libxl_ctx *ctx);
 
 int
-libxlMakeDisk(virDomainDefPtr def, virDomainDiskDefPtr l_dev,
-              libxl_device_disk *x_dev);
+libxlMakeDisk(virDomainDiskDefPtr l_dev, libxl_device_disk *x_dev);
 int
-libxlMakeNic(virDomainDefPtr def, virDomainNetDefPtr l_nic,
-             libxl_device_nic *x_nic);
+libxlMakeNic(virDomainNetDefPtr l_nic, libxl_device_nic *x_nic);
 int
-libxlMakeVfb(libxlDriverPrivatePtr driver, virDomainDefPtr def,
+libxlMakeVfb(libxlDriverPrivatePtr driver,
              virDomainGraphicsDefPtr l_vfb, libxl_device_vfb *x_vfb);
 
 int