libxl: Use libxentoollog in preference to libxenctrl if available.

Upstream Xen is in the process of splitting the (stable API) xtl_*
interfaces out from the (unstable API) libxenctrl library and into a
new (stable API) libxentoollog.

In order to be compatible with Xen both before and after this
transition check for xtl_createlogger_stdiostream in a libxentoollog
library and use it if present. If it is not present assume it is in
libxenctrl.

Compile tested on Xen 4.6 and a development tree with the split in
place.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
I'm waiting on applying the upstream change until downstreams are
prepared for this. The latest upstream patch is
http://lists.xen.org/archives/html/xen-devel/2015-12/msg00454.html
which had to be reverted because I had somehow not properly checked if
libvirt used this interface
http://lists.xen.org/archives/html/xen-devel/2015-12/msg01153.html

It might be nice to get this into 1.3.0 so that supports Xen 4.7 out
of the box? Not sure what the libvirt stable backport policy is but it
might also be good to eventually consider it for that?

diff --git a/configure.ac b/configure.ac
index 98cf210b65b2024642a30aa7ef075334bb58ecde..b641cc707b6ab719d3962ebf1c79002757d2f31f 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -883,7 +883,6 @@ if test "$with_libxl" != "no" ; then
     PKG_CHECK_MODULES([LIBXL], [xenlight], [
      LIBXL_FIRMWARE_DIR=`$PKG_CONFIG --variable xenfirmwaredir xenlight`
      LIBXL_EXECBIN_DIR=`$PKG_CONFIG --variable libexec_bin xenlight`
-     LIBXL_LIBS="$LIBXL_LIBS -lxenctrl"
      with_libxl=yes
     ], [LIBXL_FOUND=no])
     if test "$LIBXL_FOUND" = "no"; then
@@ -896,7 +895,7 @@ if test "$with_libxl" != "no" ; then
         LIBS="$LIBS $LIBXL_LIBS"
         AC_CHECK_LIB([xenlight], [libxl_ctx_alloc], [
             with_libxl=yes
-            LIBXL_LIBS="$LIBXL_LIBS -lxenlight -lxenctrl"
+            LIBXL_LIBS="$LIBXL_LIBS -lxenlight"
         ],[
             if test "$with_libxl" = "yes"; then
                 fail=1
@@ -924,6 +923,14 @@ if test "$with_libxl" = "yes"; then
     if test "x$LIBXL_EXECBIN_DIR" != "x"; then
         AC_DEFINE_UNQUOTED([LIBXL_EXECBIN_DIR], ["$LIBXL_EXECBIN_DIR"], [directory containing Xen libexec binaries])
     fi
+    dnl Check if the xtl_* infrastructure is in libxentoollog
+    dnl (since Xen 4.7) if not then assume it is in libxenctrl
+    dnl (as it was for 4.6 and earler)
+    AC_CHECK_LIB([xentoollog], [xtl_createlogger_stdiostream], [
+        LIBXL_LIBS="$LIBXL_LIBS -lxentoollog"
+    ],[
+        LIBXL_LIBS="$LIBXL_LIBS -lxenctrl"
+    ])
 fi
 AM_CONDITIONAL([WITH_LIBXL], [test "$with_libxl" = "yes"])