autoconf: add libnl3 dependency for Remus network buffering support

Libnl3 is required for controlling Remus network buffering.
This patch adds dependency on libnl3 (>= 3.2.8) to autoconf scripts.
It also provides the ability to configure tools without libnl3 support
i.e., without network buffering support.

When there is no network buffering support, libxl__netbuffer_enabled()
returns 0, otherwise returns 1. The callers of this api will be
introduced in the rest of the series.

NOTE: This patch changes tools/configure.ac, please rerun
      autogen.sh while applying the patch.

Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

README

@@ -73,6 +73,10 @@ disabled at compile time:
     * markdown
     * figlet (for generating the traditional Xen start of day banner)
     * systemd daemon development files
+    * Development install of libnl3 (e.g., libnl-3-200,
+      libnl-3-dev, etc).  Required if network buffering is desired
+      when using Remus with libxl.  See tools/remus/README for detailed
+      information.
 
 Second, you need to acquire a suitable kernel for use in domain 0. If
 possible you should use a kernel provided by your OS distributor. If

config/Tools.mk.in

@@ -43,6 +43,9 @@ PTHREAD_LIBS        := @PTHREAD_LIBS@
 
 PTYFUNCS_LIBS       := @PTYFUNCS_LIBS@
 
+LIBNL3_LIBS         := @LIBNL3_LIBS@
+LIBNL3_CFLAGS       := @LIBNL3_CFLAGS@
+
 # Download GIT repositories via HTTP or GIT's own protocol?
 # GIT's protocol is faster and more robust, when it works at all (firewalls
 # may block it). We make it the default, but if your GIT repository downloads
@@ -62,6 +65,7 @@ CONFIG_BLKTAP1      := @blktap1@
 CONFIG_BLKTAP2      := @blktap2@
 CONFIG_VTPM         := @vtpm@
 CONFIG_QEMUU_EXTRA_ARGS:= @EXTRA_QEMUU_CONFIGURE_ARGS@
+CONFIG_REMUS_NETBUF := @remus_netbuf@
 
 CONFIG_SYSTEMD      := @systemd@
 SYSTEMD_CFLAGS      := @SYSTEMD_CFLAGS@

docs/README.remus

@@ -2,3 +2,9 @@ Remus provides fault tolerance for virtual machines by sending continuous
 checkpoints to a backup, which will activate if the target VM fails.
 
 See the website at http://wiki.xen.org/wiki/Remus for details.
+
+Using Remus with libxl on Xen 4.5 and higher:
+ To enable network buffering, you need libnl 3.2.8
+ or higher along with the development headers and command line utilities.
+ If your distro does not have the appropriate libnl3 version, you can find
+ the latest source tarball of libnl3 at http://www.carisma.slowglass.com/~tgr/libnl/

tools/configure.ac

@@ -320,6 +320,22 @@ esac
 # Checks for header files.
 AC_CHECK_HEADERS([yajl/yajl_version.h sys/eventfd.h valgrind/memcheck.h utmp.h])
 
+# Check for libnl3 >=3.2.8. If present enable remus network buffering.
+PKG_CHECK_MODULES(LIBNL3, [libnl-3.0 >= 3.2.8 libnl-route-3.0 >= 3.2.8],
+    [libnl3_lib="y"], [libnl3_lib="n"])
+
+AS_IF([test "x$libnl3_lib" = "xn" ], [
+    AC_MSG_WARN([Disabling support for Remus network buffering.
+    Please install libnl3 libraries, command line tools and devel
+    headers - version 3.2.8 or higher])
+    AC_SUBST(remus_netbuf, [n])
+    ],[
+    AC_SUBST(remus_netbuf, [y])
+])
+
+AC_SUBST(LIBNL3_LIBS)
+AC_SUBST(LIBNL3_CFLAGS)
+
 fi # ! $rump
 
 AX_AVAILABLE_SYSTEMD()

tools/libxl/Makefile

@@ -21,11 +21,17 @@ endif
 
 LIBXL_LIBS =
 LIBXL_LIBS = $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) $(LDLIBS_libxenstore) $(LDLIBS_libblktapctl) $(PTYFUNCS_LIBS) $(LIBUUID_LIBS)
+ifeq ($(CONFIG_REMUS_NETBUF),y)
+LIBXL_LIBS += $(LIBNL3_LIBS)
+endif
 
 CFLAGS_LIBXL += $(CFLAGS_libxenctrl)
 CFLAGS_LIBXL += $(CFLAGS_libxenguest)
 CFLAGS_LIBXL += $(CFLAGS_libxenstore)
 CFLAGS_LIBXL += $(CFLAGS_libblktapctl) 
+ifeq ($(CONFIG_REMUS_NETBUF),y)
+CFLAGS_LIBXL += $(LIBNL3_CFLAGS)
+endif
 CFLAGS_LIBXL += -Wshadow
 
 LIBXL_LIBS-$(CONFIG_ARM) += -lfdt
@@ -43,6 +49,13 @@ LIBXL_OBJS-y += libxl_blktap2.o
 else
 LIBXL_OBJS-y += libxl_noblktap2.o
 endif
+
+ifeq ($(CONFIG_REMUS_NETBUF),y)
+LIBXL_OBJS-y += libxl_netbuffer.o
+else
+LIBXL_OBJS-y += libxl_nonetbuffer.o
+endif
+
 LIBXL_OBJS-$(CONFIG_X86) += libxl_cpuid.o libxl_x86.o
 LIBXL_OBJS-$(CONFIG_ARM) += libxl_nocpuid.o libxl_arm.o
 

tools/libxl/libxl_internal.h

@@ -2586,6 +2586,7 @@ typedef struct libxl__save_helper_state {
                       * marshalling and xc callback functions */
 } libxl__save_helper_state;
 
+_hidden int libxl__netbuffer_enabled(libxl__gc *gc);
 
 /*----- Domain suspend (save) state structure -----*/
 

tools/libxl/libxl_netbuffer.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014
+ * Author Shriram Rajagopalan <rshriram@cs.ubc.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include "libxl_osdeps.h" /* must come before any other headers */
+
+#include "libxl_internal.h"
+
+int libxl__netbuffer_enabled(libxl__gc *gc)
+{
+    return 1;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */

tools/libxl/libxl_nonetbuffer.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014
+ * Author Shriram Rajagopalan <rshriram@cs.ubc.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include "libxl_osdeps.h" /* must come before any other headers */
+
+#include "libxl_internal.h"
+
+int libxl__netbuffer_enabled(libxl__gc *gc)
+{
+    return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */