# -*- autoconf -*-

# Copyright (c) 2008-2016, 2019 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
m4_include([m4/compat.m4])

dnl Checks for --enable-coverage and updates CFLAGS and LDFLAGS appropriately.
AC_DEFUN([OVS_CHECK_COVERAGE],
  [AC_REQUIRE([AC_PROG_CC])
   AC_ARG_ENABLE(
     [coverage],
     [AS_HELP_STRING([--enable-coverage],
                     [Enable gcov coverage tool.])],
     [case "${enableval}" in
        (yes) coverage=true ;;
        (no)  coverage=false ;;
        (*) AC_MSG_ERROR([bad value ${enableval} for --enable-coverage]) ;;
      esac],
     [coverage=false])
   if $coverage; then
     # Autoconf by default puts "-g -O2" in CFLAGS.  We need to remove the -O2
     # option for coverage to be useful.  This does it without otherwise
     # interfering with anything that the user might have put there.
     old_CFLAGS=$CFLAGS
     CFLAGS=
     for option in $old_CFLAGS; do
        case $option in
            (-O2) ;;
            (*) CFLAGS="$CFLAGS $option" ;;
        esac
     done

     OVS_CFLAGS="$OVS_CFLAGS --coverage"
     OVS_LDFLAGS="$OVS_LDFLAGS --coverage"
   fi])

dnl Checks for --enable-ndebug and defines NDEBUG if it is specified.
AC_DEFUN([OVS_CHECK_NDEBUG],
  [AC_ARG_ENABLE(
     [ndebug],
     [AS_HELP_STRING([--enable-ndebug],
                     [Disable debugging features for max performance])],
     [case "${enableval}" in
        (yes) ndebug=true ;;
        (no)  ndebug=false ;;
        (*) AC_MSG_ERROR([bad value ${enableval} for --enable-ndebug]) ;;
      esac],
     [ndebug=false])
   AM_CONDITIONAL([NDEBUG], [test x$ndebug = xtrue])])

dnl Checks for --enable-usdt-probes and defines HAVE_USDT if it is specified.
AC_DEFUN([OVS_CHECK_USDT], [
  AC_ARG_ENABLE(
    [usdt-probes],
    [AS_HELP_STRING([--enable-usdt-probes],
                    [Enable User Statically Defined Tracing (USDT) probes])],
    [case "${enableval}" in
       (yes) usdt=true ;;
       (no)  usdt=false ;;
       (*) AC_MSG_ERROR([bad value ${enableval} for --enable-usdt-probes]) ;;
     esac],
    [usdt=false])

  AC_MSG_CHECKING([whether USDT probes are enabled])
  if test "$usdt" != true; then
    AC_MSG_RESULT([no])
  else
    AC_MSG_RESULT([yes])

    AC_CHECK_HEADER([sys/sdt.h], [],
      [AC_MSG_ERROR([unable to find sys/sdt.h needed for USDT support])])

    AC_DEFINE([HAVE_USDT_PROBES], [1],
              [Define to 1 if USDT probes are enabled.])
  fi
  AM_CONDITIONAL([HAVE_USDT_PROBES], [test $usdt = true])
])

dnl Checks for MSVC x64 compiler.
AC_DEFUN([OVS_CHECK_WIN64],
  [AC_CACHE_CHECK(
    [for MSVC x64 compiler],
    [cl_cv_x64],
    [dnl "cl" writes x64 output to stdin:
     if (cl) 2>&1 | grep 'x64' >/dev/null 2>&1; then
       cl_cv_x64=yes
       MSVC64_LDFLAGS=" /MACHINE:X64 "
       MSVC_PLATFORM="x64"
     else
       cl_cv_x64=no
       MSVC64_LDFLAGS=""
       MSVC_PLATFORM="x86"
     fi])
     AC_SUBST([MSVC64_LDFLAGS])
     AC_SUBST([MSVC_PLATFORM])
])

dnl Checks for WINDOWS.
AC_DEFUN([OVS_CHECK_WIN32],
  [AC_CHECK_HEADER([windows.h],
                   [WIN32=yes],
                   [WIN32=no])
   AM_CONDITIONAL([WIN32], [test "$WIN32" = yes])
   if test "$WIN32" = yes; then
      AC_ARG_WITH([pthread],
         [AS_HELP_STRING([--with-pthread=DIR],
            [root of the pthread-win32 directory])],
         [
            case "$withval" in
            "" | y | ye | yes | n | no)
            AC_MSG_ERROR([Invalid --with-pthread value])
              ;;
            *)
            PTHREAD_WIN32_DIR=$withval/lib
            PTHREAD_WIN32_DIR_DLL=/$(echo ${withval} | ${SED} -e 's/://')/bin
            PTHREAD_WIN32_DIR_DLL_WIN_FORM=$withval/bin
            PTHREAD_INCLUDES=-I$withval/include
            PTHREAD_LDFLAGS=-L$PTHREAD_WIN32_DIR
            PTHREAD_LIBS="-lpthreadVC3"
            AC_SUBST([PTHREAD_WIN32_DIR_DLL_WIN_FORM])
            AC_SUBST([PTHREAD_WIN32_DIR_DLL])
            AC_SUBST([PTHREAD_INCLUDES])
            AC_SUBST([PTHREAD_LDFLAGS])
            AC_SUBST([PTHREAD_LIBS])
              ;;
            esac
         ], [
            AC_MSG_ERROR([pthread directory not specified])
         ]
      )
      AC_ARG_WITH([debug],
         [AS_HELP_STRING([--with-debug],
            [Build without compiler optimizations])],
         [
            MSVC_CFLAGS="-O0"
            AC_SUBST([MSVC_CFLAGS])
         ], [
            MSVC_CFLAGS="-O2"
            AC_SUBST([MSVC_CFLAGS])
         ]
      )

      AC_DEFINE([WIN32], [1], [Define to 1 if building on WIN32.])
      AC_CHECK_TYPES([struct timespec], [], [], [[#include <time.h>]])
      AH_BOTTOM([#ifdef WIN32
#include "include/windows/windefs.h"
#endif])
   fi])

dnl OVS_CHECK_WINDOWS
dnl
dnl Configure Visual Studio solution build
AC_DEFUN([OVS_CHECK_VISUAL_STUDIO_DDK], [
if test "$WIN32" = yes; then
  AC_ARG_WITH([vstudiotarget],
          [AS_HELP_STRING([--with-vstudiotarget=target_type],
              [Target type: Debug/Release])],
          [
              case "$withval" in
              "Release") ;;
              "Debug") ;;
              *) AC_MSG_ERROR([No valid Visual Studio configuration found]) ;;
              esac

              VSTUDIO_CONFIG=$withval
          ], [
              VSTUDIO_CONFIG="Debug"
          ]
        )

    AC_SUBST([VSTUDIO_CONFIG])

  AC_ARG_WITH([vstudiotargetver],
          [AS_HELP_STRING([--with-vstudiotargetver=target_ver1,target_ver2],
              [Target versions: Win8,Win8.1,Win10])],
          [
              targetver=`echo "$withval" | tr -s , ' ' `
              for ver in $targetver; do
                  case "$ver" in
                  "Win8") VSTUDIO_WIN8=true ;;
                  "Win8.1")  VSTUDIO_WIN8_1=true ;;
                  "Win10") VSTUDIO_WIN10=true ;;
                  *) AC_MSG_ERROR([No valid Visual Studio target version found]) ;;
                  esac
              done

          ], [
              VSTUDIO_WIN8=true
              VSTUDIO_WIN8_1=true
              VSTUDIO_WIN10=true
          ]
        )
    AC_DEFINE([VSTUDIO_DDK], [1], [System uses the Visual Studio build target.])
fi
AM_CONDITIONAL([VSTUDIO_WIN8], [test -n "$VSTUDIO_WIN8"])
AM_CONDITIONAL([VSTUDIO_WIN8_1], [test -n "$VSTUDIO_WIN8_1"])
AM_CONDITIONAL([VSTUDIO_WIN10], [test -n "$VSTUDIO_WIN10"])
AM_CONDITIONAL([VSTUDIO_DDK], [test -n "$VSTUDIO_CONFIG"])
])

dnl Checks for Netlink support.
AC_DEFUN([OVS_CHECK_NETLINK],
  [AC_CHECK_HEADER([linux/netlink.h],
                   [HAVE_NETLINK=yes],
                   [HAVE_NETLINK=no],
                   [#include <sys/socket.h>
   ])
   AM_CONDITIONAL([HAVE_NETLINK], [test "$HAVE_NETLINK" = yes])
   if test "$HAVE_NETLINK" = yes; then
      AC_DEFINE([HAVE_NETLINK], [1],
                [Define to 1 if Netlink protocol is available.])
   fi])

dnl Checks for libcap-ng.
AC_DEFUN([OVS_CHECK_LIBCAPNG],
  [AC_ARG_ENABLE(
     [libcapng],
     [AS_HELP_STRING([--disable-libcapng], [Disable Linux capability support])],
     [case "${enableval}" in
        (yes) libcapng=true ;;
        (no)  libcapng=false ;;
        (*) AC_MSG_ERROR([bad value ${enableval} for --enable-libcapng]) ;;
      esac],
     [libcapng=check])

   if test "$libcapng" != false; then
       AC_CHECK_LIB([cap-ng], [capng_clear], [HAVE_LIBCAPNG=yes])

       if test "$HAVE_LIBCAPNG" != yes; then
           if test "$libcapng" = true ; then
                AC_MSG_ERROR([libcap-ng support requested, but not found])
           fi
           if test "$libcapng" = check ; then
                 AC_MSG_WARN([cannot find libcap-ng.
--user option will not be supported on Linux.
(you may use --disable-libcapng to suppress this warning). ])
           fi
       fi
   fi

   AC_SUBST([HAVE_LIBCAPNG])
   AM_CONDITIONAL([HAVE_LIBCAPNG], [test "$HAVE_LIBCAPNG" = yes])
   if test "$HAVE_LIBCAPNG" = yes; then
      AC_DEFINE([HAVE_LIBCAPNG], [1],
                [Define to 1 if libcap-ng is available.])
      CAPNG_LDADD="-lcap-ng"
      AC_SUBST([CAPNG_LDADD])
   fi])

dnl Checks for OpenSSL.
AC_DEFUN([OVS_CHECK_OPENSSL],
  [AC_ARG_ENABLE(
     [ssl],
     [AS_HELP_STRING([--disable-ssl], [Disable OpenSSL support])],
     [case "${enableval}" in
        (yes) ssl=true ;;
        (no)  ssl=false ;;
        (*) AC_MSG_ERROR([bad value ${enableval} for --enable-ssl]) ;;
      esac],
     [ssl=check])

   if test "$ssl" != false; then
       AX_CHECK_OPENSSL(
         [HAVE_OPENSSL=yes],
         [HAVE_OPENSSL=no
          if test "$ssl" = check; then
            AC_MSG_WARN([Cannot find openssl:

$SSL_PKG_ERRORS

OpenFlow connections over SSL will not be supported.
(You may use --disable-ssl to suppress this warning.)])
          else
            AC_MSG_ERROR([Cannot find openssl (use --disable-ssl to configure without SSL support)])
          fi])
   else
       HAVE_OPENSSL=no
   fi
   AC_SUBST([HAVE_OPENSSL])
   AM_CONDITIONAL([HAVE_OPENSSL], [test "$HAVE_OPENSSL" = yes])
   if test "$HAVE_OPENSSL" = yes; then
      AC_DEFINE([HAVE_OPENSSL], [1], [Define to 1 if OpenSSL is installed.])
   fi

   OPENSSL_SUPPORTS_SNI=no
   if test $HAVE_OPENSSL = yes; then
      save_CPPFLAGS=$CPPFLAGS
      CPPFLAGS="$CPPFLAGS $SSL_INCLUDES"
      AC_CHECK_DECL([SSL_set_tlsext_host_name], [OPENSSL_SUPPORTS_SNI=yes],
                    [], [#include <openssl/ssl.h>
])
      if test $OPENSSL_SUPPORTS_SNI = yes; then
        AC_DEFINE(
          [OPENSSL_SUPPORTS_SNI], [1],
          [Define to 1 if OpenSSL supports Server Name Indication (SNI).])
      fi
      CPPFLAGS=$save_CPPFLAGS
   fi
   AC_SUBST([OPENSSL_SUPPORTS_SNI])
])

dnl Checks for libraries needed by lib/socket-util.c.
AC_DEFUN([OVS_CHECK_SOCKET_LIBS],
  [AC_CHECK_LIB([socket], [connect])
   AC_SEARCH_LIBS([gethostbyname], [resolv])])

dnl Checks for the directory in which to store the PKI.
AC_DEFUN([OVS_CHECK_PKIDIR],
  [AC_ARG_WITH(
     [pkidir],
     AS_HELP_STRING([--with-pkidir=DIR],
                    [PKI hierarchy directory [[LOCALSTATEDIR/lib/openvswitch/pki]]]),
     [PKIDIR=$withval],
     [PKIDIR='${localstatedir}/lib/openvswitch/pki'])
   AC_SUBST([PKIDIR])])

dnl Checks for the directory in which to store pidfiles.
AC_DEFUN([OVS_CHECK_RUNDIR],
  [AC_ARG_WITH(
     [rundir],
     AS_HELP_STRING([--with-rundir=DIR],
                    [directory used for pidfiles
                    [[LOCALSTATEDIR/run/openvswitch]]]),
     [RUNDIR=$withval],
     [RUNDIR='${localstatedir}/run/openvswitch'])
   AC_SUBST([RUNDIR])])

dnl Checks for the directory in which to store logs.
AC_DEFUN([OVS_CHECK_LOGDIR],
  [AC_ARG_WITH(
     [logdir],
     AS_HELP_STRING([--with-logdir=DIR],
                    [directory used for logs [[LOCALSTATEDIR/log/PACKAGE]]]),
     [LOGDIR=$withval],
     [LOGDIR='${localstatedir}/log/${PACKAGE}'])
   AC_SUBST([LOGDIR])])

dnl Checks for the directory in which to store the Open vSwitch database.
AC_DEFUN([OVS_CHECK_DBDIR],
  [AC_ARG_WITH(
     [dbdir],
     AS_HELP_STRING([--with-dbdir=DIR],
                    [directory used for conf.db [[SYSCONFDIR/PACKAGE]]]),
     [DBDIR=$withval],
     [DBDIR='${sysconfdir}/${PACKAGE}'])
   AC_SUBST([DBDIR])])

dnl Defines HAVE_BACKTRACE if backtrace() is found.
AC_DEFUN([OVS_CHECK_BACKTRACE],
  [AC_SEARCH_LIBS([backtrace], [execinfo ubacktrace],
                  [AC_DEFINE([HAVE_BACKTRACE], [1],
                             [Define to 1 if you have backtrace(3).])])])

dnl Defines HAVE_PERF_EVENT if linux/perf_event.h is found.
AC_DEFUN([OVS_CHECK_PERF_EVENT],
  [AC_CHECK_HEADERS([linux/perf_event.h])])

dnl Checks for valgrind/valgrind.h.
AC_DEFUN([OVS_CHECK_VALGRIND],
  [AC_CHECK_HEADERS([valgrind/valgrind.h])])

dnl Checks for Python 3.4 or later.
AC_DEFUN([OVS_CHECK_PYTHON3],
  [AC_CACHE_CHECK(
     [for Python 3 (version 3.4 or later)],
     [ovs_cv_python3],
     [if test -n "$PYTHON3"; then
        ovs_cv_python3=$PYTHON3
      else
        ovs_cv_python3=no
        for binary in python3 python3.4 python3.5 python3.6 python3.7; do
          ovs_save_IFS=$IFS; IFS=$PATH_SEPARATOR
          for dir in $PATH; do
            IFS=$ovs_save_IFS
            test -z "$dir" && dir=.
            if test -x "$dir"/"$binary" && "$dir"/"$binary" -c 'import sys
if sys.hexversion >= 0x03040000 and sys.hexversion < 0x04000000:
    sys.exit(0)
else:
    sys.exit(1)'; then
              ovs_cv_python3=$dir/$binary
              break 2
            fi
          done
        done
      fi])
   if test "$ovs_cv_python3" = no; then
     AC_MSG_ERROR([Python 3.4 or later is required but not found in $PATH, please install it or set $PYTHON3 to point to it])
   fi
   AC_ARG_VAR([PYTHON3])
   PYTHON3=$ovs_cv_python3])

dnl Checks for flake8.
AC_DEFUN([OVS_CHECK_FLAKE8],
  [AC_CACHE_CHECK(
    [for flake8],
    [ovs_cv_flake8],
    [if flake8 --version >/dev/null 2>&1; then
       ovs_cv_flake8=yes
     else
       ovs_cv_flake8=no
     fi])
   AM_CONDITIONAL([HAVE_FLAKE8], [test "$ovs_cv_flake8" = yes])])

dnl Checks for sphinx.
AC_DEFUN([OVS_CHECK_SPHINX],
  [AC_CHECK_PROGS(
     [SPHINXBUILD], [sphinx-build-3 sphinx-build-2 sphinx-build], [none])
   AC_ARG_VAR([SPHINXBUILD])
   AM_CONDITIONAL([HAVE_SPHINX], [test "$SPHINXBUILD" != none])])


dnl Checks for compiler correctly emitting AVX512-VL vpermd instruction.
dnl GCC5 says it exports AVX512-VL, but it doesn't implement "vpermd" instruction
dnl resulting in compilation failures. To workaround this "reported vs actual"
dnl mismatch, we compile a small snippet, and conditionally enable AVX512-VL.
AC_DEFUN([OVS_CHECK_GCC_AVX512VL], [
  AC_MSG_CHECKING([whether compiler correctly emits AVX512-VL])
  AC_COMPILE_IFELSE(
    [AC_LANG_PROGRAM([#include <immintrin.h>
                     static void __attribute__((__target__("avx512vl")))
                     check_permutexvar(void)
                     {
                         __m256i v_swap32a = _mm256_setr_epi32(0x0, 0x4, 0xF,
                                                               0xF, 0xF, 0xF,
                                                               0xF, 0xF);
                         v_swap32a = _mm256_permutexvar_epi32(v_swap32a,
                                                              v_swap32a);
                     }],[])],
    [AC_MSG_RESULT([yes])
    ovs_cv_gcc_avx512vl_good=yes],
    [AC_MSG_RESULT([no])
    ovs_cv_gcc_avx512vl_good=no])
   if test "$ovs_cv_gcc_avx512vl_good" = yes; then
     AC_DEFINE([HAVE_GCC_AVX512VL_GOOD], [1],
               [Define to 1 if gcc implements the vpermd instruction.])
   fi
   AM_CONDITIONAL([HAVE_GCC_AVX512VL_GOOD],
                  [test "$ovs_cv_gcc_avx512vl_good" = yes])])

dnl Checks whether the build system implements the vpopcntdq instruction. The
dnl compiler and assembler each separately need to support vpopcntdq. In order
dnl to test the assembler with the below code snippet, set the optimization
dnl level of the function to "O0" so it won't be optimized away by the
dnl compiler.
AC_DEFUN([OVS_CHECK_AVX512VPOPCNTDQ], [
  AC_MSG_CHECKING([whether compiler correctly emits AVX512-VPOPCNTDQ])
  AC_COMPILE_IFELSE(
    [AC_LANG_PROGRAM([#include <immintrin.h>
                     void
                     __attribute__((__target__("avx512vpopcntdq")))
                     __attribute__((optimize("O0")))
                     check_vpopcntdq(void)
                     {
                         __m512i v_test;
                         v_test = _mm512_popcnt_epi64(v_test);
                     }],[])],
    [AC_MSG_RESULT([yes])
    ovs_cv_avx512vpopcntdq_good=yes],
    [AC_MSG_RESULT([no])
    ovs_cv_avx512vpopcntdq_good=no])
   if test "$ovs_cv_avx512vpopcntdq_good" = yes; then
     AC_DEFINE([HAVE_AVX512VPOPCNTDQ], [1],
               [Define to 1 if the build system implements the vpopcntdq
                instruction.])
   fi
   AM_CONDITIONAL([HAVE_AVX512VPOPCNTDQ],
                  [test "$ovs_cv_avx512vpopcntdq_good" = yes])])

dnl Checks for binutils/assembler known issue with AVX512.
dnl Due to backports, we probe assembling a reproducer instead of checking
dnl binutils version string. More details, including ASM dumps and debug here:
dnl   GCC: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90028
dnl The checking of binutils funcationality instead of LD version is similar
dnl to as how DPDK proposes to solve this issue:
dnl   http://patches.dpdk.org/patch/71723/
AC_DEFUN([OVS_CHECK_BINUTILS_AVX512],
  [AC_CACHE_CHECK(
    [binutils avx512 assembler checks passing],
    [ovs_cv_binutils_avx512_good],
    [dnl Assemble a short snippet to test for issue in "build-aux" dir:
     mkdir -p build-aux
     OBJFILE=build-aux/binutils_avx512_check.o
     GATHER_PARAMS='0x8(,%ymm1,1),%ymm0{%k2}'
     if ($CC -dumpmachine | grep x86_64) >/dev/null 2>&1; then
       echo "vpgatherqq $GATHER_PARAMS" | as --64 -o $OBJFILE -
       if (objdump -d  --no-show-raw-insn $OBJFILE | grep -q $GATHER_PARAMS) >/dev/null 2>&1; then
         ovs_cv_binutils_avx512_good=yes
       else
         ovs_cv_binutils_avx512_good=no
         dnl Explicitly disallow avx512f to stop compiler auto-vectorizing
         dnl and causing zmm usage with buggy binutils versions.
         CFLAGS="$CFLAGS -mno-avx512f"
       fi
       rm $OBJFILE
     else
       dnl non x86_64 architectures don't have avx512, so not affected
       ovs_cv_binutils_avx512_good=no
     fi])
   if test "$ovs_cv_binutils_avx512_good" = yes; then
     AC_DEFINE([HAVE_LD_AVX512_GOOD], [1],
               [Define to 1 if binutils correctly supports AVX512.])
   fi
   AM_CONDITIONAL([HAVE_LD_AVX512_GOOD],
                  [test "$ovs_cv_binutils_avx512_good" = yes])])

dnl Checks for dot.
AC_DEFUN([OVS_CHECK_DOT],
  [AC_CACHE_CHECK(
    [for dot],
    [ovs_cv_dot],
    [dnl "dot" writes -V output to stderr:
     if (dot -V) 2>&1 | grep '^dot - [[gG]]raphviz version' >/dev/null 2>&1; then
       ovs_cv_dot=yes
     else
       ovs_cv_dot=no
     fi])
   AM_CONDITIONAL([HAVE_DOT], [test "$ovs_cv_dot" = yes])])

dnl Checks for groff.
AC_DEFUN([OVS_CHECK_GROFF],
  [AC_CACHE_CHECK(
    [for groff],
    [ovs_cv_groff],
    [if (groff -v) >/dev/null 2>&1; then
       ovs_cv_groff=yes
     else
       ovs_cv_groff=no
     fi])
   AM_CONDITIONAL([HAVE_GROFF], [test "$ovs_cv_groff" = yes])])

dnl Checks for thread-local storage support.
dnl
dnl Checks whether the compiler and linker support the C11
dnl thread_local macro from <threads.h>, and if so defines
dnl HAVE_THREAD_LOCAL.  If not, checks whether the compiler and linker
dnl support the GCC __thread extension, and if so defines
dnl HAVE___THREAD.
AC_DEFUN([OVS_CHECK_TLS],
  [AC_CACHE_CHECK(
     [whether $CC has <threads.h> that supports thread_local],
     [ovs_cv_thread_local],
     [AC_LINK_IFELSE(
        [AC_LANG_PROGRAM([#include <threads.h>
static thread_local int var;], [return var;])],
        [ovs_cv_thread_local=yes],
        [ovs_cv_thread_local=no])])
   if test $ovs_cv_thread_local = yes; then
     AC_DEFINE([HAVE_THREAD_LOCAL], [1],
               [Define to 1 if the C compiler and linker supports the C11
                thread_local matcro defined in <threads.h>.])
   else
     AC_CACHE_CHECK(
       [whether $CC supports __thread],
       [ovs_cv___thread],
       [AC_LINK_IFELSE(
          [AC_LANG_PROGRAM([static __thread int var;], [return var;])],
          [ovs_cv___thread=yes],
          [ovs_cv___thread=no])])
     if test $ovs_cv___thread = yes; then
       AC_DEFINE([HAVE___THREAD], [1],
                 [Define to 1 if the C compiler and linker supports the
                  GCC __thread extenions.])
     fi
   fi])

dnl OVS_CHECK_ATOMIC_LIBS
dnl
dnl Check to see if -latomic is need for GCC atomic built-ins.
AC_DEFUN([OVS_CHECK_ATOMIC_LIBS],
   [AC_SEARCH_LIBS([__atomic_load_8], [atomic])])

dnl OVS_CHECK_GCC4_ATOMICS
dnl
dnl Checks whether the compiler and linker support GCC 4.0+ atomic built-ins.
dnl A compile-time only check is not enough because the compiler defers
dnl unimplemented built-ins to libgcc, which sometimes also lacks
dnl implementations.
AC_DEFUN([OVS_CHECK_GCC4_ATOMICS],
  [AC_CACHE_CHECK(
     [whether $CC supports GCC 4.0+ atomic built-ins],
     [ovs_cv_gcc4_atomics],
     [AC_LINK_IFELSE(
        [AC_LANG_PROGRAM([[#include <stdlib.h>

#define ovs_assert(expr) if (!(expr)) abort();
#define TEST_ATOMIC_TYPE(TYPE)                  \
    {                                           \
        TYPE x = 1;                             \
        TYPE orig;                              \
                                                \
        __sync_synchronize();                   \
        ovs_assert(x == 1);                     \
                                                \
        __sync_synchronize();                   \
        x = 3;                                  \
        __sync_synchronize();                   \
        ovs_assert(x == 3);                     \
                                                \
        orig = __sync_fetch_and_add(&x, 1);     \
        ovs_assert(orig == 3);                  \
        __sync_synchronize();                   \
        ovs_assert(x == 4);                     \
                                                \
        orig = __sync_fetch_and_sub(&x, 2);     \
        ovs_assert(orig == 4);                  \
        __sync_synchronize();                   \
        ovs_assert(x == 2);                     \
                                                \
        orig = __sync_fetch_and_or(&x, 6);      \
        ovs_assert(orig == 2);                  \
        __sync_synchronize();                   \
        ovs_assert(x == 6);                     \
                                                \
        orig = __sync_fetch_and_and(&x, 10);    \
        ovs_assert(orig == 6);                  \
        __sync_synchronize();                   \
        ovs_assert(x == 2);                     \
                                                \
        orig = __sync_fetch_and_xor(&x, 10);    \
        ovs_assert(orig == 2);                  \
        __sync_synchronize();                   \
        ovs_assert(x == 8);                     \
    }]], [dnl
TEST_ATOMIC_TYPE(char);
TEST_ATOMIC_TYPE(unsigned char);
TEST_ATOMIC_TYPE(signed char);
TEST_ATOMIC_TYPE(short);
TEST_ATOMIC_TYPE(unsigned short);
TEST_ATOMIC_TYPE(int);
TEST_ATOMIC_TYPE(unsigned int);
TEST_ATOMIC_TYPE(long int);
TEST_ATOMIC_TYPE(unsigned long int);
TEST_ATOMIC_TYPE(long long int);
TEST_ATOMIC_TYPE(unsigned long long int);
])],
        [ovs_cv_gcc4_atomics=yes],
        [ovs_cv_gcc4_atomics=no])])
   if test $ovs_cv_gcc4_atomics = yes; then
     AC_DEFINE([HAVE_GCC4_ATOMICS], [1],
               [Define to 1 if the C compiler and linker supports the GCC 4.0+
                atomic built-ins.])
   fi])

dnl OVS_CHECK_ATOMIC_ALWAYS_LOCK_FREE(SIZE)
dnl
dnl Checks __atomic_always_lock_free(SIZE, 0)
AC_DEFUN([OVS_CHECK_ATOMIC_ALWAYS_LOCK_FREE],
  [AC_CACHE_CHECK(
    [value of __atomic_always_lock_free($1)],
    [ovs_cv_atomic_always_lock_free_$1],
    [AC_COMPUTE_INT(
        [ovs_cv_atomic_always_lock_free_$1],
        [__atomic_always_lock_free($1, 0)],
        [],
        [ovs_cv_atomic_always_lock_free_$1=unsupported])])
   if test ovs_cv_atomic_always_lock_free_$1 != unsupported; then
     AC_DEFINE_UNQUOTED(
       [ATOMIC_ALWAYS_LOCK_FREE_$1B],
       [$ovs_cv_atomic_always_lock_free_$1],
       [If the C compiler is GCC 4.7 or later, define to the return value of
        __atomic_always_lock_free($1, 0).  If the C compiler is not GCC or is
        an older version of GCC, the value does not matter.])
   fi])

dnl OVS_CHECK_POSIX_AIO
AC_DEFUN([OVS_CHECK_POSIX_AIO],
  [AC_SEARCH_LIBS([aio_write], [rt])
   AM_CONDITIONAL([HAVE_POSIX_AIO], [test "$ac_cv_search_aio_write" != no])])

dnl OVS_CHECK_INCLUDE_NEXT
AC_DEFUN([OVS_CHECK_INCLUDE_NEXT],
  [AC_REQUIRE([gl_CHECK_NEXT_HEADERS])
   gl_CHECK_NEXT_HEADERS([$1])])

dnl OVS_CHECK_PRAGMA_MESSAGE
AC_DEFUN([OVS_CHECK_PRAGMA_MESSAGE],
  [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
   [[_Pragma("message(\"Checking for pragma message\")")
   ]])],
     [AC_DEFINE(HAVE_PRAGMA_MESSAGE,1,[Define if compiler supports #pragma
     message directive])])
  ])

dnl OVS_LIBTOOL_VERSIONS sets the major, minor, micro version information for
dnl OVS_LTINFO variable.  This variable locks libtool information for shared
dnl objects, allowing multiple versions with different ABIs to coexist.
AC_DEFUN([OVS_LIBTOOL_VERSIONS],
    [AC_MSG_CHECKING(linker output version information)
  OVS_MAJOR=`echo "$PACKAGE_VERSION" | sed -e 's/[[.]].*//'`
  OVS_MINOR=`echo "$PACKAGE_VERSION" | sed -e "s/^$OVS_MAJOR//" -e 's/^.//' -e 's/[[.]].*//'`
  OVS_MICRO=`echo "$PACKAGE_VERSION" | sed -e "s/^$OVS_MAJOR.$OVS_MINOR//" -e 's/^.//' -e 's/[[^0-9]].*//'`
  OVS_LT_RELINFO="-release $OVS_MAJOR.$OVS_MINOR"
  OVS_LT_VERINFO="-version-info $LT_CURRENT:$OVS_MICRO"
  OVS_LTINFO="$OVS_LT_RELINFO $OVS_LT_VERINFO"
  AC_MSG_RESULT([libX-$OVS_MAJOR.$OVS_MINOR.so.$LT_CURRENT.0.$OVS_MICRO)])
  AC_SUBST(OVS_LTINFO)
    ])

dnl OVS does not use C++ itself, but it provides public header files
dnl that a C++ compiler should accept, so when --enable-Werror is in
dnl effect and a C++ compiler is available, we enable building a C++
dnl source file that #includes all the public headers, as a way to
dnl ensure that they are acceptable as C++.
AC_DEFUN([OVS_CHECK_CXX],
  [AC_REQUIRE([AC_PROG_CXX])
   AC_REQUIRE([OVS_ENABLE_WERROR])
   AX_CXX_COMPILE_STDCXX([11], [], [optional])
   if test $enable_Werror = yes && test $HAVE_CXX11 = 1; then
     enable_cxx=:
     AC_LANG_PUSH([C++])
     AC_CHECK_HEADERS([atomic])
     AC_LANG_POP([C++])
   else
     enable_cxx=false
   fi
   AM_CONDITIONAL([HAVE_CXX], [$enable_cxx])])

dnl Checks for unbound library.
AC_DEFUN([OVS_CHECK_UNBOUND],
  [AC_CHECK_LIB(unbound, ub_ctx_create, [HAVE_UNBOUND=yes], [HAVE_UNBOUND=no])
   if test "$HAVE_UNBOUND" = yes; then
     AC_DEFINE([HAVE_UNBOUND], [1], [Define to 1 if unbound is detected.])
     LIBS="$LIBS -lunbound"
   fi
   AM_CONDITIONAL([HAVE_UNBOUND], [test "$HAVE_UNBOUND" = yes])
   AC_SUBST([HAVE_UNBOUND])])

dnl Checks for libunwind.
AC_DEFUN([OVS_CHECK_UNWIND],
  [AC_CHECK_LIB([unwind], [unw_backtrace],
   [AC_CHECK_HEADERS([libunwind.h], [HAVE_UNWIND=yes], [HAVE_UNWIND=no])],
   [HAVE_UNWIND=no])
   if test "$HAVE_UNWIND" = yes; then
     AC_DEFINE([HAVE_UNWIND], [1], [Define to 1 if unwind is detected.])
     LIBS="$LIBS -lunwind"
   fi
   AM_CONDITIONAL([HAVE_UNWIND], [test "$HAVE_UNWIND" = yes])
   AC_SUBST([HAVE_UNWIND])])