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78 lines
2.5 KiB
Plaintext
78 lines
2.5 KiB
Plaintext
dnl The atomic implementation check
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dnl
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dnl Copyright (C) 2016 Red Hat, Inc.
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dnl
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dnl This library is free software; you can redistribute it and/or
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dnl modify it under the terms of the GNU Lesser General Public
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dnl License as published by the Free Software Foundation; either
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dnl version 2.1 of the License, or (at your option) any later version.
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dnl
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dnl This library is distributed in the hope that it will be useful,
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dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
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dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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dnl Lesser General Public License for more details.
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dnl
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dnl You should have received a copy of the GNU Lesser General Public
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dnl License along with this library. If not, see
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dnl <http://www.gnu.org/licenses/>.
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dnl
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AC_DEFUN([LIBVIRT_CHECK_ATOMIC], [
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AC_REQUIRE([LIBVIRT_CHECK_PTHREAD])
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dnl We need to decide at configure time if libvirt will use real atomic
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dnl operations ("lock free") or emulated ones with a mutex.
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dnl
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dnl Note that the atomic ops are only available with GCC on x86 when
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dnl using -march=i486 or higher. If we detect that the atomic ops are
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dnl not available but would be available given the right flags, we want
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dnl to abort and advise the user to fix their CFLAGS. It's better to do
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dnl that then to silently fall back on emulated atomic ops just because
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dnl the user had the wrong build environment.
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atomic_ops=
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AC_MSG_CHECKING([for atomic ops implementation])
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AC_TRY_COMPILE([], [__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4;],[
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atomic_ops=gcc
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],[])
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if test "$atomic_ops" = "" ; then
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SAVE_CFLAGS="${CFLAGS}"
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CFLAGS="-march=i486"
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AC_TRY_COMPILE([],
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[__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4;],
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[AC_MSG_ERROR([Libvirt must be built with -march=i486 or later.])],
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[])
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CFLAGS="${SAVE_CFLAGS}"
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case "$host" in
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*-*-mingw* | *-*-msvc* )
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atomic_ops=win32
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;;
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*)
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if test "$ac_cv_header_pthread_h" = "yes" ; then
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atomic_ops=pthread
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else
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AC_MSG_ERROR([Libvirt must be built with GCC or have pthread.h on non-Win32 platforms])
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fi
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;;
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esac
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fi
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case "$atomic_ops" in
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gcc)
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AC_DEFINE([VIR_ATOMIC_OPS_GCC],[1],[Use GCC atomic ops])
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;;
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win32)
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AC_DEFINE([VIR_ATOMIC_OPS_WIN32],[1],[Use Win32 atomic ops])
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;;
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pthread)
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AC_DEFINE([VIR_ATOMIC_OPS_PTHREAD],[1],[Use pthread atomic ops emulation])
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;;
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esac
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AM_CONDITIONAL([WITH_ATOMIC_OPS_PTHREAD],[test "$atomic_ops" = "pthread"])
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AC_MSG_RESULT([$atomic_ops])
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])
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