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6aca012)
The dmb instruction is used to implement a memory barrier on modern
ARM hardware. The older generations of processors which are included
in single processor systems can get by on the generic implementation
of the cmm_mb(). This will allow the user space rcu to work on many
other ARM systems.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
AH_TEMPLATE([CONFIG_RCU_HAVE_FUTEX], [Defined when on a system with futex support.])
AH_TEMPLATE([CONFIG_RCU_COMPAT_ARCH], [Compatibility mode for i386 which lacks
cmpxchg instruction.])
AH_TEMPLATE([CONFIG_RCU_HAVE_FUTEX], [Defined when on a system with futex support.])
AH_TEMPLATE([CONFIG_RCU_COMPAT_ARCH], [Compatibility mode for i386 which lacks
cmpxchg instruction.])
+AH_TEMPLATE([CONFIG_ARM_HAVE_DMB], [Use the dmb instruction is available for use on ARM.])
# Checks for programs.
AC_PROG_CC
# Checks for programs.
AC_PROG_CC
*) ARCHTYPE="unknown";;
esac
*) ARCHTYPE="unknown";;
esac
+if test "x$ARCHTYPE" = "xarm" ; then
+AC_MSG_CHECKING([checking for dmb instruction])
+AC_TRY_COMPILE(
+[
+],
+[
+asm volatile("dmb":::"memory");
+],
+[
+ AC_MSG_RESULT([yes])
+ AC_DEFINE([CONFIG_ARM_HAVE_DMB], [1])
+]
+,
+[
+ AC_MSG_RESULT([no])
+]
+)
+fi
+
UATOMICSRC=urcu/uatomic_arch_$ARCHTYPE.h
ARCHSRC=urcu/arch_$ARCHTYPE.h
if test "x$ARCHTYPE" != xx86 -a "x$ARCHTYPE" != xppc; then
UATOMICSRC=urcu/uatomic_arch_$ARCHTYPE.h
ARCHSRC=urcu/arch_$ARCHTYPE.h
if test "x$ARCHTYPE" != xx86 -a "x$ARCHTYPE" != xppc; then
+#ifdef CONFIG_ARM_HAVE_DMB
#define cmm_mb() asm volatile("dmb":::"memory")
#define cmm_mb() asm volatile("dmb":::"memory")
+#endif /* CONFIG_ARM_HAVE_DMB */
#include <stdlib.h>
#include <sys/time.h>
#include <stdlib.h>
#include <sys/time.h>