+# Use compiler Thread Local Storage, when disabled use pthread_getspecific() to emulate TLS.
+# Enabled by default
+AE_FEATURE_DEFAULT_ENABLE
+AE_FEATURE([compiler-tls], [Use pthread_getspecific() to emulate Thread Local Storage (TLS) variables.])
+
+# smp-support configure option
+# Enabled by default
+AE_FEATURE_DEFAULT_ENABLE
+AE_FEATURE([smp-support], [Disable SMP support. Warning: only use this on uniprocessor systems.])
+
+# RCU debugging option
+# Disabled by default
+AE_FEATURE_DEFAULT_DISABLE
+AE_FEATURE([rcu-debug], [Enable internal debugging self-checks. Introduces a performance penalty.])
+
+# rculfhash iterator debugging
+# Disabled by default
+AE_FEATURE_DEFAULT_DISABLE
+AE_FEATURE([cds-lfht-iter-debug], [Enable extra debugging checks for lock-free hash table iterator traversal. Alters the rculfhash ABI. Make sure to compile both library and application with matching configuration.])
+
+
+## ##
+## Set defines for optional features conditionnals in the source code ##
+## ##
+
+AE_IF_FEATURE_DISABLED([sys-membarrier-fallback], [
+ AC_DEFINE([CONFIG_RCU_FORCE_SYS_MEMBARRIER], [1], [Require the operating system to support the membarrier system call for default and bulletproof flavors.])
+])
+
+AE_IF_FEATURE_ENABLED([compiler-tls], [
+ AC_DEFINE([CONFIG_RCU_TLS], [1], [Use compiler provided Thread Local Storage.])
+])
+
+AE_IF_FEATURE_ENABLED([smp-support], [
+ AC_DEFINE([CONFIG_RCU_SMP], [1], [Enable SMP support. With SMP support enabled, uniprocessors are also supported. With SMP support disabled, UP systems work fine, but the behavior of SMP systems is undefined.])
+])
+
+AE_IF_FEATURE_ENABLED([rcu-debug], [
+ AC_DEFINE([CONFIG_RCU_DEBUG], [1], [Enable internal debugging self-checks. Introduces a performance penalty.])
+])
+
+AE_IF_FEATURE_ENABLED([cds-lfht-iter-debug], [
+ AC_DEFINE([CONFIG_CDS_LFHT_ITER_DEBUG], [1], [Enable extra debugging checks for lock-free hash table iterator traversal. Alters the rculfhash ABI. Make sure to compile both library and application with matching configuration.])
+])
+
+
+# From the sched_setaffinity(2)'s man page:
+# ~~~~
+# The CPU affinity system calls were introduced in Linux kernel 2.5.8.
+# The library interfaces were introduced in glibc 2.3. Initially, the
+# glibc interfaces included a cpusetsize argument. In glibc 2.3.3,
+# the cpuset size argument was removed, but this argument was
+# restored in glibc 2.3.4.
+# ~~~~
+
+# In addition to that, some vendors ported the system call to 2.4
+# kernels.
+
+# Furthermore, when the function first appeared, the MASK argument was
+# an unsigned long pointer, while later it was made into a cpu_set_t
+# pointer. Systems that have the cpu_set_t version also should have
+# the CPU_ZERO, CPU_SET, etc. macros.
+
+# All this mess means we have to cater for at least 3 different
+# sched_setaffinity prototypes:
+
+# ~~~~
+# int sched_setaffinity (pid_t pid, unsigned int len, unsigned long *mask);
+# int sched_setaffinity (pid_t __pid, size_t __cpusetsize, const cpu_set_t *__cpuset);
+# int sched_setaffinity (pid_t __pid, const cpu_set_t *__mask);
+# ~~~~
+
+AC_CHECK_TYPES([cpu_set_t],
+ [have_cpu_set_t="yes"],
+ [have_cpu_set_t="no"],
+ [#include <sched.h>])
+
+# Confirm that we have CPU_ZERO, and it actually works.
+AC_MSG_CHECKING([whether CPU_ZERO works])
+AH_TEMPLATE([HAVE_CPU_ZERO], [Defined to 1 if we have CPU_ZERO and it works])
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+ #include <sched.h>
+ int main()
+ {
+ cpu_set_t foo; CPU_ZERO(&foo);
+ return 0;
+ }
+ ]])
+],[
+ AC_DEFINE(HAVE_CPU_ZERO, 1)
+ AC_MSG_RESULT([yes])
+],[
+ AC_MSG_RESULT([no])
+])
+
+# Confirm that we have CPU_SET, and it actually works.
+AC_MSG_CHECKING([whether CPU_SET works])
+AH_TEMPLATE([HAVE_CPU_SET], [Defined to 1 if we have CPU_SET and it works])
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+ #include <sched.h>
+ int main()
+ {
+ cpu_set_t foo; CPU_SET(0, &foo);
+ return 0;
+ }
+ ]])
+],[
+ AC_DEFINE(HAVE_CPU_SET, 1)
+ AC_MSG_RESULT([yes])
+],[
+ AC_MSG_RESULT([no])
+])
+
+# First check if the function is available at all.
+AC_CHECK_FUNCS([sched_setaffinity],[
+ # Okay, we have it. Check if also have cpu_set_t. If we don't,
+ # then we have the first version using unsigned long, and no
+ # CPU_ZERO, etc. macros. If we do have cpu_set_t, we may have the
+ # version with 2 or 3 arguments. In that case, CPU_ZERO, etc.,
+ # should also be present, but we confirm nonetheless.
+
+ AS_IF([test "x$have_cpu_set_t" = "xyes"], [
+ # We do have it.
+ # Check how many arguments does sched_setaffinity take.
+ # Should be 3 or 2.
+ AC_MSG_CHECKING([how many arguments sched_setaffinity takes])
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+ #include <sched.h>
+ int main()
+ {
+ cpu_set_t foo;
+ sched_setaffinity(0, sizeof (foo), &foo);
+ return 0;
+ }
+ ]])
+ ],
+ [sched_set_affinity_args=3],
+ [sched_set_affinity_args=2])
+ AC_DEFINE_UNQUOTED(SCHED_SETAFFINITY_ARGS,
+ $sched_set_affinity_args,
+ [Defined to sched_setaffinity's number of arguments.])
+ AC_MSG_RESULT([$sched_set_affinity_args])
+ ],[
+ # No cpu_set_t, always 3 args.
+ AC_DEFINE(SCHED_SETAFFINITY_ARGS, 3)
+ ])
+])
+
+
+## ##
+## Set automake variables for optional feature conditionnals in Makefile.am ##
+## ##
+
+# Building the examples requires the shared libraries to be enabled
+AM_CONDITIONAL([ENABLE_EXAMPLES], AE_IS_FEATURE_ENABLED([shared]))
+
+
+## ##
+## Substitute variables for use in Makefile.am ##
+## ##
+
+# Library versions for libtool
+AC_SUBST([URCU_LIBRARY_VERSION], [urcu_lib_version])
+
+AC_SUBST(LT_NO_UNDEFINED)
+
+AM_CPPFLAGS="-include config.h"
+AC_SUBST(AM_CPPFLAGS)
+
+AM_CFLAGS="-Wall -Wextra -Wno-unused-parameter $PTHREAD_CFLAGS"
+AC_SUBST(AM_CFLAGS)