+# 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);
+# ~~~~
+
+dnl Since we define _GNU_SOURCE in the sources, must do so too in the
+dnl autoconf tests, as defining _GNU_SOURCE or not exposes
+dnl sched_setaffinity bits differently.
+saved_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -D_GNU_SOURCE"
+
+# 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.
+
+ AC_CHECK_TYPES(
+ [cpu_set_t],
+ [ # We do have it. Confirm that we have CPU_ZERO, and it actually works.
+ AC_MSG_CHECKING([whether CPU_ZERO works])
+ AH_TEMPLATE([HAVE_CPU_ZERO],
+ [Define to 1 if we have CPU_ZERO and if it works])
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#define _GNU_SOURCE
+ #include <sched.h>],
+ [cpu_set_t foo; CPU_ZERO (&foo);])
+ ],
+ [ # Works!
+ AC_DEFINE(HAVE_CPU_ZERO, 1)
+ AC_MSG_RESULT([yes])
+ ],
+ [AC_MSG_RESULT([no])]
+ )
+
+ # 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_PROGRAM(
+ [#include <sched.h>],
+ [cpu_set_t foo; sched_setaffinity (0, sizeof (foo), &foo);])
+ ],
+ [sched_set_affinity_args=3],
+ [sched_set_affinity_args=2])
+ AC_DEFINE_UNQUOTED(SCHED_SETAFFINITY_ARGS, $sched_set_affinity_args,
+ [Define to sched_setaffinity's number of arguments.])
+ AC_MSG_RESULT([$sched_set_affinity_args])
+ ],
+ [ # No cpu_set_t, always 3 args.
+ AC_DEFINE(SCHED_SETAFFINITY_ARGS, 3) ],
+ [#include <sched.h>]
+ )
+ ]
+)
+
+CFLAGS=$saved_CFLAGS
+
+AC_CONFIG_LINKS([
+ urcu/arch.h:$ARCHSRC
+ urcu/uatomic.h:$UATOMICSRC
+ tests/api.h:$APISRC
+])