-# 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])
+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.])