+#
+# Check for xxxat() functions when we are building linux-user
+# emulator. This is done because older glibc versions don't
+# have syscall stubs for these implemented.
+#
+atfile=no
+if [ "$linux_user" = "yes" ] ; then
+ cat > $TMPC << EOF
+#define _ATFILE_SOURCE
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int
+main(void)
+{
+ /* try to unlink nonexisting file */
+ return (unlinkat(AT_FDCWD, "nonexistent_file", 0));
+}
+EOF
+ if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null > /dev/null ; then
+ atfile=yes
+ fi
+fi
+
+# Check for inotify functions when we are building linux-user
+# emulator. This is done because older glibc versions don't
+# have syscall stubs for these implemented. In that case we
+# don't provide them even if kernel supports them.
+#
+inotify=no
+if [ "$linux_user" = "yes" ] ; then
+ cat > $TMPC << EOF
+#include <sys/inotify.h>
+
+int
+main(void)
+{
+ /* try to start inotify */
+ return inotify_init();
+}
+EOF
+ if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null > /dev/null ; then
+ inotify=yes
+ fi
+fi
+
+# check if utimensat and futimens are supported
+utimens=no
+cat > $TMPC << EOF
+#define _ATFILE_SOURCE
+#define _GNU_SOURCE
+#include <stddef.h>
+#include <fcntl.h>
+
+int main(void)
+{
+ utimensat(AT_FDCWD, "foo", NULL, 0);
+ futimens(0, NULL);
+ return 0;
+}
+EOF
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+ utimens=yes
+fi
+
+# check if pipe2 is there
+pipe2=no
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+
+int main(void)
+{
+ int pipefd[2];
+ pipe2(pipefd, O_CLOEXEC);
+ return 0;
+}
+EOF
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+ pipe2=yes
+fi
+
+# check if tee/splice is there. vmsplice was added same time.
+splice=no
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+#include <limits.h>
+
+int main(void)
+{
+ int len, fd;
+ len = tee(STDIN_FILENO, STDOUT_FILENO, INT_MAX, SPLICE_F_NONBLOCK);
+ splice(STDIN_FILENO, NULL, fd, NULL, len, SPLICE_F_MOVE);
+ return 0;
+}
+EOF
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+ splice=yes
+fi
+