@itemize
@item
This function is missing on many non-glibc platforms:
-MacOS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, AIX 5.1, HP-UX 11,
-IRIX 6.5, OSF/1 5.1, Solaris 10, Cygwin 1.7.1, mingw, Interix 3.5, BeOS.
+Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11,
+IRIX 6.5, OSF/1 5.1, Solaris 11 2011-11, Cygwin 1.7.1, mingw, MSVC 9, Interix 3.5, BeOS.
+But the replacement function is not atomic; this matters in multi-threaded
+programs that spawn child processes.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
+@item
+This function crashes rather than failing with @code{EMFILE} if no
+resources are left on some platforms:
+Cygwin 1.7.9.
@end itemize
+
+Note: This function portably supports the @code{O_NONBLOCK} flag only if the
+gnulib module @code{nonblocking} is also used.