doc: Mention reason for replacement on glibc/Linux systems. * doc/posix-functions/dprintf.texi: Mention the problem with special 'long double' values. * doc/posix-functions/fprintf.texi: Likewise. * doc/posix-functions/printf.texi: Likewise. * doc/posix-functions/snprintf.texi: Likewise. * doc/posix-functions/sprintf.texi: Likewise. * doc/posix-functions/vdprintf.texi: Likewise. * doc/posix-functions/vfprintf.texi: Likewise. * doc/posix-functions/vprintf.texi: Likewise. * doc/posix-functions/vsnprintf.texi: Likewise. * doc/posix-functions/vsprintf.texi: Likewise. * doc/posix-functions/fcntl.texi: Add glibc/Linux to the list of platforms with F_DUPFD_CLOEXEC problems. * doc/posix-functions/glob.texi: Mention which platforms are affected by the problem with symbolic links. * doc/posix-functions/linkat.texi: Mention the problem with AT_SYMLINK_FOLLOW on Linux.

--- a/doc/posix-functions/vfprintf.texi
+++ b/doc/posix-functions/vfprintf.texi
@@ -20,6 +20,10 @@
 incorrect result on some platforms:
 AIX 5.2, OSF/1 5.1, Solaris 11 2011-11, mingw, MSVC 9.
 @item
+printf of @samp{long double} numbers outside the IEEE 754 range produces
+no meaningful results on some platforms:
+glibc and others, on x86, x86_64, IA-64 CPUs.
+@item
 This function does not support the @samp{a} and @samp{A} directives on some
 platforms:
 glibc-2.3.6, MacOS X 10.5, NetBSD 5.0, OpenBSD 4.0, AIX 5.2, HP-UX 11,