doc: Mark functions which exist only on Linux.

35 files changed, 71 insertions, 36 deletions

diff --git a/doc/glibc-functions/adjtimex.texi b/doc/glibc-functions/adjtimex.texi
index 3ce67af3c0..d81f7f34fb 100644
--- a/doc/glibc-functions/adjtimex.texi
+++ b/doc/glibc-functions/adjtimex.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 6.0.
 @end itemize
diff --git a/doc/glibc-functions/bdflush.texi b/doc/glibc-functions/bdflush.texi
index 2c1cfbf3c6..a892934598 100644
--- a/doc/glibc-functions/bdflush.texi
+++ b/doc/glibc-functions/bdflush.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/capget.texi b/doc/glibc-functions/capget.texi
index 08ae5d8308..6a13bb3054 100644
--- a/doc/glibc-functions/capget.texi
+++ b/doc/glibc-functions/capget.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS.
 @end itemize
diff --git a/doc/glibc-functions/capset.texi b/doc/glibc-functions/capset.texi
index 2cf2259a1f..b6f014d6a0 100644
--- a/doc/glibc-functions/capset.texi
+++ b/doc/glibc-functions/capset.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS.
 @end itemize
diff --git a/doc/glibc-functions/clock_adjtime.texi b/doc/glibc-functions/clock_adjtime.texi
index f7822d9795..728e1d89e3 100644
--- a/doc/glibc-functions/clock_adjtime.texi
+++ b/doc/glibc-functions/clock_adjtime.texi
@@ -11,6 +11,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.13, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 6.0.
 @end itemize
diff --git a/doc/glibc-functions/copy_file_range.texi b/doc/glibc-functions/copy_file_range.texi
index b257ff88f7..2e6d25100f 100644
--- a/doc/glibc-functions/copy_file_range.texi
+++ b/doc/glibc-functions/copy_file_range.texi
@@ -20,7 +20,8 @@ Gnulib module: copy-file-range
 Portability problems fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 But the replacement function is only a stub: It always fails with error ENOSYS.
 @end itemize
diff --git a/doc/glibc-functions/fallocate.texi b/doc/glibc-functions/fallocate.texi
index 8af648e436..c7ecf896d9 100644
--- a/doc/glibc-functions/fallocate.texi
+++ b/doc/glibc-functions/fallocate.texi
@@ -13,7 +13,8 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on older glibc versions and many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on older glibc versions and many non-glibc platforms:
 glibc 2.9, 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.4.
 @item
 On platforms where @code{off_t} is a 32-bit type, this function may not
diff --git a/doc/glibc-functions/fanotify_init.texi b/doc/glibc-functions/fanotify_init.texi
index a434ace2b7..1deb906beb 100644
--- a/doc/glibc-functions/fanotify_init.texi
+++ b/doc/glibc-functions/fanotify_init.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.12, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/fanotify_mark.texi b/doc/glibc-functions/fanotify_mark.texi
index 0eeb63c78f..efa5db526e 100644
--- a/doc/glibc-functions/fanotify_mark.texi
+++ b/doc/glibc-functions/fanotify_mark.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.12, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/getcpu.texi b/doc/glibc-functions/getcpu.texi
index 091304d285..78e54d70f5 100644
--- a/doc/glibc-functions/getcpu.texi
+++ b/doc/glibc-functions/getcpu.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.28, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/getfilecon-desc.texi b/doc/glibc-functions/getfilecon-desc.texi
index f0166ff76e..a9d2b1d09b 100644
--- a/doc/glibc-functions/getfilecon-desc.texi
+++ b/doc/glibc-functions/getfilecon-desc.texi
@@ -4,8 +4,9 @@ Gnulib module: selinux-h
 Portability problems fixed by Gnulib:
 @itemize
 @item
-This function is missing on some platforms:
-Mac OS X 10.5, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11.4, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
+Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 On those platforms, this module provides a stub that always sets
 @code{errno} to @code{ENOTSUP} and returns @samp{-1}.
 @item
diff --git a/doc/glibc-functions/klogctl.texi b/doc/glibc-functions/klogctl.texi
index 6018923a08..4304391f61 100644
--- a/doc/glibc-functions/klogctl.texi
+++ b/doc/glibc-functions/klogctl.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS.
 @end itemize
diff --git a/doc/glibc-functions/memfd_create.texi b/doc/glibc-functions/memfd_create.texi
index f69413a750..3c0c9527f0 100644
--- a/doc/glibc-functions/memfd_create.texi
+++ b/doc/glibc-functions/memfd_create.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/mlock2.texi b/doc/glibc-functions/mlock2.texi
index 5a08235c5d..b7efb6bf6d 100644
--- a/doc/glibc-functions/mlock2.texi
+++ b/doc/glibc-functions/mlock2.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/name_to_handle_at.texi b/doc/glibc-functions/name_to_handle_at.texi
index c38504da6e..0b66707a2d 100644
--- a/doc/glibc-functions/name_to_handle_at.texi
+++ b/doc/glibc-functions/name_to_handle_at.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.13, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/open_by_handle_at.texi b/doc/glibc-functions/open_by_handle_at.texi
index dd2c1a3437..d31aa2a9c5 100644
--- a/doc/glibc-functions/open_by_handle_at.texi
+++ b/doc/glibc-functions/open_by_handle_at.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.13, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/personality.texi b/doc/glibc-functions/personality.texi
index 14d3cbb625..2245789ba1 100644
--- a/doc/glibc-functions/personality.texi
+++ b/doc/glibc-functions/personality.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.0.2.
 @end itemize
diff --git a/doc/glibc-functions/pkey_alloc.texi b/doc/glibc-functions/pkey_alloc.texi
index f6c454f0b3..872d1987db 100644
--- a/doc/glibc-functions/pkey_alloc.texi
+++ b/doc/glibc-functions/pkey_alloc.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/pkey_free.texi b/doc/glibc-functions/pkey_free.texi
index e5bb228f7d..5d84f1ce9a 100644
--- a/doc/glibc-functions/pkey_free.texi
+++ b/doc/glibc-functions/pkey_free.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/pkey_get.texi b/doc/glibc-functions/pkey_get.texi
index 93b50b5ea2..30a9e8995f 100644
--- a/doc/glibc-functions/pkey_get.texi
+++ b/doc/glibc-functions/pkey_get.texi
@@ -19,6 +19,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/pkey_mprotect.texi b/doc/glibc-functions/pkey_mprotect.texi
index 62d44fad0b..5235febfc2 100644
--- a/doc/glibc-functions/pkey_mprotect.texi
+++ b/doc/glibc-functions/pkey_mprotect.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/pkey_set.texi b/doc/glibc-functions/pkey_set.texi
index e140d38ed3..469a2a7c8e 100644
--- a/doc/glibc-functions/pkey_set.texi
+++ b/doc/glibc-functions/pkey_set.texi
@@ -19,6 +19,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.26, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/preadv2.texi b/doc/glibc-functions/preadv2.texi
index 0974d4e572..880237c6fb 100644
--- a/doc/glibc-functions/preadv2.texi
+++ b/doc/glibc-functions/preadv2.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.25, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/prlimit.texi b/doc/glibc-functions/prlimit.texi
index 0517d0d059..aa629ec65b 100644
--- a/doc/glibc-functions/prlimit.texi
+++ b/doc/glibc-functions/prlimit.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.12, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 6.0.
 @end itemize
diff --git a/doc/glibc-functions/process_vm_readv.texi b/doc/glibc-functions/process_vm_readv.texi
index 7d87d8da92..8dc4a4890e 100644
--- a/doc/glibc-functions/process_vm_readv.texi
+++ b/doc/glibc-functions/process_vm_readv.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.14, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 5.1.
 @end itemize
diff --git a/doc/glibc-functions/process_vm_writev.texi b/doc/glibc-functions/process_vm_writev.texi
index 7925ac9aec..fe60e8303c 100644
--- a/doc/glibc-functions/process_vm_writev.texi
+++ b/doc/glibc-functions/process_vm_writev.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.14, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 5.1.
 @end itemize
diff --git a/doc/glibc-functions/pwritev2.texi b/doc/glibc-functions/pwritev2.texi
index 54bfc2182a..d450b54bb4 100644
--- a/doc/glibc-functions/pwritev2.texi
+++ b/doc/glibc-functions/pwritev2.texi
@@ -24,6 +24,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.25, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/readahead.texi b/doc/glibc-functions/readahead.texi
index 89c982dd81..bcffff600b 100644
--- a/doc/glibc-functions/readahead.texi
+++ b/doc/glibc-functions/readahead.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.0.4.
 @end itemize
diff --git a/doc/glibc-functions/remap_file_pages.texi b/doc/glibc-functions/remap_file_pages.texi
index 4de29698b7..6e1acef33a 100644
--- a/doc/glibc-functions/remap_file_pages.texi
+++ b/doc/glibc-functions/remap_file_pages.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/renameat2.texi b/doc/glibc-functions/renameat2.texi
index 90f1fc198d..dcb4f03e0b 100644
--- a/doc/glibc-functions/renameat2.texi
+++ b/doc/glibc-functions/renameat2.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on all non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on all non-glibc platforms:
 glibc 2.27, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 9.0.
 @end itemize
diff --git a/doc/glibc-functions/sched_getcpu.texi b/doc/glibc-functions/sched_getcpu.texi
index 0ae20c3020..f60ab5021b 100644
--- a/doc/glibc-functions/sched_getcpu.texi
+++ b/doc/glibc-functions/sched_getcpu.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on most non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on most non-glibc platforms:
 glibc 2.5, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS.
 @end itemize
diff --git a/doc/glibc-functions/setfsgid.texi b/doc/glibc-functions/setfsgid.texi
index 7a82324e90..176d285f0d 100644
--- a/doc/glibc-functions/setfsgid.texi
+++ b/doc/glibc-functions/setfsgid.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.4.
 @end itemize
diff --git a/doc/glibc-functions/setfsuid.texi b/doc/glibc-functions/setfsuid.texi
index cb29f5e192..ed4817f56d 100644
--- a/doc/glibc-functions/setfsuid.texi
+++ b/doc/glibc-functions/setfsuid.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 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 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.4.
 @end itemize
diff --git a/doc/glibc-functions/setns.texi b/doc/glibc-functions/setns.texi
index e011cfe5af..8e925c2953 100644
--- a/doc/glibc-functions/setns.texi
+++ b/doc/glibc-functions/setns.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.13, Mac OS X 10.5, FreeBSD 6.4, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.4.
 @end itemize
diff --git a/doc/glibc-functions/sync_file_range.texi b/doc/glibc-functions/sync_file_range.texi
index 2b458c4db9..f23530cbb5 100644
--- a/doc/glibc-functions/sync_file_range.texi
+++ b/doc/glibc-functions/sync_file_range.texi
@@ -13,6 +13,7 @@ Portability problems fixed by Gnulib:
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on many non-glibc platforms:
+This function exists only on Linux and is therefore
+missing on many non-glibc platforms:
 glibc 2.5, Mac OS X 10.5, FreeBSD 12.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, OSF/1 5.1, Solaris 11.4, Cygwin, mingw, MSVC 14, Interix 3.5, BeOS, Android 4.3.
 @end itemize