From 9674ece7b2e57e265bd1dc55a623cc7888a1caa0 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Tue, 18 Sep 2018 15:46:31 +0200
Subject: Elaborate the disclaimer for 'pktoptions'

---
 lib/kernel/doc/src/gen_tcp.xml | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'lib')

diff --git a/lib/kernel/doc/src/gen_tcp.xml b/lib/kernel/doc/src/gen_tcp.xml
index cf649991d0..24d63693fd 100644
--- a/lib/kernel/doc/src/gen_tcp.xml
+++ b/lib/kernel/doc/src/gen_tcp.xml
@@ -74,13 +74,25 @@ do_recv(Sock, Bs) ->
       <desc>
 	<p>
 	  If the platform implements the IPv4 option
-	  <c>IP_PKTOPTIONS</c> (probably Linux specific), or the IPv6 option
+	  <c>IP_PKTOPTIONS</c>, or the IPv6 option
 	  <c>IPV6_PKTOPTIONS</c> or <c>IPV6_2292PKTOPTIONS</c> for the socket
 	  this value is returned from
 	  <seealso marker="inet#getopts/2"><c>inet:getopts/2</c></seealso>
 	  when called with the option name
 	  <seealso marker="#type-option_name"><c>pktoptions</c></seealso>.
 	</p>
+	<note>
+	  <p>
+	    This option appears to be VERY Linux specific,
+	    and its existence in future Linux kernel versions
+	    is also worrying since the option is part of RFC 2292
+	    which is since long (2003) obsoleted by RFC 3542
+	    that <em>explicitly</em> removes this possibility to get
+	    packet information from a stream socket.
+	    For comparision: it has existed in FreeBSD but is now removed,
+	    at least since FreeBSD 10.
+	  </p>
+	</note>
       </desc>
     </datatype>
     <datatype>
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