Add message suggesting gdbserver for non-matching PID namespaces.

gdb-upstream.patch

@@ -153,3 +153,63 @@ index 1eb457d..ce60beb 100644
 -- 
 2.5.0
 
+
+
+http://sourceware.org/ml/gdb-patches/2016-03/msg00246.html
+Subject: [patch] Suggest running gdbserver for a PID in container
+
+
+--azLHFNyN32YCQGCU
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline
+
+Hi,
+
+currently
+	gdb -p <pid from a container>
+will print:
+	warning: Target and debugger are in different PID namespaces; thread lists and other data are likely unreliable
+
+BTW it is a bit lost in all the other messages.  Full screen output is in:
+	https://sourceware.org/bugzilla/show_bug.cgi?id=19828
+
+It correctly states the problem but it does not say how to solve it.
+
+Is at least this little suggestion OK?
+
+Originally I wanted to suggest also the Docker "-p 1234:1234" parameter but
+I see the containers are more general topic than just Docker (even LxC etc.).
+
+According to Gary future GDBs should be able to work even without gdbserver.
+But currently gdbserver is still required.
+
+
+Thanks,
+Jan
+
+--azLHFNyN32YCQGCU
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline; filename=1
+
+gdb/ChangeLog
+2016-03-15  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* linux-thread-db.c (check_pid_namespace_match): Extend the message.
+
+diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
+index 1eb457d..21166bf 100644
+--- a/gdb/linux-thread-db.c
++++ b/gdb/linux-thread-db.c
+@@ -1020,7 +1020,8 @@ check_pid_namespace_match (void)
+ 	{
+ 	  warning (_ ("Target and debugger are in different PID "
+ 		      "namespaces; thread lists and other data are "
+-		      "likely unreliable"));
++		      "likely unreliable.  "
++		      "Connect to gdbserver inside the container."));
+ 	}
+     }
+ }
+
+--azLHFNyN32YCQGCU--
+

gdb.spec

@@ -27,7 +27,7 @@ Version: 7.11
 
 # The release always contains a leading reserved number, start it at 1.
 # `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing.
-Release: 60%{?dist}
+Release: 61%{?dist}
 
 License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and BSD and Public Domain and GFDL
 Group: Development/Debuggers
@@ -1393,6 +1393,9 @@ then
 fi
 
 %changelog
+* Thu Mar 17 2016 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.11-61.fc24
+- Add message suggesting gdbserver for non-matching PID namespaces.
+
 * Tue Mar 15 2016 Jan Kratochvil <jan.kratochvil@redhat.com> - 7.11-60.fc24
 - New Fedora GDB testfile: rhbz1261564-aarch64-watchpoint.exp
 - Backport gdb-7.11 stable branch PR gdb/19676 fix (Pedro Alves).