diff --git a/.gitignore b/.gitignore
index f40064d..789f57e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,20 @@
+# Random seed file created by test scripts and sample programs
+seedfile
+
+# CMake build artifacts:
 CMakeCache.txt
 CMakeFiles
 CTestTestfile.cmake
 cmake_install.cmake
 Testing
+# CMake generates *.dir/ folders for in-tree builds (used by MSVC projects), ignore all of those:
+*.dir/
+# MSVC files generated by CMake:
+/*.sln
+/*.vcxproj
+/*.filters
+
+# Test coverage build artifacts:
 Coverage
 *.gcno
 *.gcda
@@ -10,11 +22,6 @@
 # generated by scripts/memory.sh
 massif-*
 
-# MSVC files generated by CMake:
-/*.sln
-/*.vcxproj
-/*.filters
-
 # MSVC build artifacts:
 *.exe
 *.pdb
@@ -24,5 +31,13 @@
 # Python build artifacts:
 *.pyc
 
-# CMake generates *.dir/ folders for in-tree builds (used by MSVC projects), ignore all of those:
-*.dir/
+# Generated documentation:
+/apidoc
+
+# Editor navigation files:
+/GPATH
+/GRTAGS
+/GSYMS
+/GTAGS
+/TAGS
+/tags
diff --git a/.globalrc b/.globalrc
new file mode 100644
index 0000000..01b2ea5
--- /dev/null
+++ b/.globalrc
@@ -0,0 +1,3 @@
+default:\
+    :langmap=c\:.c.h.function:\
+
diff --git a/ChangeLog b/ChangeLog
index 5bda25c..1196de5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,14 @@
 
 = mbed TLS 2.x.x branch released xxxx-xx-xx
 
+Security
+   * Make mbedtls_ecdh_get_params return an error if the second key
+     belongs to a different group from the first. Before, if an application
+     passed keys that belonged to different group, the first key's data was
+     interpreted according to the second group, which could lead to either
+     an error or a meaningless output from mbedtls_ecdh_get_params. In the
+     latter case, this could expose at most 5 bits of the private key.
+
 Features
    * Add support for draft-05 of the Connection ID extension, as specified
      in https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05.
@@ -13,14 +21,6 @@
      MBEDTLS_SSL_DTLS_CONNECTION_ID (disabled by default), and at run-time
      through the new APIs mbedtls_ssl_conf_cid() and mbedtls_ssl_set_cid().
 
-Security
-   * Make mbedtls_ecdh_get_params return an error if the second key
-     belongs to a different group from the first. Before, if an application
-     passed keys that belonged to different group, the first key's data was
-     interpreted according to the second group, which could lead to either
-     an error or a meaningless output from mbedtls_ecdh_get_params. In the
-     latter case, this could expose at most 5 bits of the private key.
-
 Bugfix
    * Server's RSA certificate in certs.c was SHA-1 signed. In the default
      mbedTLS configuration only SHA-2 signed certificates are accepted.
@@ -57,6 +57,8 @@
      Found by Coverity, reported and fixed by Peter Kolbus (Garmin). Fixes #2309.
    * Add test for minimal value of MBEDTLS_MPI_WINDOW_SIZE to all.sh.
      Contributed by Peter Kolbus (Garmin).
+   * Change wording in the `mbedtls_ssl_conf_max_frag_len()`'s documentation to
+     improve clarity. Fixes #2258.
 
 = mbed TLS 2.16.1 branch released 2019-03-19
 
diff --git a/Makefile b/Makefile
index f4c0a00..1ae6bd9 100644
--- a/Makefile
+++ b/Makefile
@@ -120,3 +120,12 @@
 apidoc_clean:
 	rm -rf apidoc
 endif
+
+## Editor navigation files
+C_SOURCE_FILES = $(wildcard include/*/*.h library/*.[hc] programs/*/*.[hc] tests/suites/*.function)
+tags: $(C_SOURCE_FILES)
+	ctags -o $@ $(C_SOURCE_FILES)
+TAGS: $(C_SOURCE_FILES)
+	etags -o $@ $(C_SOURCE_FILES)
+GPATH GRTAGS GSYMS GTAGS: $(C_SOURCE_FILES)
+	ls $(C_SOURCE_FILES) | gtags -f - --gtagsconf .globalrc
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 7127710..7571a3f 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -2764,22 +2764,28 @@
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
 /**
- * \brief          Set the maximum fragment length to emit and/or negotiate
- *                 (Default: the smaller of MBEDTLS_SSL_IN_CONTENT_LEN and
- *                 MBEDTLS_SSL_OUT_CONTENT_LEN, usually 2^14 bytes)
+ * \brief          Set the maximum fragment length to emit and/or negotiate.
+ *                 (Typical: the smaller of #MBEDTLS_SSL_IN_CONTENT_LEN and
+ *                 #MBEDTLS_SSL_OUT_CONTENT_LEN, usually `2^14` bytes)
  *                 (Server: set maximum fragment length to emit,
- *                 usually negotiated by the client during handshake
+ *                 usually negotiated by the client during handshake)
  *                 (Client: set maximum fragment length to emit *and*
  *                 negotiate with the server during handshake)
+ *                 (Default: #MBEDTLS_SSL_MAX_FRAG_LEN_NONE)
  *
- * \note           With TLS, this currently only affects ApplicationData (sent
- *                 with \c mbedtls_ssl_read()), not handshake messages.
- *                 With DTLS, this affects both ApplicationData and handshake.
+ * \note           On the client side, the maximum fragment length extension
+ *                 *will not* be used, unless the maximum fragment length has
+ *                 been set via this function to a value different than
+ *                 #MBEDTLS_SSL_MAX_FRAG_LEN_NONE.
  *
  * \note           This sets the maximum length for a record's payload,
  *                 excluding record overhead that will be added to it, see
  *                 \c mbedtls_ssl_get_record_expansion().
  *
+ * \note           With TLS, this currently only affects ApplicationData (sent
+ *                 with \c mbedtls_ssl_read()), not handshake messages.
+ *                 With DTLS, this affects both ApplicationData and handshake.
+ *
  * \note           For DTLS, it is also possible to set a limit for the total
  *                 size of daragrams passed to the transport layer, including
  *                 record overhead, see \c mbedtls_ssl_set_mtu().
diff --git a/scripts/abi_check.py b/scripts/abi_check.py
index f837f7a..30c3fe5 100755
--- a/scripts/abi_check.py
+++ b/scripts/abi_check.py
@@ -148,7 +148,8 @@
         my_environment = os.environ.copy()
         my_environment["CFLAGS"] = "-g -Og"
         my_environment["SHARED"] = "1"
-        my_environment["USE_CRYPTO_SUBMODULE"] = "1"
+        if os.path.exists(os.path.join(git_worktree_path, "crypto")):
+            my_environment["USE_CRYPTO_SUBMODULE"] = "1"
         make_output = subprocess.check_output(
             [self.make_command, "lib"],
             env=my_environment,
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 72e7c3e..5150cd6 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -576,7 +576,7 @@
 
 component_check_names () {
     msg "test/build: declared and exported names" # < 3s
-    record_status tests/scripts/check-names.sh
+    record_status tests/scripts/check-names.sh -v
 }
 
 component_check_doxygen_warnings () {
diff --git a/tests/scripts/check-names.sh b/tests/scripts/check-names.sh
index 6d9ab0e..ecfe277 100755
--- a/tests/scripts/check-names.sh
+++ b/tests/scripts/check-names.sh
@@ -2,26 +2,42 @@
 #
 # This file is part of mbed TLS (https://tls.mbed.org)
 #
-# Copyright (c) 2015-2016, ARM Limited, All Rights Reserved
-#
-# Purpose
-#
-# This script confirms that the naming of all symbols and identifiers in mbed
-# TLS are consistent with the house style and are also self-consistent.
-#
+# Copyright (c) 2015-2019, ARM Limited, All Rights Reserved
+
 set -eu
 
+if [ $# -ne 0 ] && [ "$1" = "--help" ]; then
+    cat <<EOF
+$0 [-v]
+This script confirms that the naming of all symbols and identifiers in mbed
+TLS are consistent with the house style and are also self-consistent.
+
+  -v    If the script fails unexpectedly, print a command trace.
+EOF
+    exit
+fi
+
 if grep --version|head -n1|grep GNU >/dev/null; then :; else
     echo "This script requires GNU grep.">&2
     exit 1
 fi
 
+trace=
+if [ $# -ne 0 ] && [ "$1" = "-v" ]; then
+  shift
+  trace='-x'
+  exec 2>check-names.err
+  trap 'echo "FAILED UNEXPECTEDLY, status=$?";
+        cat check-names.err' EXIT
+  set -x
+fi
+
 printf "Analysing source code...\n"
 
-tests/scripts/list-macros.sh
+sh $trace tests/scripts/list-macros.sh
 tests/scripts/list-enum-consts.pl
-tests/scripts/list-identifiers.sh
-tests/scripts/list-symbols.sh
+sh $trace tests/scripts/list-identifiers.sh
+sh $trace tests/scripts/list-symbols.sh
 
 FAIL=0
 
@@ -89,6 +105,12 @@
     FAIL=1
 fi
 
+if [ -n "$trace" ]; then
+  set +x
+  trap - EXIT
+  rm check-names.err
+fi
+
 printf "\nOverall: "
 if [ "$FAIL" -eq 0 ]; then
     rm macros actual-macros enum-consts identifiers exported-symbols undeclared
diff --git a/tests/scripts/list-symbols.sh b/tests/scripts/list-symbols.sh
index c258719..930722c 100755
--- a/tests/scripts/list-symbols.sh
+++ b/tests/scripts/list-symbols.sh
@@ -14,8 +14,21 @@
 
 cp include/mbedtls/config.h include/mbedtls/config.h.bak
 scripts/config.pl full
-CFLAGS=-fno-asynchronous-unwind-tables make clean lib >/dev/null 2>&1
+make clean
+make_ret=
+CFLAGS=-fno-asynchronous-unwind-tables make lib \
+      >list-symbols.make.log 2>&1 ||
+  {
+    make_ret=$?
+    echo "Build failure: CFLAGS=-fno-asynchronous-unwind-tables make lib"
+    cat list-symbols.make.log >&2
+  }
+rm list-symbols.make.log
 mv include/mbedtls/config.h.bak include/mbedtls/config.h
+if [ -n "$make_ret" ]; then
+    exit "$make_ret"
+fi
+
 if uname | grep -F Darwin >/dev/null; then
     nm -gUj library/libmbed*.a 2>/dev/null | sed -n -e 's/^_//p'
 elif uname | grep -F Linux >/dev/null; then