diff --git a/.travis.yml b/.travis.yml
index b15bc89e5..0ce5d9c42 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,9 +13,12 @@ addons:
 script:
   - set -e
   - export CXX="g++-4.8" CC="gcc-4.8" GCOV="gcov-4.8"
+  - echo -e "travis_fold:start:host_tests"
   - pushd $TRAVIS_BUILD_DIR/tests/host
   - make
   - make clean-objects
+  - echo -e "travis_fold:end:host_tests"
+  - echo -e "travis_fold:start:sketch_test_env_prepare"
   - popd
   - wget -O arduino.tar.xz https://www.arduino.cc/download.php?f=/arduino-nightly-linux64.tar.xz
   - tar xf arduino.tar.xz
@@ -26,15 +29,18 @@ script:
   - ln -s $TRAVIS_BUILD_DIR esp8266
   - cd esp8266/tools
   - python get.py
-  - /sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_1.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :1 -ac -screen 0 1280x1024x16
-  - sleep 3
-  - export DISPLAY=:1.0
-  - export PATH="$HOME/arduino_ide:$PATH"
+  - export PATH="$HOME/arduino_ide:$TRAVIS_BUILD_DIR/tools/xtensa-lx106-elf/bin:$PATH"
   - which arduino
   - cd $TRAVIS_BUILD_DIR
   - source tests/common.sh
   - install_libraries
-  - build_sketches $HOME/arduino_ide $TRAVIS_BUILD_DIR "python tools/build.py -l $HOME/Arduino/libraries -b generic -v"
+  - echo -e "travis_fold:end:sketch_test_env_prepare"
+  - echo -e "travis_fold:start:sketch_test"
+  - build_sketches $HOME/arduino_ide $TRAVIS_BUILD_DIR "-l $HOME/Arduino/libraries"
+  - echo -e "travis_fold:end:sketch_test"
+  - echo -e "travis_fold:start:size_report"
+  - cat size.log
+  - echo -e "travis_fold:end:size_report"
 
 after_success:
     - pushd $TRAVIS_BUILD_DIR/tests/host
diff --git a/README.md b/README.md
index 1affadda4..cbb7da28a 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ ESP8266 Arduino core comes with libraries to communicate over WiFi using TCP and
 
 Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32 and 64 bit).
 
-- Install Arduino 1.6.5 from the [Arduino website](http://www.arduino.cc/en/main/software).
+- Install Arduino 1.6.8 from the [Arduino website](http://www.arduino.cc/en/main/software).
 - Start Arduino and open Preferences window.
 - Enter ```http://arduino.esp8266.com/stable/package_esp8266com_index.json``` into *Additional Board Manager URLs* field. You can add multiple URLs, separating them with commas.
 - Open Boards Manager from Tools > Board menu and install *esp8266* platform (and don't forget to select your ESP8266 board from Tools > Board menu after installation).
@@ -44,7 +44,7 @@ Documentation: [http://esp8266.github.io/Arduino/versions/2.1.0-rc2/](http://esp
 ### Using git version
 [![Linux build status](https://travis-ci.org/esp8266/Arduino.svg)](https://travis-ci.org/esp8266/Arduino) [![codecov.io](https://codecov.io/github/esp8266/Arduino/coverage.svg?branch=master)](https://codecov.io/github/esp8266/Arduino?branch=master)
 
-- Install Arduino 1.6.7
+- Install Arduino 1.6.8
 - Go to Arduino directory
 - Clone this repository into hardware/esp8266com/esp8266 directory (or clone it elsewhere and create a symlink)
 ```bash
diff --git a/cores/esp8266/Esp.h b/cores/esp8266/Esp.h
index 405a94c8e..80b041196 100644
--- a/cores/esp8266/Esp.h
+++ b/cores/esp8266/Esp.h
@@ -55,7 +55,8 @@ enum RFMode {
     RF_DISABLED = 4 // disable RF after deep-sleep wake up, just like modem sleep, there will be the smallest current.
 };
 
-#define RF_MODE(mode) extern "C" int __get_rf_mode() { return mode; }
+#define RF_MODE(mode) int __get_rf_mode() { return mode; }
+#define RF_PRE_INIT() void __run_user_rf_pre_init()
 
 // compatibility definitions
 #define WakeMode RFMode
@@ -71,7 +72,7 @@ enum ADCMode {
     ADC_VDD = 255
 };
 
-#define ADC_MODE(mode) extern "C" int __get_adc_mode(void) { return (int) (mode); }
+#define ADC_MODE(mode) int __get_adc_mode(void) { return (int) (mode); }
 
 typedef enum {
      FM_QIO = 0x00,
diff --git a/cores/esp8266/Tone.cpp b/cores/esp8266/Tone.cpp
index 9d262e3bb..bcdd358a8 100644
--- a/cores/esp8266/Tone.cpp
+++ b/cores/esp8266/Tone.cpp
@@ -113,11 +113,15 @@ void noTone(uint8_t _pin) {
   digitalWrite(_pin, LOW);
 }
 
-void t1IntHandler() {
-  if (toggle_counts[T1INDEX] > 0){
+ICACHE_RAM_ATTR void t1IntHandler() {
+  if (toggle_counts[T1INDEX] != 0){
     // toggle the pin
     digitalWrite(tone_pins[T1INDEX], toggle_counts[T1INDEX] % 2);
     toggle_counts[T1INDEX]--;
+    // handle the case of indefinite duration
+    if (toggle_counts[T1INDEX] < -2){
+      toggle_counts[T1INDEX] = -1;
+    }
   }else{
     disableTimer(T1INDEX);
     digitalWrite(tone_pins[T1INDEX], LOW);
diff --git a/cores/esp8266/core_esp8266_phy.c b/cores/esp8266/core_esp8266_phy.c
index acdbabf54..6b9b094eb 100644
--- a/cores/esp8266/core_esp8266_phy.c
+++ b/cores/esp8266/core_esp8266_phy.c
@@ -242,6 +242,14 @@ static const uint8_t ICACHE_FLASH_ATTR phy_init_data[128] =
     [114] = 2
 };
 
+// These functions will be overriden from C++ code.
+// Unfortunately, we can't use extern "C" because Arduino preprocessor
+// doesn't generate forward declarations for extern "C" functions correctly,
+// so we use mangled names here.
+#define __get_adc_mode _Z14__get_adc_modev
+#define __get_rf_mode _Z13__get_rf_modev
+#define __run_user_rf_pre_init _Z22__run_user_rf_pre_initv
+
 extern int __real_register_chipv6_phy(uint8_t* init_data);
 extern int __wrap_register_chipv6_phy(uint8_t* init_data) {
     if (init_data != NULL) {
@@ -279,5 +287,6 @@ void user_rf_pre_init() {
     }
 
     system_set_os_print(0);
+    system_phy_set_rfoption(__get_rf_mode());
     __run_user_rf_pre_init();
 }
diff --git a/cores/esp8266/core_esp8266_wiring.c b/cores/esp8266/core_esp8266_wiring.c
index 0170b4bcf..3a8f0f293 100644
--- a/cores/esp8266/core_esp8266_wiring.c
+++ b/cores/esp8266/core_esp8266_wiring.c
@@ -59,17 +59,17 @@ void micros_overflow_tick(void* arg) {
     micros_at_last_overflow_tick = m;
 }
 
-unsigned long millis() {
+unsigned long ICACHE_RAM_ATTR millis() {
     uint32_t m = system_get_time();
     uint32_t c = micros_overflow_count + ((m < micros_at_last_overflow_tick) ? 1 : 0);
     return c * 4294967 + m / 1000;
 }
 
-unsigned long micros() {
+unsigned long ICACHE_RAM_ATTR micros() {
     return system_get_time();
 }
 
-void delayMicroseconds(unsigned int us) {
+void ICACHE_RAM_ATTR delayMicroseconds(unsigned int us) {
     os_delay_us(us);
 }
 
diff --git a/cores/esp8266/core_esp8266_wiring_analog.c b/cores/esp8266/core_esp8266_wiring_analog.c
index 74d5dd5d3..1ff1d264d 100644
--- a/cores/esp8266/core_esp8266_wiring_analog.c
+++ b/cores/esp8266/core_esp8266_wiring_analog.c
@@ -1,9 +1,9 @@
-/* 
+/*
   analog.c - analogRead implementation for esp8266
 
   Copyright (c) 2015 Hristo Gochkov. All rights reserved.
   This file is part of the esp8266 core for Arduino environment.
- 
+
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
@@ -17,8 +17,8 @@
   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-  
-  
+
+
   18/06/2015 analogRead bugfix by Testato
 */
 
@@ -26,11 +26,13 @@
 #include "pins_arduino.h"
 
 
-extern int __analogRead(uint8_t pin) {
-  if(pin == 17){
-    return system_adc_read();
-  }
-  return digitalRead(pin) * 1023;
+extern int __analogRead(uint8_t pin)
+{
+    // accept both A0 constant and ADC channel number
+    if(pin == 17 || pin == 0) {
+        return system_adc_read();
+    }
+    return digitalRead(pin) * 1023;
 }
 
 extern int analogRead(uint8_t pin) __attribute__ ((weak, alias("__analogRead")));
diff --git a/doc/installing.md b/doc/installing.md
index 16ba27a00..55b03fe32 100644
--- a/doc/installing.md
+++ b/doc/installing.md
@@ -7,7 +7,7 @@ title: Installation
 This is the suggested installation method for end users.
 
 ### Prerequisites
-- Arduino 1.6.5, get it from [Arduino website](https://www.arduino.cc/en/Main/OldSoftwareReleases#previous). Arduino 1.6.6 has several issues, so we recommend to stick with 1.6.5 for now.
+- Arduino 1.6.8, get it from [Arduino website](https://www.arduino.cc/en/Main/OldSoftwareReleases#previous).
 - Internet connection
 
 ### Instructions
@@ -27,7 +27,7 @@ This is the suggested installation method for contributors and library developer
 
 ### Prerequisites
 
-- Arduino 1.6.5 (or newer, if you know what you are doing)
+- Arduino 1.6.8 (or newer, if you know what you are doing)
 - git
 - python 2.7
 - terminal, console, or command prompt (depending on you OS)
diff --git a/tests/common.sh b/tests/common.sh
index 8f3f083b0..a3cc30f36 100755
--- a/tests/common.sh
+++ b/tests/common.sh
@@ -1,13 +1,49 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+function print_size_info()
+{
+    elf_file=$1
+
+    if [ -z "$elf_file" ]; then
+        printf "sketch                       data     rodata   bss      text     irom0.text   dram     flash\n"
+        return 0
+    fi
+
+    elf_name=$(basename $elf_file)
+    sketch_name="${elf_name%.*}"
+    # echo $sketch_name
+    declare -A segments
+    while read -a tokens; do
+        seg=${tokens[0]}
+        seg=${seg//./}
+        size=${tokens[1]}
+        addr=${tokens[2]}
+        if [ "$addr" -eq "$addr" -a "$addr" -ne "0" ] 2>/dev/null; then
+            segments[$seg]=$size
+        fi
+
+
+    done < <(xtensa-lx106-elf-size --format=sysv $elf_file)
+
+    total_ram=$((${segments[data]} + ${segments[rodata]} + ${segments[bss]}))
+    total_flash=$((${segments[data]} + ${segments[rodata]} + ${segments[text]} + ${segments[irom0text]}))
+
+    printf "%-28s %-8d %-8d %-8d %-8d %-8d     %-8d %-8d\n" $sketch_name ${segments[data]} ${segments[rodata]} ${segments[bss]} ${segments[text]} ${segments[irom0text]} $total_ram $total_flash
+    return 0
+}
 
 function build_sketches()
 {
     set +e
     local arduino=$1
     local srcpath=$2
-    local build_cmd=$3
-    echo $build_cmd
+    local build_arg=$3
+    local build_dir=build.tmp
+    mkdir -p $build_dir
+    rm -rf $build_dir/*
+    local build_cmd="python tools/build.py -b generic -v -k -p $PWD/$build_dir $build_arg "
     local sketches=$(find $srcpath -name *.ino)
+    print_size_info >size.log
     export ARDUINO_IDE_PATH=$arduino
     for sketch in $sketches; do
         local sketchdir=$(dirname $sketch)
@@ -33,6 +69,7 @@ function build_sketches()
             return $result
         fi
         rm build.log
+        print_size_info $build_dir/*.elf >>size.log
     done
     set -e
 }
diff --git a/tests/test_overrides/test_overrides.ino b/tests/test_overrides/test_overrides.ino
new file mode 100644
index 000000000..fe963492f
--- /dev/null
+++ b/tests/test_overrides/test_overrides.ino
@@ -0,0 +1,11 @@
+ADC_MODE(ADC_VCC);
+RF_MODE(RF_DISABLED);
+RF_PRE_INIT()
+{
+}
+
+void setup() {
+}
+
+void loop() {
+}