diff --git a/components/esp8266/source/startup.c b/components/esp8266/source/startup.c
index 36ceddb6..cf0c7d9d 100644
--- a/components/esp8266/source/startup.c
+++ b/components/esp8266/source/startup.c
@@ -39,6 +39,7 @@ extern int base_gpio_init(void);
 extern int watchdog_init(void);
 extern int wifi_timer_init(void);
 extern int wifi_nvs_init(void);
+extern esp_err_t esp_pthread_init(void);
 
 static void user_init_entry(void *param)
 {
@@ -67,6 +68,10 @@ static void user_init_entry(void *param)
     esp_task_wdt_init();
 #endif
 
+#ifdef CONFIG_ENABLE_PTHREAD
+    assert(esp_pthread_init() == 0);
+#endif
+
     app_main();
 
     wifi_task_delete(NULL);
diff --git a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
index 2d728385..78d22eeb 100644
--- a/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
+++ b/components/freertos/port/esp8266/include/freertos/FreeRTOSConfig.h
@@ -152,7 +152,11 @@ NVIC value of 255. */
 #define configUSE_NEWLIB_REENTRANT  1
 #endif
 
+#ifdef CONFIG_ENABLE_PTHREAD
+#define configNUM_THREAD_LOCAL_STORAGE_POINTERS 2
+#else
 #define configNUM_THREAD_LOCAL_STORAGE_POINTERS 1
+#endif
 #define configTHREAD_LOCAL_STORAGE_DELETE_CALLBACKS 1
 
 /* add this to dump task stack information */
diff --git a/components/newlib/Makefile.projbuild b/components/newlib/Makefile.projbuild
index 733676d0..90b99fcb 100644
--- a/components/newlib/Makefile.projbuild
+++ b/components/newlib/Makefile.projbuild
@@ -1 +1,4 @@
-CFLAGS += -D_CLOCKS_PER_SEC_=CONFIG_FREERTOS_HZ
+CFLAGS += -D_CLOCKS_PER_SEC_=CONFIG_FREERTOS_HZ -D_POSIX_THREADS=1 -D_UNIX98_THREAD_MUTEX_ATTRIBUTES=1
+ifdef CONFIG_ENABLE_PTHREAD
+CFLAGS += -D_POSIX_THREADS=1 -D_UNIX98_THREAD_MUTEX_AT
+endif
diff --git a/components/newlib/newlib/include/sys/time.h b/components/newlib/newlib/include/sys/time.h
index be16497f..8e3ef808 100644
--- a/components/newlib/newlib/include/sys/time.h
+++ b/components/newlib/newlib/include/sys/time.h
@@ -20,7 +20,7 @@ struct timeval {
 };
 
 /* BSD time macros used by RTEMS code */
-#if defined (__rtems__) || defined (__CYGWIN__)
+#if defined (__rtems__) || defined (__CYGWIN__) || defined(__XTENSA__)
 
 /* Convenience macros for operations on timevals.
    NOTE: `timercmp' does not work for >= or <=.  */
diff --git a/components/newlib/newlib/port/syscall.c b/components/newlib/newlib/port/syscall.c
index f289b1df..a7fe205d 100644
--- a/components/newlib/newlib/port/syscall.c
+++ b/components/newlib/newlib/port/syscall.c
@@ -32,7 +32,7 @@ _ssize_t _read_r(struct _reent *r, int fd, void *buf, size_t len)
     return 0;
 }
 
-_ssize_t _write_r(struct _reent *r, int fd, void *buf, size_t len)
+_ssize_t _write_r(struct _reent *r, int fd, const void *buf, size_t len)
 {
     int i;
     const char *cbuf = buf;
diff --git a/components/pthread/Kconfig b/components/pthread/Kconfig
index 3f16c6ff..6c6d8fa1 100644
--- a/components/pthread/Kconfig
+++ b/components/pthread/Kconfig
@@ -1,5 +1,11 @@
 menu "PThreads"
 
+config ENABLE_PTHREAD
+    bool "Enable pthread"
+    default n
+    help
+        Enable this option and then pthread is to be used.
+
 config ESP32_PTHREAD_TASK_PRIO_DEFAULT
     int "Default task priority"
     range 0 255
diff --git a/components/pthread/component.mk b/components/pthread/component.mk
index 0dd23948..7528b1da 100644
--- a/components/pthread/component.mk
+++ b/components/pthread/component.mk
@@ -2,7 +2,9 @@
 # Component Makefile
 #
 
-COMPONENT_SRCDIRS := .
+ifdef CONFIG_ENABLE_PTHREAD
+COMPONENT_SRCDIRS := src
+endif
 
 COMPONENT_ADD_INCLUDEDIRS := include
 
diff --git a/components/pthread/pthread.c b/components/pthread/src/pthread.c
similarity index 96%
rename from components/pthread/pthread.c
rename to components/pthread/src/pthread.c
index 9d7822b8..c9fec073 100644
--- a/components/pthread/pthread.c
+++ b/components/pthread/src/pthread.c
@@ -21,9 +21,11 @@
 #include <errno.h>
 #include <pthread.h>
 #include <string.h>
+#include <stdlib.h>
 #include "esp_err.h"
 #include "esp_attr.h"
-#include "rom/queue.h"
+#include "sys/queue.h"
+#include "sys/types.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/semphr.h"
@@ -31,6 +33,16 @@
 #include "pthread_internal.h"
 #include "esp_pthread.h"
 
+#ifdef CONFIG_ENABLE_PTHREAD
+
+#if portNUM_PROCESSORS == 1
+#undef portENTER_CRITICAL
+#undef portEXIT_CRITICAL
+
+#define portENTER_CRITICAL(l)   vPortEnterCritical()
+#define portEXIT_CRITICAL(l)    vPortExitCritical()
+#endif
+
 #define LOG_LOCAL_LEVEL CONFIG_LOG_DEFAULT_LEVEL
 #include "esp_log.h"
 const static char *TAG = "pthread";
@@ -65,7 +77,9 @@ typedef struct {
 
 
 static SemaphoreHandle_t s_threads_mux  = NULL;
+#if portNUM_PROCESSORS > 1
 static portMUX_TYPE s_mutex_init_lock   = portMUX_INITIALIZER_UNLOCKED;
+#endif
 static SLIST_HEAD(esp_thread_list_head, esp_pthread_entry) s_threads_list
                                         = SLIST_HEAD_INITIALIZER(s_threads_list);
 static pthread_key_t s_pthread_cfg_key;
@@ -73,6 +87,14 @@ static pthread_key_t s_pthread_cfg_key;
 
 static int IRAM_ATTR pthread_mutex_lock_internal(esp_pthread_mutex_t *mux, TickType_t tmo);
 
+static inline void uxPortCompareSet(volatile uint32_t *addr, uint32_t compare, uint32_t *set)
+{
+    portENTER_CRITICAL(&s_mutex_init_lock);
+    *addr = compare;
+    *set = 0;
+    portEXIT_CRITICAL(&s_mutex_init_lock);
+}
+
 static void esp_pthread_cfg_key_destructor(void *value)
 {
     free(value);
@@ -205,7 +227,7 @@ static void pthread_task_func(void *arg)
     }
     xSemaphoreGive(s_threads_mux);
 
-    ESP_LOGD(TAG, "Task stk_wm = %d", uxTaskGetStackHighWaterMark(NULL));
+    ESP_LOGD(TAG, "Task stk_wm = %lu", uxTaskGetStackHighWaterMark(NULL));
     vTaskDelete(NULL);
 
     ESP_LOGV(TAG, "%s EXIT", __FUNCTION__);
@@ -586,3 +608,5 @@ int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type)
     }
     return res;
 }
+
+#endif
diff --git a/components/pthread/pthread_cond_var.c b/components/pthread/src/pthread_cond_var.c
similarity index 97%
rename from components/pthread/pthread_cond_var.c
rename to components/pthread/src/pthread_cond_var.c
index 39e23821..98f53fda 100644
--- a/components/pthread/pthread_cond_var.c
+++ b/components/pthread/src/pthread_cond_var.c
@@ -20,16 +20,19 @@
 #include <errno.h>
 #include <pthread.h>
 #include <string.h>
+#include <stdlib.h>
 #include "esp_err.h"
 #include "esp_attr.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/semphr.h"
-#include "freertos/list.h"
+#include "freertos/private/list.h"
 
-#include <rom/queue.h>
+#include <sys/queue.h>
 #include <sys/time.h>
 
+#ifdef CONFIG_ENABLE_PTHREAD
+
 #define LOG_LOCAL_LEVEL CONFIG_LOG_DEFAULT_LEVEL
 #include "esp_log.h"
 const static char *TAG = "esp_pthread";
@@ -198,3 +201,5 @@ int pthread_cond_destroy(pthread_cond_t *cv)
 
     return ret;
 }
+
+#endif
diff --git a/components/pthread/pthread_internal.h b/components/pthread/src/pthread_internal.h
similarity index 100%
rename from components/pthread/pthread_internal.h
rename to components/pthread/src/pthread_internal.h
diff --git a/components/pthread/pthread_local_storage.c b/components/pthread/src/pthread_local_storage.c
similarity index 96%
rename from components/pthread/pthread_local_storage.c
rename to components/pthread/src/pthread_local_storage.c
index f87f698d..dd10d50e 100644
--- a/components/pthread/pthread_local_storage.c
+++ b/components/pthread/src/pthread_local_storage.c
@@ -14,16 +14,27 @@
 #include <errno.h>
 #include <pthread.h>
 #include <string.h>
+#include <stdlib.h>
 #include "esp_err.h"
 #include "esp_log.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "sys/lock.h"
-#include "rom/queue.h"
+#include "sys/queue.h"
 
 #include "pthread_internal.h"
 
-#define PTHREAD_TLS_INDEX 0
+#ifdef CONFIG_ENABLE_PTHREAD
+
+#define PTHREAD_TLS_INDEX 1
+
+#if portNUM_PROCESSORS == 1
+#undef portENTER_CRITICAL
+#undef portEXIT_CRITICAL
+
+#define portENTER_CRITICAL(l)   vPortEnterCritical()
+#define portEXIT_CRITICAL(l)    vPortExitCritical()
+#endif
 
 typedef void (*pthread_destructor_t)(void*);
 
@@ -42,7 +53,9 @@ typedef struct key_entry_t_ {
 // List of all keys created with pthread_key_create()
 SLIST_HEAD(key_list_t, key_entry_t_) s_keys = SLIST_HEAD_INITIALIZER(s_keys);
 
+#if portNUM_PROCESSORS > 1
 static portMUX_TYPE s_keys_lock = portMUX_INITIALIZER_UNLOCKED;
+#endif
 
 // List of all value entries associated with a thread via pthread_setspecific()
 typedef struct value_entry_t_ {
@@ -255,3 +268,5 @@ int pthread_setspecific(pthread_key_t key, const void *value)
 
     return 0;
 }
+
+#endif
diff --git a/components/pthread/test/test_cxx_cond_var.cpp b/components/pthread/test/test_cxx_cond_var.cpp
deleted file mode 100644
index ccb411ae..00000000
--- a/components/pthread/test/test_cxx_cond_var.cpp
+++ /dev/null
@@ -1,48 +0,0 @@
-#include <iostream>
-#include <thread>
-#include <condition_variable>
-#include <chrono>
-#include <mutex>
-#include <atomic>
-#include "unity.h"
-
-#if __GTHREADS && __GTHREADS_CXX0X
-
-std::condition_variable cv;
-std::mutex cv_m;
-std::atomic<int> i{0};
-
-static void waits(int idx, int timeout_ms)
-{
-    std::unique_lock<std::mutex> lk(cv_m);
-    auto now = std::chrono::system_clock::now();
-
-    if(cv.wait_until(lk, now + std::chrono::milliseconds(timeout_ms), [](){return i == 1;}))
-        std::cout << "Thread " << idx << " finished waiting. i == " << i << '\n';
-    else
-        std::cout << "Thread " << idx << " timed out. i == " << i << '\n';
-}
-
-static void signals(int signal_ms)
-{
-    std::this_thread::sleep_for(std::chrono::milliseconds(signal_ms));
-    std::cout << "Notifying...\n";
-    cv.notify_all();
-    std::this_thread::sleep_for(std::chrono::milliseconds(signal_ms));
-    i = 1;
-    std::cout << "Notifying again...\n";
-    cv.notify_all();
-}
-
-TEST_CASE("C++ condition_variable", "[std::condition_variable]")
-{
-    i = 0;
-    std::thread t1(waits, 1, 100), t2(waits, 2, 800), t3(signals, 200);
-
-    t1.join();
-    t2.join();
-    t3.join();
-
-    std::cout << "All threads joined\n";
-}
-#endif
diff --git a/components/pthread/test/test_cxx_std_future.cpp b/components/pthread/test/test_cxx_std_future.cpp
deleted file mode 100644
index bbf8d624..00000000
--- a/components/pthread/test/test_cxx_std_future.cpp
+++ /dev/null
@@ -1,31 +0,0 @@
-#include <iostream>
-#include <future>
-#include <thread>
-#include "unity.h"
- 
-#if __GTHREADS && __GTHREADS_CXX0X
-TEST_CASE("C++ future", "[std::future]")
-{
-    // future from a packaged_task
-    std::packaged_task<int()> task([]{ return 7; }); // wrap the function
-    std::future<int> f1 = task.get_future();  // get a future
-    std::thread t(std::move(task)); // launch on a thread
- 
-    // future from an async()
-    std::future<int> f2 = std::async(std::launch::async, []{ return 8; });
- 
-    // future from a promise
-    std::promise<int> p;
-    std::future<int> f3 = p.get_future();
-    std::thread( [&p]{ p.set_value_at_thread_exit(9); }).detach();
- 
-    std::cout << "Waiting..." << std::flush;
-    f1.wait();
-    f2.wait();
-    f3.wait();
-    std::cout << "Done!\nResults are: "
-              << f1.get() << ' ' << f2.get() << ' ' << f3.get() << '\n';
-    t.join();
-}
-#endif
-
diff --git a/components/pthread/test/test_pthread_cxx.cpp b/components/pthread/test/test_pthread_cxx.cpp
deleted file mode 100644
index 074b9ba9..00000000
--- a/components/pthread/test/test_pthread_cxx.cpp
+++ /dev/null
@@ -1,132 +0,0 @@
-#include <iostream>
-#include <sstream>
-#include <thread>
-#include <mutex>
-#include "freertos/FreeRTOS.h"
-#include "freertos/task.h"
-#include "unity.h"
-
-#if __GTHREADS && __GTHREADS_CXX0X
-
-#define LOG_LOCAL_LEVEL CONFIG_LOG_DEFAULT_LEVEL
-#include "esp_log.h"
-const static char *TAG = "pthread_test";
-
-static std::shared_ptr<int> global_sp;
-static std::mutex           mtx;
-static std::recursive_mutex recur_mtx;
-
-static void thread_do_nothing() {}
-
-static void thread_main()
-{
-    int i = 0;
-    std::cout << "thread_main CXX " << std::hex <<  std::this_thread::get_id() << std::endl;
-    std::chrono::milliseconds dur = std::chrono::milliseconds(300);
-
-    while (i < 3) {
-        int old_val, new_val;
-
-        // mux test
-        mtx.lock();
-        old_val = *global_sp;
-        std::this_thread::yield();
-        (*global_sp)++;
-        std::this_thread::yield();
-        new_val = *global_sp;
-        mtx.unlock();
-        std::cout << "thread " << std::hex << std::this_thread::get_id() << ": " << i++ << " val= " << *global_sp << std::endl;
-        TEST_ASSERT_TRUE(new_val == old_val + 1);
-
-        // sleep_for test
-        std::this_thread::sleep_for(dur);
-
-        // recursive mux test
-        recur_mtx.lock();
-        recur_mtx.lock();
-        old_val = *global_sp;
-        std::this_thread::yield();
-        (*global_sp)++;
-        std::this_thread::yield();
-        new_val = *global_sp;
-        recur_mtx.unlock();
-        recur_mtx.unlock();
-        std::cout << "thread " << std::hex << std::this_thread::get_id() << ": " << i++ << " val= " << *global_sp << std::endl;
-        TEST_ASSERT_TRUE(new_val == old_val + 1);
-
-        // sleep_until test
-        using std::chrono::system_clock;
-        std::time_t tt = system_clock::to_time_t(system_clock::now());
-        struct std::tm *ptm = std::localtime(&tt);
-        ptm->tm_sec++;
-        std::this_thread::sleep_until(system_clock::from_time_t(mktime(ptm)));
-    }
-}
-
-TEST_CASE("pthread C++", "[pthread]")
-{
-    global_sp.reset(new int(1));
-
-    std::thread t1(thread_do_nothing);
-    t1.join();
-
-    std::thread t2(thread_main);
-    std::cout << "Detach thread " << std::hex << t2.get_id() << std::endl;
-    t2.detach();
-    TEST_ASSERT_FALSE(t2.joinable());
-
-    std::thread t3(thread_main);
-    std::thread t4(thread_main);
-    if (t3.joinable()) {
-        std::cout << "Join thread " << std::hex << t3.get_id() << std::endl;
-        t3.join();
-    }
-    if (t4.joinable()) {
-        std::cout << "Join thread " << std::hex << t4.get_id() << std::endl;
-        t4.join();
-    }
-
-    global_sp.reset(); // avoid reported leak
-}
-
-static void task_test_sandbox()
-{
-    std::stringstream ss;
-
-    ESP_LOGI(TAG, "About to create a string stream");
-    ESP_LOGI(TAG, "About to write to string stream");
-    ss << "Hello World!";
-    ESP_LOGI(TAG, "About to extract from stringstream");
-    ESP_LOGI(TAG, "Text: %s", ss.str().c_str());
-}
-
-static void task_test_sandbox_c(void *arg)
-{
-    bool *running = (bool *)arg;
-
-    // wrap thread func to ensure that all C++ stack objects are cleaned up by their destructors
-    task_test_sandbox();
-
-    ESP_LOGI(TAG, "Task stk_wm = %d", uxTaskGetStackHighWaterMark(NULL));
-    if (running) {
-        *running = false;
-        vTaskDelete(NULL);
-    }
-}
-
-TEST_CASE("pthread mix C/C++", "[pthread]")
-{
-    bool c_running = true;
-
-    std::thread t1(task_test_sandbox);
-    xTaskCreatePinnedToCore((TaskFunction_t)&task_test_sandbox_c, "task_test_sandbox", 3072, &c_running, 5, NULL, 0);
-    while (c_running) {
-        vTaskDelay(1);
-    }
-    if (t1.joinable()) {
-        std::cout << "Join thread " << std::hex << t1.get_id() << std::endl;
-        t1.join();
-    }
-}
-
-#endif
diff --git a/components/pthread/test/test_pthread_local_storage.c b/components/pthread/test/test_pthread_local_storage.c
index 8be22ce5..0b7fe96a 100644
--- a/components/pthread/test/test_pthread_local_storage.c
+++ b/components/pthread/test/test_pthread_local_storage.c
@@ -1,5 +1,6 @@
 // Test pthread_create_key, pthread_delete_key, pthread_setspecific, pthread_getspecific
 #include <pthread.h>
+#include <stdio.h>
 #include "unity.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"