Merge branch 'bugfix/dont_log_before_bss_inited' into 'master'

Remove ESP_EARLY_LOGI before bss is initialized; it crashes the CPU



There's an ESP_EARLY_LOGI line that can get called before the BSS is initialized; the early logging code doesn't cope well with that: it checks if FreeRTOS is up, but the variables it uses for that contains garbage because it isn't cleared yet, giving the wrong result. The logging code then tries to set a mux, crashing the entire system. This patch removes the log line and adds a warning at the BSS initialization line not to do anything complex before that point.



Fixes https://github.com/espressif/esp-idf/issues/523



See merge request !671

components/esp32/cpu_start.c

@@ -112,6 +112,7 @@ void IRAM_ATTR call_start_cpu0()
 #if !CONFIG_FREERTOS_UNICORE
     rst_reas[1] = rtc_get_reset_reason(1);
 #endif
+
     // from panic handler we can be reset by RWDT or TG0WDT
     if (rst_reas[0] == RTCWDT_SYS_RESET || rst_reas[0] == TG0WDT_SYS_RESET
 #if !CONFIG_FREERTOS_UNICORE
@@ -119,10 +120,10 @@ void IRAM_ATTR call_start_cpu0()
 #endif
         ) {
         // stop wdt in case of any
-        ESP_EARLY_LOGI(TAG, "Stop panic WDT");
         esp_panic_wdt_stop();
     }
 
+    //Clear BSS. Please do not attempt to do any complex stuff (like early logging) before this.
     memset(&_bss_start, 0, (&_bss_end - &_bss_start) * sizeof(_bss_start));
 
     /* Unless waking from deep sleep (implying RTC memory is intact), clear RTC bss */
@@ -130,7 +131,6 @@ void IRAM_ATTR call_start_cpu0()
         memset(&_rtc_bss_start, 0, (&_rtc_bss_end - &_rtc_bss_start) * sizeof(_rtc_bss_start));
     }
 
-
     ESP_EARLY_LOGI(TAG, "Pro cpu up.");
 
 #if !CONFIG_FREERTOS_UNICORE