.platformio/packages/framework-arduinoespressif32/cores/esp32
esp32-hal-log.h:int log_printf(const char *fmt, ...);
esp32-hal-log.h:#define log_v(format, ...) log_printf(ARDUHAL_LOG_FORMAT(V, format), ##__VA_ARGS__)
esp32-hal-log.h:#define log_d(format, ...) log_printf(ARDUHAL_LOG_FORMAT(D, format), ##__VA_ARGS__)
esp32-hal-log.h:#define log_i(format, ...) log_printf(ARDUHAL_LOG_FORMAT(I, format), ##__VA_ARGS__)
esp32-hal-log.h:#define log_w(format, ...) log_printf(ARDUHAL_LOG_FORMAT(W, format), ##__VA_ARGS__)
esp32-hal-log.h:#define log_e(format, ...) log_printf(ARDUHAL_LOG_FORMAT(E, format), ##__VA_ARGS__)
esp32-hal-uart.c:int log_printf(const char *format, ...)

.platformio/packages/framework-arduinoespressif32/tools/sdk/include/config
--- sdkconfig.h.orig    2017-11-13 14:51:26.776375400 +0100
+++ sdkconfig.h 2017-11-13 14:52:09.400429500 +0100
@@ -58,7 +58,7 @@
 #define CONFIG_NUMBER_OF_UNIVERSAL_MAC_ADDRESS 4
 #define CONFIG_ESPTOOLPY_FLASHSIZE_DETECT 1
 #define CONFIG_AUTOSTART_ARDUINO 1
-#define CONFIG_LOG_DEFAULT_LEVEL_ERROR 1
+#define CONFIG_LOG_DEFAULT_LEVEL_VERBOSE 1
 #define CONFIG_ESP32_ENABLE_COREDUMP_TO_NONE 1
 #define CONFIG_BTDM_CONTROLLER_RUN_CPU 0
 #define CONFIG_TCPIP_TASK_STACK_SIZE 2560
@@ -71,7 +71,7 @@
 #define CONFIG_BTC_TASK_STACK_SIZE 8192
 #define CONFIG_BLUEDROID_ENABLED 1
 #define CONFIG_ESPTOOLPY_BEFORE "default_reset"
-#define CONFIG_LOG_DEFAULT_LEVEL 1
+#define CONFIG_LOG_DEFAULT_LEVEL 5
 #define CONFIG_TIMER_QUEUE_LENGTH 10
 #define CONFIG_ESP32_WIFI_DYNAMIC_RX_BUFFER_NUM 0
 #define CONFIG_ESP32_PHY_MAX_WIFI_TX_POWER 20
@@ -103,12 +103,12 @@
 #define CONFIG_BROWNOUT_DET 1
 #define CONFIG_ESP32_XTAL_FREQ 0
 #define CONFIG_MONITOR_BAUD_115200B 1
-#define CONFIG_LOG_BOOTLOADER_LEVEL 0
+#define CONFIG_LOG_BOOTLOADER_LEVEL 5
 #define CONFIG_SMP_ENABLE 1
 #define CONFIG_ESPTOOLPY_BEFORE_RESET 1
 #define CONFIG_ESPTOOLPY_BAUD_OTHER_VAL 115200
 #define CONFIG_ENABLE_ARDUINO_DEPENDS 1
-#define CONFIG_LOG_BOOTLOADER_LEVEL_NONE 1
+#define CONFIG_LOG_BOOTLOADER_LEVEL_VERBOSE 1
 #define CONFIG_ESP32_DEFAULT_CPU_FREQ_240 1
 #define CONFIG_ESP32_XTAL_FREQ_AUTO 1
 #define CONFIG_TCP_MAXRTX 12

Honor the ESP_LOGx logging macros
Commit: Implement ESP_LOGx override option

An Arduino library for logging to Syslog server in IETF format (RFC 5424) and BSD format (RFC 3164)
Hardware: ESP8266 / ESP32 / Arduino Ethernet / etc.
github.com/arcao/Syslog

Logging library for Arduino, by LunaX – 2010/2011