Merge branch 'esp8266-wrap-printf' into integration

esphome/components/esp8266/__init__.py

@@ -23,6 +23,7 @@ from esphome.helpers import copy_file_if_changed
 from .boards import BOARDS, ESP8266_LD_SCRIPTS
 from .const import (
     CONF_EARLY_PIN_INIT,
+    CONF_ENABLE_FULL_PRINTF,
     CONF_ENABLE_SERIAL,
     CONF_ENABLE_SERIAL1,
     CONF_RESTORE_FROM_FLASH,
@@ -179,6 +180,7 @@ CONFIG_SCHEMA = cv.All(
             ),
             cv.Optional(CONF_ENABLE_SERIAL): cv.boolean,
             cv.Optional(CONF_ENABLE_SERIAL1): cv.boolean,
+            cv.Optional(CONF_ENABLE_FULL_PRINTF, default=False): cv.boolean,
         }
     ),
     set_core_data,
@@ -260,10 +262,13 @@ async def to_code(config):
     if CORE.testing_mode:
         cg.add_build_flag("-DESPHOME_TESTING_MODE")
 
-    # Wrap FILE*-based printf functions to eliminate newlib's _vfprintf_r
-    # (~900 bytes). See printf_stubs.cpp for implementation.
-    for symbol in ("vprintf", "printf", "fprintf"):
-        cg.add_build_flag(f"-Wl,--wrap={symbol}")
+    # Wrap FILE*-based printf functions to eliminate newlib's _vfiprintf_r
+    # (~1.6 KB). See printf_stubs.cpp for implementation.
+    if config.get(CONF_ENABLE_FULL_PRINTF):
+        cg.add_define("USE_FULL_PRINTF")
+    else:
+        for symbol in ("vprintf", "printf", "fprintf"):
+            cg.add_build_flag(f"-Wl,--wrap={symbol}")
 
     cg.add_platformio_option("board_build.flash_mode", config[CONF_BOARD_FLASH_MODE])
 

esphome/components/esp8266/const.py

@@ -6,6 +6,7 @@ KEY_BOARD = "board"
 KEY_PIN_INITIAL_STATES = "pin_initial_states"
 CONF_RESTORE_FROM_FLASH = "restore_from_flash"
 CONF_EARLY_PIN_INIT = "early_pin_init"
+CONF_ENABLE_FULL_PRINTF = "enable_full_printf"
 CONF_ENABLE_SERIAL = "enable_serial"
 CONF_ENABLE_SERIAL1 = "enable_serial1"
 KEY_FLASH_SIZE = "flash_size"

esphome/components/esp8266/printf_stubs.cpp

@@ -3,14 +3,14 @@
  *
  * The ESP8266 Arduino framework and libraries may reference printf(),
  * vprintf(), and fprintf() which pull in newlib's _vfprintf_r (~900 bytes).
- * ESPHome never uses these — all logging goes through ets_printf/ets_vsnprintf
- * directly, so the libc FILE*-based printf path is dead code.
+ * ESPHome never uses these — all logging writes directly to the UART via
+ * Arduino's Serial, so the libc FILE*-based printf path is dead code.
  *
  * These stubs redirect through vsnprintf() (which is already in the binary
  * for ESPHome's logging) and fwrite(), allowing the linker to dead-code
  * eliminate _vfprintf_r.
  *
- * Saves ~900 bytes of flash.
+ * Saves ~1.6 KB of flash.
  */
 
 #if defined(USE_ESP8266) && !defined(USE_FULL_PRINTF)
@@ -20,10 +20,10 @@
 
 namespace esphome::esp8266 {}
 
-static constexpr size_t PRINTF_BUFFER_SIZE = 256;
+static constexpr size_t PRINTF_BUFFER_SIZE = 512;
 
-// These stubs are essentially dead code at runtime — ESPHome uses ets_printf
-// for logging, and the Arduino core's Serial.printf() has its own implementation.
+// These stubs are essentially dead code at runtime — ESPHome writes directly
+// to the UART via Arduino's Serial, and Serial.printf() has its own implementation.
 // The buffer overflow check is purely defensive and should never trigger.
 static int write_printf_buffer(FILE *stream, char *buf, int len) {
   if (len < 0) {

tests/components/esp8266/test.esp8266-ard.yaml

@@ -1,3 +1,6 @@
+esp8266:
+  enable_full_printf: false
+
 logger:
   level: VERBOSE