Fix original esp32 boot init panic (#3985)

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

arch/esp32/esp32.ini

@@ -1,6 +1,7 @@
 ; Common settings for ESP targes, mixin with extends = esp32_base
 [esp32_base]
 extends = arduino_base
+custom_esp32_kind = esp32
 platform = platformio/espressif32@6.7.0
 
 build_src_filter = 

arch/esp32/esp32c3.ini

@@ -1,5 +1,6 @@
 [esp32c3_base]
 extends = esp32_base
+custom_esp32_kind = esp32c3
 
 monitor_speed = 115200
 monitor_filters = esp32_c3_exception_decoder

arch/esp32/esp32s2.ini

@@ -1,5 +1,6 @@
 [esp32s2_base]
 extends = esp32_base
+custom_esp32_kind = esp32s2
 
 build_src_filter = 
  ${esp32_base.build_src_filter} - <libpax/> -<nimble/> -<mesh/raspihttp>

arch/esp32/esp32s3.ini

@@ -1,5 +1,6 @@
 [esp32s3_base]
 extends = esp32_base
+custom_esp32_kind = esp32s3
 
 monitor_speed = 115200
 

bin/platformio-custom.py

@@ -62,7 +62,21 @@ if platform.name == "espressif32":
     import esptool
 
     env.AddPostAction("$BUILD_DIR/${PROGNAME}.bin", esp32_create_combined_bin)
-    env.Append(LINKFLAGS=["--specs=nano.specs", "-u", "_printf_float"])
+
+    esp32_kind = env.GetProjectOption("custom_esp32_kind")
+    if esp32_kind == "esp32":
+        # Free up some IRAM by removing auxiliary SPI flash chip drivers.
+        # Wrapped stub symbols are defined in src/platform/esp32/iram-quirk.c.
+        env.Append(
+            LINKFLAGS=[
+                "-Wl,--wrap=esp_flash_chip_gd",
+                "-Wl,--wrap=esp_flash_chip_issi",
+                "-Wl,--wrap=esp_flash_chip_winbond",
+            ]
+        )
+    else:
+        # For newer ESP32 targets, using newlib nano works better.
+        env.Append(LINKFLAGS=["--specs=nano.specs", "-u", "_printf_float"])
 
 Import("projenv")
 

src/platform/esp32/iram-quirk.c

@@ -0,0 +1,23 @@
+// Free up some precious space in the iram0_0_seg memory segment
+
+#include <stdint.h>
+
+#include <esp_attr.h>
+#include <esp_flash.h>
+#include <spi_flash_chip_driver.h>
+
+#define IRAM_SECTION section(".iram1.stub")
+
+IRAM_ATTR esp_err_t stub_probe(esp_flash_t *chip, uint32_t flash_id)
+{
+    return ESP_ERR_NOT_FOUND;
+}
+
+const spi_flash_chip_t stub_flash_chip __attribute__((IRAM_SECTION)) = {
+    .name = "stub",
+    .probe = stub_probe,
+};
+
+extern const spi_flash_chip_t __wrap_esp_flash_chip_gd __attribute__((IRAM_SECTION, alias("stub_flash_chip")));
+extern const spi_flash_chip_t __wrap_esp_flash_chip_issi __attribute__((IRAM_SECTION, alias("stub_flash_chip")));
+extern const spi_flash_chip_t __wrap_esp_flash_chip_winbond __attribute__((IRAM_SECTION, alias("stub_flash_chip")));