feat(system_init): introduce pre-scheduler and pre-app main handler registrations

- Added macros for registering handlers to run before the scheduler and app main.
- Updated various components to utilize the new registration system for initialization.
- Refactored app startup logic to streamline initialization sequence.

components/esp_gdbstub/CMakeLists.txt

@@ -34,3 +34,12 @@ if(CONFIG_ESP_SYSTEM_PANIC_GDBSTUB)
     # Make sure the panic event registration in gdbstub.c is considered by the linker
     target_link_libraries(${COMPONENT_LIB} INTERFACE "-u esp_gdbstub_panic_handler")
 endif()
+
+if(CONFIG_ESP_SYSTEM_GDBSTUB_RUNTIME)
+    # Pull in the PRE_SCHEDULER registration from gdbstub.c.
+    target_link_libraries(${COMPONENT_LIB} INTERFACE "-u esp_gdbstub_init")
+    if(CONFIG_IDF_TARGET_ARCH_XTENSA)
+        # Pull in the Xtensa debug exception handler from its separate object file.
+        target_link_libraries(${COMPONENT_LIB} INTERFACE "-u _xt_panic_gdbstub")
+    endif()
+endif()

components/esp_gdbstub/src/gdbstub.c

@@ -25,6 +25,7 @@
 #endif
 
 #include "esp_private/esp_sys_event_panic.h"
+#include "esp_private/esp_sys_event_app_init.h"
 #include "esp_private/panic_internal.h"
 #include "esp_private/crosscore_int.h"
 
@@ -451,6 +452,14 @@ void esp_gdbstub_init(void)
     esp_intr_alloc(ETS_UART0_INTR_SOURCE, 0, esp_gdbstub_int, NULL, NULL);
     esp_gdbstub_init_dports();
 }
+
+ESP_PRE_SCHEDULER_HANDLER_REGISTER(init_gdbstub, 130)
+{
+    (void)user_arg;
+    (void)ctx;
+    esp_gdbstub_init();
+    return ESP_OK;
+}
 #endif /* CONFIG_ESP_SYSTEM_GDBSTUB_RUNTIME */
 
 #ifdef CONFIG_ESP_GDBSTUB_SUPPORT_TASKS