arch/Kconfig: Bring-up features should also depend on CONFIG_DEBUG_FEATURES. I missed a bring-up feature that is specific to the ESP32. I hope that the ESP32 ports still work as intended! It depended on some of these bring-up settings in the header file. I moved the definitions to the ESP32 defconfig files.

arch/Kconfig

@@ -697,10 +697,19 @@ config ARCH_NUSER_INTERRUPTS
 
 # Bring-up debug configuration options.  These are only intended for low level
 # bring-up and not part of normal platform configuration.  They should never be
-# selected in a "normal" configuration and, hence, depend on EXPERIMENTAL
+# selected in a "normal" configuration and, hence, depend on both EXPERIMENTAL
+# and DEBUG_FEATURES.
 
 menu "Bring-Up Options"
-	depends on EXPERIMENTAL
+	depends on EXPERIMENTAL && DEBUG_FEATURES
+
+config SUPPRESS_CLOCK_CONFIG
+	bool "Suppress clock configuration"
+	default n
+	depends on ARCH_XTENSA
+	---help---
+		Do not configure clocking.  Instead relies on the reset clock
+		configuration (or clock configuration provided by a bootloader).
 
 config SUPPRESS_INTERRUPTS
 	bool "Suppress all interrupts"

configs/esp32-core/README.txt

@@ -16,7 +16,6 @@ README for the Expressif ESP32 Core board (V2)
 Contents
 ========
 
-  o STATUS
   o ESP32 Features
   o ESP32 Toolchain
   o Memory Map
@@ -31,7 +30,19 @@ Contents
 STATUS
 ======
 
-  The basic port is underway.  No testing has yet been performed.
+  Currently, the NuttX port depends on the bootloader to initialize hardware,
+  including basic (slow) clocking.  That is because the clock configuration
+  logic is only available via an Espressif add-on library.
+
+  Because of this, all board configurations require these settings:
+
+    CONFIG_EXPERIMENTAL=y
+    CONFIG_DEBUG_FEATURES=y
+    CONFIG_SUPPRESS_CLOCK_CONFIG=y
+
+  Some configurations may also require:
+
+    CONFIG_SUPPRESS_UART_CONFIG=y
 
 ESP32 Features
 ==============
@@ -527,22 +538,11 @@ OpenOCD for the ESP32
     CONFIG_DEBUG_SYMBOLS=y
     CONFIG_ESP32CORE_RUN_IRAM=y
 
-  I also made this change which will eliminate all attempts to re-configure
-  serial. It will just use the serial settings as they were left by the
-  bootloader:
+  I also made this change configuration which will eliminate all attempts to
+  re-configure serial. It will just use the serial settings as they were left
+  by the bootloader:
 
-    diff --git a/arch/xtensa/src/common/xtensa.h b/arch/xtensa/src/common/xtensa.h
-    index 422ec0b..8707d7c 100644
-    --- a/arch/xtensa/src/common/xtensa.h
-    +++ b/arch/xtensa/src/common/xtensa.h
-    @@ -60,7 +60,7 @@
-     #undef  CONFIG_SUPPRESS_INTERRUPTS     /* DEFINED: Do not enable interrupts */
-     #undef  CONFIG_SUPPRESS_TIMER_INTS     /* DEFINED: No timer */
-     #undef  CONFIG_SUPPRESS_SERIAL_INTS    /* DEFINED: Console will poll */
-    -#undef  CONFIG_SUPPRESS_UART_CONFIG    /* DEFINED: Do not reconfigure UART */
-    +#define CONFIG_SUPPRESS_UART_CONFIG  1 /* DEFINED: Do not reconfigure UART */
-     #define CONFIG_SUPPRESS_CLOCK_CONFIG 1 /* DEFINED: Do not reconfigure clocking */
-     #undef  CONFIG_DUMP_ON_EXIT            /* DEFINED: Dump task state on exit */
+    CONFIG_SUPPRESS_UART_CONFIG=y
 
   Start OpenOCD:
 
@@ -735,18 +735,11 @@ Things to Do
      This will use the serial port settings as left by the preceding
      bootloader:
 
-     diff --git a/arch/xtensa/src/common/xtensa.h b/arch/xtensa/src/common/xtensa.h
-     index 422ec0b..8707d7c 100644
-     --- a/arch/xtensa/src/common/xtensa.h
-     +++ b/arch/xtensa/src/common/xtensa.h
-     @@ -60,7 +60,7 @@
-      #undef  CONFIG_SUPPRESS_INTERRUPTS     /* DEFINED: Do not enable interrupts */
-      #undef  CONFIG_SUPPRESS_TIMER_INTS     /* DEFINED: No timer */
-      #undef  CONFIG_SUPPRESS_SERIAL_INTS    /* DEFINED: Console will poll */
-     -#undef  CONFIG_SUPPRESS_UART_CONFIG    /* DEFINED: Do not reconfigure UART */
-     +#define CONFIG_SUPPRESS_UART_CONFIG  1 /* DEFINED: Do not reconfigure UART */
-      #define CONFIG_SUPPRESS_CLOCK_CONFIG 1 /* DEFINED: Do not reconfigure clocking */
-      #undef  CONFIG_DUMP_ON_EXIT            /* DEFINED: Dump task state on exit */
+     I also made this change configuration which will eliminate all attempts to
+     re-configure serial. It will just use the serial settings as they were left
+     by the bootloader:
+
+       CONFIG_SUPPRESS_UART_CONFIG=y
 
      I have not debugged this in detail, but this appears to be an issue with the
      impelentation of esp32_configgpio() and/or gpio_matrix_out() when called from

configs/esp32-core/nsh/defconfig

@@ -10,6 +10,7 @@ CONFIG_ARCH_XTENSA=y
 CONFIG_ARCH="xtensa"
 CONFIG_BOARD_LOOPSPERMSEC=16717
 CONFIG_BUILTIN=y
+CONFIG_DEBUG_FEATURES=y
 CONFIG_DISABLE_POLL=y
 CONFIG_ESP32_UART0=y
 CONFIG_SYSTEM_NSH_CXXINITIALIZE=y

configs/esp32-core/ostest/defconfig

@@ -6,6 +6,7 @@ CONFIG_ARCH_XTENSA=y
 CONFIG_ARCH="xtensa"
 CONFIG_BOARD_LOOPSPERMSEC=16717
 CONFIG_BUILTIN=y
+CONFIG_DEBUG_FEATURES=y
 CONFIG_DISABLE_POLL=y
 CONFIG_ESP32_UART0=y
 CONFIG_EXAMPLES_OSTEST_LOOPS=10

configs/esp32-core/smp/defconfig

@@ -10,6 +10,7 @@ CONFIG_ARCH_XTENSA=y
 CONFIG_ARCH="xtensa"
 CONFIG_BOARD_LOOPSPERMSEC=16717
 CONFIG_BUILTIN=y
+CONFIG_DEBUG_FEATURES=y
 CONFIG_DISABLE_POLL=y
 CONFIG_ESP32_UART0=y
 CONFIG_EXPERIMENTAL=y