feat(esp8266): Avoid to NMI calling ets_printf crash

components/esp8266/Kconfig

@@ -92,6 +92,21 @@ config LINK_ETS_PRINTF_TO_IRAM
 
         Note: Bootloader can't use this function.
 
+config ETS_PRINTF_EXIT_WHEN_FLASH_RW
+    bool "ets_printf exits when flash R/W"
+    default y
+    depends on !LINK_ETS_PRINTF_TO_IRAM
+    help
+        By default option, we link the ets_printf function and its calling functions
+        in SPI Flash. So when the SPI Flash is working in read/write mode, and we
+        call ets_printf in high level interrupt like NMI, this behavior will cause a
+        crash, and the EXCCAUSE=0.
+
+        Enable this option, we link the ets_printf in IRAM, and its calling functions
+        in SPI Flash. In the entry of ets_printf, we check if the SPI Flash is working
+        in read/write mode, and exit if it is. So that ets_printf will not call functions
+        in SPI Flash.
+
 config SOC_FULL_ICACHE
     bool "Enable full cache mode"
     default n

components/esp8266/source/ets_printf.c

@@ -24,6 +24,12 @@
 #include "esp8266/uart_register.h"
 #include "esp8266/rom_functions.h"
 
+#ifdef CONFIG_ETS_PRINTF_EXIT_WHEN_FLASH_RW
+#define ETS_PRINTF_ATTR IRAM_ATTR
+#else
+#define ETS_PRINTF_ATTR
+#endif
+
 #ifndef CONFIG_ESP_CONSOLE_UART_NONE
 static void uart_putc(int c)
 {
@@ -285,11 +291,19 @@ int ets_vprintf(const char *fmt, va_list ap)
  *                            "%s": 172 Bytes
  *      "%p", "%d, "%i, "%u", "%x": 215 Bytes
  */
-int ets_printf(const char *fmt, ...)
+int ETS_PRINTF_ATTR ets_printf(const char *fmt, ...)
 {
     va_list ap;
     int ret;
 
+#ifdef CONFIG_ETS_PRINTF_EXIT_WHEN_FLASH_RW
+    extern uint8_t FlashIsOnGoing;
+
+    if (FlashIsOnGoing) {
+        return -1;
+    }
+#endif
+
     va_start(ap, fmt);
     ret = ets_vprintf(fmt, ap);
     va_end(ap);