basic_example on esp-12e (nodemcu v1.0) doesn't work

I built the basic_example (_https://github.com/esp8266/source-code-examples.git_) and simply put the following code at the beginning of _user_init_

```
uart_div_modify(0, UART_CLK_FREQ / 115200);

while (true) {
os_printf("Starting\n\r");
os_delay_us(1000000);
}
```

then considering that nodemcu v1.0 uses DIO for SPI flash, I modified the Makefile in two places:

`- $(Q) $(ESPTOOL) elf2image -o $(FW_BASE)/ $(TARGET_OUT)`
`+ $(Q) $(ESPTOOL) elf2image --version=2 -o $(FW_BASE)/fw.bin $(TARGET_OUT)`

in order to obtain a single bin and I added some options to _esptool_ for loading:

`- $(ESPTOOL) --port $(ESPPORT) write_flash $(FW_FILE_1_ADDR) $(FW_FILE_1) $(FW_FILE_2_ADDR) $(FW_FILE_2)`
`+ $(ESPTOOL) --port $(ESPPORT) write_flash -fm dio -fs 32m -ff 40m $(FW_FILE_ADDR) $(FW_BASE)/$(FW_FILE)
`

The program doesn't start up, I expected a periodic printing but I don't get anything.

I tried to load the nodemcu bin with the _esptool_ command and I get a CHECK MEM FAIL even if it does work.