Disable serial output from bootrom

[pabloko]

Hey, ive seen your awesome development at bootrom disassembly, as im not very aware with this processor arch, im looking for a way to disable the bootrom output, at least the bootrom log that is sent during boot.

As i see the main method has this logic 40001069: 054601 call0 400024cc <ets_printf>

What comes to my mind is to edit those first string sent to ets_printf setting first byte to null, which dont require to hex edit, reassamble or or bootrom modification (i dont know if this part is even writable)

3fffd674     db      '\n ets %s,rst cause:%d, boot mode:(%d,%d)\n\n\0'
3fffd700     db      'load 0x%08x, len %d, room %d \n\0'
3fffd734     db      'tail %d\n\0'
3fffd740     db      'chksum 0x%02x\n\0'
...

So just writing a '\0' on the first byte of each string should silence the bootup process

Im not very sure about this processor arch, and how to do it, and not even sure this part is even writable, im total noob on this ic developing, maybe you can help me out with this?

Maybe esptool can be used to just write that bytes? or even using the spi_flash_read/write from bootrom in a custom firmware (https://github.com/sheinz/esp-spi-flash-test)

Regards