I found the following documents. Command description https://github.com/espressif/esptool/wiki/Advanced-Commands#write_flash_status Source code https://github.com/espressif/esptool/blob/master/esptool.py L3499 def write_flash_status(esp, args) GD25Q32C datasheet http://www.elm-tech.com/ja/products/spi-flash-memory/gd25q32/gd25q32.pdf