esp-idf/examples/storage/parttool/partitions_example.csv

# Name,   Type, SubType, Offset,  Size, Flags
# Note: if you have increased the bootloader size, make sure to update the offsets to avoid overlap
nvs,      data, nvs,     0x9000,  0x6000,
phy_init, data, phy,     0xf000,  0x1000,
factory,  app,  factory, 0x10000, 1M,
custom,   data, nvs,     ,        0x1000,
storage,  data, spiffs,  ,        0x10000,