build_library/nand_disk_layout.json

{
  "metadata":{
    "rootdev_base": "/dev/mtd0",
    "block_size": 512,
    "fs_block_size": 4096
  },
  "layouts":{
    "common":[
      {
        "num": 6,
        "label":"KERN-C",
        "type":"blank",
        "size":"0"
      },
      {
        "num": 7,
        "label":"ROOT-C",
        "type":"blank",
        "size":"0"
      },
      {
        "num": 2,
        "label":"KERN-A",
        "type":"kernel"
      },
      {
        "num": 4,
        "label":"KERN-B",
        "type":"kernel"
      },
      {
        "num": 8,
        "label":"OEM",
        "type":"data",
        "fs_format":"ext4",
        "uuid": "random"
      },
      {
        # Used for Legacy Bios, and EFI Bios, not Chrome OS hardware.
        "num": 12,
        "label": "EFI-SYSTEM",
        "type": "efi",
        "fs_format": "vfat",
        "size": "16 MiB",
        "uuid": "clear"
      },
      {
        "num": 5,
        "label":"ROOT-B",
        "type":"rootfs",
        "fs_format":"ext2",
        "uuid": "random"
      },
      {
        "num": 3,
        "label":"ROOT-A",
        "type":"rootfs",
        "fs_format":"ext2",
        "uuid": "random"
      },
      {
        "num": 1,
        "label": "STATE",
        "type": "data",
        "fs_format": "ext4",
        "uuid": "random"
      }
    ],
    "base":[
      {
        "num": "metadata",
        "external_gpt": true
      },
      {
        "num": 2,
        "format": "nand"
      },
      {
        "num": 4,
        "format": "nand"
      },
      {
        "num": 12,
        "label":"EFI-SYSTEM",
        "type":"blank",
        "size":"0"
      },
      {
        "num": 5,
        "format":"ubi"
      },
      {
        "num": 3,
        "format":"ubi"
      },
      {
        "num": 1,
        "format": "ubi",
        "fs_format": "ubifs"
      },
      # BBT partition exists just to hold a few blocks open for
      # the bad block table.
      {
        "num": 13,
        "label": "BBT",
        "size": 0,
        "type": "blank",
        "reserved_erase_blocks": 4
      }
    ],
    "usb": [
      {
        "num": 1,
        "features": ["expand"]
      }
    ],
    "factory_install": [
      {
        "num": 12,
        "size": "32 MiB"
      },
      {
        "num": 5,
        "size": "2 MiB"
      },
      {
        "num": 3,
        "size": "420 MiB",
        "fs_size": "400 MiB"
      },
      {
        "num": 1,
        "size": "140 MiB"
      }
    ],
    "recovery": [
      {
        # Slot B rootfs, unused on USB, but pad to 2M.
        # installation will expand this to size from base.
        "num": 5,
        "size": "2 MiB"
      },
      {
        # Shrunken rootfs partition to support smaller USB sticks,
        # and smaller recovery downloads.
        # Installation will expand this to size from base.
        # The offset to the beginning of this partition, and the FS
        # size must match base exactly to allow secure boot.
        "num": 3,
        "size": "1290 MiB"
      },
      {
        # Stateful on recovery is dynamically resized larger.
        "num": 1,
        "size": "2 MiB"
      }
    ]
  }
}