Gadget.yaml fields

The available fields of the gadget.yaml file are defined in snapd/gadget/gadget.go.

A description is provided in the Gadget.yaml section of the Gadget snaps specification.

Here is a list the relevant part of the field hierarchy as of Snapd 2.67:

-volumes,omitempty (map[string]*Volume)
 |-<Key> (string)
 | <Value> (*Volume)
 | |-schema (string) enum:emmc,gpt,mbr
 | |-bootloader (string) enum:android-boot,grub,lk,piboot
 | |-id (string)
 | |-structure ([]VolumeStructure)
 | | |-name (string)
 | | |-type (string)
 | | |-filesystem (string) enum:ext4,vfat,vfat-16,vat-32
 | | |-filesystem-label (string)
 | | |-min-size (Size)
 | | |-size (Size)
 | | |-offset (*Offset)
 | | |-offset-write (*RelativeOffset)
 | | | |-relative-to (string)
 | | | |-offset (Offset)
 | | |-role (string) enum:system-boot,system-data,system-seed,system-seed-null,system-save
 | | |-id (string)
 | | |-content ([]VolumeContent)
 | | | |-source (string)
 | | | |-target (string)
 | | | |-image (string)
 | | | |-offset (*Offset)
 | | | |-size (Size)
 | | | |-unpack (bool)

The type field can have as value:

• The string bare. This indicates an unformatted partition, e.g. for placing firmware.

• A two digit partition type for MBR partition tables, e.g. EF

• A partition type GUID for GPT partition tables, e.g. C12A7328-F81F-11D2-BA4B-00A0C93EC93B

• a combination of MBR and GPT partition type e.g. EF,C12A7328-F81F-11D2-BA4B-00A0C93EC93B

Size, min.size, and offset fields can use an ‘M’ or ‘G’ postfix to indicate mebibytes or gibibytes. The following would be valid values for size:

• 1048576

• 4M

• 16G

Here is an example:

---
volumes:
  riscv:
    schema: gpt
    bootloader: grub
    structure:
      - name: starfive_visionfive_2_u-boot-spl
        type: 2E54B353-1271-4842-806F-E436D6AF6985
        size: 1M
        content:
          - image: u-boot-starfive/u-boot-spl.bin.normal.out
      - name: starfive_visionfive_2_u-boot
        # random value for type
        type: 816E2DB1-6FE4-4797-B3FF-2DE37CB85318
        size: 16M
        content:
          - image: u-boot-starfive/u-boot.itb
      - name: EFI System
        type: C12A7328-F81F-11D2-BA4B-00A0C93EC93B
        filesystem: vfat
        filesystem-label: esp
        size: 100M
        role: system-boot
        content:
          - source: grub/grubriscv64.efi
            target: EFI/boot/bootriscv64.efi
          - source: grub/grubriscv64.efi
            target: EFI/ubuntu/grubriscv64.efi
          - source: grub/grub.cfg
            target: EFI/debian/grub.cfg
          - source: grub/grub.cfg
            target: EFI/ubuntu/grub.cfg
          - source: dtb/
            target: dtb/
      - name: CIDATA
        type: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
        filesystem: vfat-16
        filesystem-label: CIDATA
        size: 4M
        content:
          - source: cidata/meta-data
            target: meta-data
          - source: cidata/user-data
            target: user-data
      - name: Root Partition
        type: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
        filesystem: ext4
        filesystem-label: writable
        size: 3072M
        role: system-data