src/developer/ffx/plugins/assembly/README.md - fuchsia - Git at Google

 # FFX Plugin for Product and Image Assembly

 TODO: Document Product Assembly

 [Image Assembly RFC-0072](/docs/contribute/governance/rfcs/0072_standalone_image_assembly_tool.md).

 Image Assembly is responsible for taking prebuilt artifacts and generating
 images that can be used to update or flash a Fuchsia device. The FFX plugin has
 three subcommands: [`create-system`](#create_system),
 [`create-update`](#create_update), and
 [`create-flash-manifest`](#create_flash_manifest).

 ![Command Flow](images/commands.png)

 # create-system

 Create a Fuchsia system that minimally includes a ZBI, and optionally a VBMeta
 and FVM images.

 ```bash
 ffx assembly create-system                           \
   --image-assembly-config image_assembly_config.json \
   --images images_config.json                        \
   --outdir <output-directory>
 ```

 ## Arguments

 | input | format | description |
 | --- | --- | --- |
 | `--image-assembly-config` | [Image Assembly Config](#image-assembly-config) | Contents of the Fuchsia system that are put into the images. |
 | `--images` | [Images Config](#images-config) | Which images to generate and how. |
 | `--outdir` | path | Directory to write outputs. |
 | `--gendir` | path | (optional; default=outdir) Directory to write intermediate files. |
 | `--base-package-name` | string | (optional; default="system_image") Name to give the Base Package. This is currently only used by OTA tests to allow publishing muliple base packages to the same amber repository without naming collisions. |
 | `--mode` | [Modes](#modes) | (optional; default="standard") Where to put the packages. |

 ## Modes

 | mode | description |
 | --- | --- |
 | `standard` | Packages are placed in a blobfs in a FVM that is flashed to a separate partition. |
 | `fvm_in_zbi` | Packages are placed in a blobfs in a FVM that is embedded into the ZBI as a ramdisk. |
 | `bootfs_only` | Packages are placed into BootFS. |

 ## Outputs

 | output | format | description |
 | --- | --- | --- |
 | `packages.json` | [Package Manifest](/docs/concepts/packages/update_pkg.md) | List of packages in the system. |
 | `images.json` | [Images Manifest](#images-manifest) | List of images generated. |
 | `fuchsia.zbi` | | Fuchsia Zircon Boot Image (ZBI). |
 | `fuchsia.vbmeta` | | Fuchsia Verified Boot Metadata (VBMeta). |
 | `fvm.blk` | | Fuchsia Volume Manager (FVM). |

 # create-update

 Create an update package for updating a running Fuchsia system.

 ```bash
 ffx assembly create-update                    \
   --packages packages.json                    \
   --partitions partitions.json                \
   --system-a images.json                      \
   --system-r recovery_images.jso              \
   --board-name "board"                        \
   --version-file version.txt                  \
   --epoch 0                                   \
   --outdir <output-directory>
 ```

 ## Arguments

 input                   | format                                                     | description
 ----------------------- | ---------------------------------------------------------  | -----------
 `--packages`            | [Package Manifest](/docs/concepts/packages/update_pkg.md)  | List of packages in the system.
 `--partitions`          | [Partitions Config](#partitions-config)                    | Where in the partition table the images are put.
 `--system-[a,b,r]`      | [Images Manifest](#images-manifest)                        | The system to place in the slot.
 `--board-name`          | string                                                     | The name of the board. Fuchsia will reject an Update Package with a different board name.
 `--version-file`        | path of file containing `a.b.c.d`, where each digit is u32 | The file containing the version of the Fuchsia system.
 `--epoch`               | int                                                        | The backstop OTA version. Fuchsia will reject updates with a lower epoch.
 `--outdir`              | path                                                       | Directory to write outputs.
 `--gendir`              | path                                                       | (optional; default=outdir) Directory to write intermediate files.
 `--update-package-name` | string                                                     | (optional; default="update") Name to give the Update Package. This is currently only used by OTA tests to allow publishing multiple update packages to the same amber repository without naming collisions.

 ## Outputs

 output       | format                                          | description
 ------------ | ----------------------------------------------- | ---------------
 `update.far` | [Format](/docs/concepts/packages/update_pkg.md) | Update package.

 # create-flash-manifest

 Create a manifest file that describes how to flash images onto a Fuchsia device.

 ```bash
 ffx assembly create-flash-manifest \
   --partitions partitions.json     \
   --system-a images.json           \
   --system-b images.json           \
   --system-r recovery_images.json  \
   --outdir <output-directory>
 ```

 ## Arguments

 | input | format | description |
 | --- | --- | --- |
 | `--partitions` | [Partitions Config](#partitions-config) | Where in the partition table the images are put. |
 | `--system-[a,b,r]` | [Images Manifest](#images-manifest) | The system to place in the slot. |
 | `--outdir` | path | Directory to write outputs. |

 ## Output

 output       | format                                                                                       | description
 ------------ | -------------------------------------------------------------------------------------------- | -----------
 `flash.json` | [RFC-0100](https://fuchsia.dev/fuchsia-src/contribute/governance/rfcs/0100_product_metadata) | Flash manifest that specifies which images to flash to which partitions.

 # Image Assembly Config

 The image assembly config specifies the **contents** of the Fuchsia system that is put
 into the images.

 ```json5
 {
   // The set of packages included when flashing or updating a device, and should
   // not be removed by the garbage collector.
   base: [ "path/to/package_manifest.json" ],

   // The set of packages included when flashing or updating a device, but can be
   // removed by the garbage collector.
   cache: [ "path/to/package_manifest.json" ],

   // The set of system-critical packages included in the "System Image"
   // (i.e. base package).
   system: [ "path/to/package_manifest.json" ],

   kernel: {

     // Path on host to the kernel ZBI.
     path: "path/to/kernel.zbi",

     // The arguments to pass to the kernel on boot.
     args: [ "arg1", "arg2" ],

     // The minimum clock time.
     // See https://fuchsia.dev/fuchsia-src/concepts/time/utc/behavior for more information.
     // The backstop is called out as a required argument to prevent mistakes.
     clock_backstop: 10,
   },

   // Arguments available in the boot service for userspace programs.
   boot_args: [ "arg1", "arg2" ],

   // Files to put in BootFS.
   bootfs_files: [
     {
       source: "path/to/file/on/host",
       destination: "path/to/file/in/bootfs",
     }
   ],

   // Packages to put in BootFS.
   bootfs_packages: [
     "path/to/package_manifest.json",
     "path/to/package_manifest.json",
   ]
 }
 ```

 # Images Config

 The images config specifies **which images** to generate and how.

 ```json5
 {
   images: [
     <image>,
     <image>,
   ],
 }
 ```

 `<image>` specifies a single image to generate, and has the following format.

 ```json5
 {
   type: "<type>",
   name: "<name>",
   <type-specific-parameters>,
 }
 ```

 `<type>` can be one of: zbi, vbmeta, or fvm.

 ## zbi type

 ```json5
 {
   type: "zbi",

   // The name to give the file: fuchsia.zbi
   name: "fuchsia",

   // The compression format for the ZBI.
   compression: "zstd.max",

   // An optional script to post-process the ZBI.
   // This is often used to prepare the ZBI for the
   postprocessing_script: <post-processing-script>,
 }
 ```

 `<post-processing-script>` has the following format.

 ```json5
 {
   // The path to the script on host.
   // This script _musts_ take the following arguments:
   //   -z <path to ZBI>
   //   -o <output path>
   //   -B <build directory, relative to script's source directory>
   path: "path/to/script/on/host.sh",

   // Additional arguments to pass to the script after the above arguments.
   args: [ "arg1", "arg2" ],
 }
 ```

 ## VBMeta Type

 ```json5
 {
   type: "vbmeta",

   // The name to give the file: fuchsia.vbmeta
   name: "fuchsia",

   // Path on host to the key for signing VBMeta.
   key: "path/to/key/on/host",

   // Path on host to the key metadata to add to the VBMeta.
   key_metadata: "path/to/key/metadata/on/host",

   // Optional descriptors to add to the VBMeta image.
   additional_descriptors: [
     <descriptor>,
     <descriptor>,
   ],
 }
 ```

 ### VBMeta Descriptor

 `<descriptor>` has the following format.

 ```json5
 {
   // Name of the partition.
   name: "mypart",

   // Size of the partition in bytes.
   size: 12345,

   // Custom VBMeta flags to add.
   flags: 1,

   // Minimum AVB version to add.
   min_avb_version: "1.1",
 }
 ```

 ## FVM Type

 ```json5
 {
   type: "fvm",

   // The name to give the file: fvm.blk
   name: "fvm",

   // The size of a slice within the FVM.
   slice_size: 0,

   // The list of filesystems to generate that can be added to the outputs.
   filesystems: [
     <filesystem>,
     <filesystem>,
   ],

   // The FVM images to generate.
   outputs: [
     <fvm-output>,
     <fvm-output>,
   ],
 }
 ```

 ### Filesystem

 `<filesystem>` can be one of the following.

 ```json5
 {
   type: "blobfs",

   // The name of the volume in the FVM.
   name: "blob",

   // Optionally compress the volume file.
   compress: true,

   // Optional deprecated layout.
   layout: "deprecated-padded",

   // Reserve |minimum_data_bytes| and |minimum_inodes| in the FVM, and ensure
   // that the final reserved size does not exceed |maximum_bytes|.
   maximum_bytes: 0,
   minimum_data_bytes: 0,
   minimum_inodes: 0,
 }
 ```

 ```json5
 {
   type: "minfs",

   // The name of the volume in the FVM.
   name: "data",

   // Reserve |minimum_data_bytes| and |minimum_inodes| in the FVM, and ensure
   // that the final reserved size does not exceed |maximum_bytes|.
   maximum_bytes: 0,
   minimum_data_byts: 0,
   minimum_inodes: 0,
 }
 ```

 ```json5
 {
   type: "empty-minfs",

   // The name of the volume in the FVM.
   name: "data_empty",
 }
 ```

 ```json5
 {
   type: "reserved",

   // The name of the volume in the FVM.
   name: "internal",

   // The number of slices to reserve.
   slices: 1000,
 }
 ```

 ### FVM Output

 `<fvm-output>` can be one of the following.

 ```json5
 {
   type: "standard",

   // The name to give the file: fvm.blk.
   name: "fvm",

   // The filesystems to include in the FVM.
   filesystems: [
     "blob",
     "data",
     "internal",
   ],

   // Whether to compress the FVM.
   compress: true,

   // Shrink the FVM to fit exactly the contents.
   resize_image_file_to_fit: true,

   // After the optional resize, truncate the file to this length.
   truncate_to_length: 0,
 }
 ```

 ```json5
 {
   type: "sparse",

   // The name to give the file: fvm.sparse.blk.
   name: "fvm.sparse",

   // The filesystems to include in the FVM.
   filesystems: [
     "blob",
     "data",
     "internal",
   ],

   // Whether to compress the FVM.
   compress: true,

   // The maximum size the FVM can expand to at runtime.
   // This sets the amount of slice metadata to allocate during construction,
   // which cannot be modified at runtime.
   max_disk_size: 0,
 }
 ```

 ```json5
 {
   type: "nand",

   // The name to give the file: fvm.nand.blk.
   name: "fvm.nand",

   // The filesystems to include in the FVM.
   filesystems: [
     "blob",
     "data",
     "internal",
   ],

   // Whether to compress the FVM.
   compress: true,

   // The maximum size the FVM can expand to at runtime.
   // This sets the amount of slice metadata to allocate during construction,
   // which cannot be modified at runtime.
   max_disk_size: 0,
   block_count: 0,
   oob_size: 0,
   page_size: 0,
   pages_per_block: 0,
 }
 ```

 ## Example

 ```json5
 {
   images: [
     {
       type: "zbi",
       name: "fuchsia",
     },
     {
       type: "vbmeta",
       name: "fuchsia",
       key: "path/to/key",
       key_metadata: "path/to/key/metadata",
     },
     {
       type: "fvm",
       name: "fvm",
       slice_size: 0,
       filesystems: [
         {
           type: "blobfs",
           name: "blob",
           compress: true,
           maximum_bytes: 65536,
           minimum_data_bytes: 0,
           minimum_inodes: 4096,
         },
         {
           type: "minfs",
           name: "data",
           maximum_bytes: 65536,
           minimum_data_bytes: 0,
           minimum_inodes: 4096,
         },
       ],
       outputs: [
         {
           type: "standard",
           name: "fvm",
           filesystems: [
             "blob",
             "data",
           ],
         },
         {
           type: "sparse",
           name: "fvm.sparse",
           filesystems: [
             "blob",
             "data",
           ],
           compress: true,
           max_disk_size: 65536,
         },
       ],
     },
   ],
 }
 ```

 # Images Manifest

 ```json5
 [
   <image>,
   <image>,
 ]
 ```

 ## Image

 `<image>` has the following format.

 ```json5
 {
   name: "zircon-a",
   path: "path/on/host/to/image",
   type: <image-type>,
 }
 ```

 `<image-type>` must be one of: zbi, vbmeta, base-package, blob, storage-full,
 storage-sparse, storage-sparse-blob, or fvm.fastboot.

 ## Example

 ```json5
 [
   {
     name: "zircon-a",
     path: "path/to/fuchsia.zbi",
     type: "zbi",
   },
   {
     name: "zircon-a",
     path: "path/to/fuchsia.vbmeta",
     type: "vbmeta",
   }
 ]
 ```

 # Partitions Config

 ```json5
 {

   // The list of bootloader partitions that are not slot-specific.
   booloader_partitions: [
     <bootloader-partition>,
     <bootloader-partition>,
   ],

   // The list of non-bootloader partitions that are slot-specific.
   partitions: [
     <partition>,
     <partition>,
   ],
 }
 ```

 ## Bootloader Partition

 `<bootloader-partition>` has the following format.

 ```json5
 {
   // The name of the partition known to fastboot.
   name: "bootloader",

   // The firmware type provided to the update system.
   // See documentation here:
   //   https://fuchsia.dev/fuchsia-src/concepts/packages/update_pkg
   type: "tpl",

   // Path on host to the image.
   image: "path/on/host/to/image",
 }
 ```

 ## Partition

 `<partition>` has the following format.

 ```json5
 {
   // The name of the partition known to fastboot.
   name: "zircon_a",
   type: "<partition-type>",
   slot: "<partition-slot>",
 }
 ```

 `<partition-type>` can be one of: `ZBI`, `VBMeta`, `FVM`. `<partition-slot>` can be
 one of: `A`, `B`, `R`.

 ## Example

 ```json5
 {
   booloader_partitions: [
     {
       name: "bootloader",
       type: "tpl",
       image: "path/to/bootloader.tpl",
     },
   ],
   partitions: [
     {
       name: "zircon_a",
       type: "ZBI",
       slot: "A",
     },
     {
       name: "vbmeta_a",
       type: "VBMeta",
       slot: "A",
     },
     {
       name: "zircon_b",
       type: "ZBI",
       slot: "B",
     },
     {
       name: "vbmeta_b",
       type: "VBMeta",
       slot: "B",
     },
     {
       name: "fvm",
       type: "FVM",
       slot: "A",
     },
   ],
 }
 ```
	# FFX Plugin for Product and Image Assembly

	TODO: Document Product Assembly

	[Image Assembly RFC-0072](/docs/contribute/governance/rfcs/0072_standalone_image_assembly_tool.md).

	Image Assembly is responsible for taking prebuilt artifacts and generating
	images that can be used to update or flash a Fuchsia device. The FFX plugin has
	three subcommands: [`create-system`](#create_system),
	[`create-update`](#create_update), and
	[`create-flash-manifest`](#create_flash_manifest).

	![Command Flow](images/commands.png)

	# create-system

	Create a Fuchsia system that minimally includes a ZBI, and optionally a VBMeta
	and FVM images.

	```bash
	ffx assembly create-system \
	--image-assembly-config image_assembly_config.json \
	--images images_config.json \
	--outdir <output-directory>
	```

	## Arguments

	\| input \| format \| description \|
	\| --- \| --- \| --- \|
	\| `--image-assembly-config` \| [Image Assembly Config](#image-assembly-config) \| Contents of the Fuchsia system that are put into the images. \|
	\| `--images` \| [Images Config](#images-config) \| Which images to generate and how. \|
	\| `--outdir` \| path \| Directory to write outputs. \|
	\| `--gendir` \| path \| (optional; default=outdir) Directory to write intermediate files. \|
	\| `--base-package-name` \| string \| (optional; default="system_image") Name to give the Base Package. This is currently only used by OTA tests to allow publishing muliple base packages to the same amber repository without naming collisions. \|
	\| `--mode` \| [Modes](#modes) \| (optional; default="standard") Where to put the packages. \|

	## Modes

	\| mode \| description \|
	\| --- \| --- \|
	\| `standard` \| Packages are placed in a blobfs in a FVM that is flashed to a separate partition. \|
	\| `fvm_in_zbi` \| Packages are placed in a blobfs in a FVM that is embedded into the ZBI as a ramdisk. \|
	\| `bootfs_only` \| Packages are placed into BootFS. \|

	## Outputs

	\| output \| format \| description \|
	\| --- \| --- \| --- \|
	\| `packages.json` \| [Package Manifest](/docs/concepts/packages/update_pkg.md) \| List of packages in the system. \|
	\| `images.json` \| [Images Manifest](#images-manifest) \| List of images generated. \|
	\| `fuchsia.zbi` \| \| Fuchsia Zircon Boot Image (ZBI). \|
	\| `fuchsia.vbmeta` \| \| Fuchsia Verified Boot Metadata (VBMeta). \|
	\| `fvm.blk` \| \| Fuchsia Volume Manager (FVM). \|

	# create-update

	Create an update package for updating a running Fuchsia system.

	```bash
	ffx assembly create-update \
	--packages packages.json \
	--partitions partitions.json \
	--system-a images.json \
	--system-r recovery_images.jso \
	--board-name "board" \
	--version-file version.txt \
	--epoch 0 \
	--outdir <output-directory>
	```

	## Arguments

	input \| format \| description
	----------------------- \| --------------------------------------------------------- \| -----------
	`--packages` \| [Package Manifest](/docs/concepts/packages/update_pkg.md) \| List of packages in the system.
	`--partitions` \| [Partitions Config](#partitions-config) \| Where in the partition table the images are put.
	`--system-[a,b,r]` \| [Images Manifest](#images-manifest) \| The system to place in the slot.
	`--board-name` \| string \| The name of the board. Fuchsia will reject an Update Package with a different board name.
	`--version-file` \| path of file containing `a.b.c.d`, where each digit is u32 \| The file containing the version of the Fuchsia system.
	`--epoch` \| int \| The backstop OTA version. Fuchsia will reject updates with a lower epoch.
	`--outdir` \| path \| Directory to write outputs.
	`--gendir` \| path \| (optional; default=outdir) Directory to write intermediate files.
	`--update-package-name` \| string \| (optional; default="update") Name to give the Update Package. This is currently only used by OTA tests to allow publishing multiple update packages to the same amber repository without naming collisions.

	## Outputs

	output \| format \| description
	------------ \| ----------------------------------------------- \| ---------------
	`update.far` \| [Format](/docs/concepts/packages/update_pkg.md) \| Update package.

	# create-flash-manifest

	Create a manifest file that describes how to flash images onto a Fuchsia device.

	```bash
	ffx assembly create-flash-manifest \
	--partitions partitions.json \
	--system-a images.json \
	--system-b images.json \
	--system-r recovery_images.json \
	--outdir <output-directory>
	```

	## Arguments

	\| input \| format \| description \|
	\| --- \| --- \| --- \|
	\| `--partitions` \| [Partitions Config](#partitions-config) \| Where in the partition table the images are put. \|
	\| `--system-[a,b,r]` \| [Images Manifest](#images-manifest) \| The system to place in the slot. \|
	\| `--outdir` \| path \| Directory to write outputs. \|

	## Output

	output \| format \| description
	------------ \| -------------------------------------------------------------------------------------------- \| -----------
	`flash.json` \| [RFC-0100](https://fuchsia.dev/fuchsia-src/contribute/governance/rfcs/0100_product_metadata) \| Flash manifest that specifies which images to flash to which partitions.

	# Image Assembly Config

	The image assembly config specifies the contents of the Fuchsia system that is put
	into the images.

	```json5
	{
	// The set of packages included when flashing or updating a device, and should
	// not be removed by the garbage collector.
	base: [ "path/to/package_manifest.json" ],

	// The set of packages included when flashing or updating a device, but can be
	// removed by the garbage collector.
	cache: [ "path/to/package_manifest.json" ],

	// The set of system-critical packages included in the "System Image"
	// (i.e. base package).
	system: [ "path/to/package_manifest.json" ],

	kernel: {

	// Path on host to the kernel ZBI.
	path: "path/to/kernel.zbi",

	// The arguments to pass to the kernel on boot.
	args: [ "arg1", "arg2" ],

	// The minimum clock time.
	// See https://fuchsia.dev/fuchsia-src/concepts/time/utc/behavior for more information.
	// The backstop is called out as a required argument to prevent mistakes.
	clock_backstop: 10,
	},

	// Arguments available in the boot service for userspace programs.
	boot_args: [ "arg1", "arg2" ],

	// Files to put in BootFS.
	bootfs_files: [
	{
	source: "path/to/file/on/host",
	destination: "path/to/file/in/bootfs",
	}
	],

	// Packages to put in BootFS.
	bootfs_packages: [
	"path/to/package_manifest.json",
	"path/to/package_manifest.json",
	]
	}
	```

	# Images Config

	The images config specifies which images to generate and how.

	```json5
	{
	images: [
	<image>,
	<image>,
	],
	}
	```

	`<image>` specifies a single image to generate, and has the following format.

	```json5
	{
	type: "<type>",
	name: "<name>",
	<type-specific-parameters>,
	}
	```

	`<type>` can be one of: zbi, vbmeta, or fvm.

	## zbi type

	```json5
	{
	type: "zbi",

	// The name to give the file: fuchsia.zbi
	name: "fuchsia",

	// The compression format for the ZBI.
	compression: "zstd.max",

	// An optional script to post-process the ZBI.
	// This is often used to prepare the ZBI for the
	postprocessing_script: <post-processing-script>,
	}
	```

	`<post-processing-script>` has the following format.

	```json5
	{
	// The path to the script on host.
	// This script _musts_ take the following arguments:
	// -z <path to ZBI>
	// -o <output path>
	// -B <build directory, relative to script's source directory>
	path: "path/to/script/on/host.sh",

	// Additional arguments to pass to the script after the above arguments.
	args: [ "arg1", "arg2" ],
	}
	```

	## VBMeta Type

	```json5
	{
	type: "vbmeta",

	// The name to give the file: fuchsia.vbmeta
	name: "fuchsia",

	// Path on host to the key for signing VBMeta.
	key: "path/to/key/on/host",

	// Path on host to the key metadata to add to the VBMeta.
	key_metadata: "path/to/key/metadata/on/host",

	// Optional descriptors to add to the VBMeta image.
	additional_descriptors: [
	<descriptor>,
	<descriptor>,
	],
	}
	```

	### VBMeta Descriptor

	`<descriptor>` has the following format.

	```json5
	{
	// Name of the partition.
	name: "mypart",

	// Size of the partition in bytes.
	size: 12345,

	// Custom VBMeta flags to add.
	flags: 1,

	// Minimum AVB version to add.
	min_avb_version: "1.1",
	}
	```

	## FVM Type

	```json5
	{
	type: "fvm",

	// The name to give the file: fvm.blk
	name: "fvm",

	// The size of a slice within the FVM.
	slice_size: 0,

	// The list of filesystems to generate that can be added to the outputs.
	filesystems: [
	<filesystem>,
	<filesystem>,
	],

	// The FVM images to generate.
	outputs: [
	<fvm-output>,
	<fvm-output>,
	],
	}
	```

	### Filesystem

	`<filesystem>` can be one of the following.

	```json5
	{
	type: "blobfs",

	// The name of the volume in the FVM.
	name: "blob",

	// Optionally compress the volume file.
	compress: true,

	// Optional deprecated layout.
	layout: "deprecated-padded",

	// Reserve \|minimum_data_bytes\| and \|minimum_inodes\| in the FVM, and ensure
	// that the final reserved size does not exceed \|maximum_bytes\|.
	maximum_bytes: 0,
	minimum_data_bytes: 0,
	minimum_inodes: 0,
	}
	```

	```json5
	{
	type: "minfs",

	// The name of the volume in the FVM.
	name: "data",

	// Reserve \|minimum_data_bytes\| and \|minimum_inodes\| in the FVM, and ensure
	// that the final reserved size does not exceed \|maximum_bytes\|.
	maximum_bytes: 0,
	minimum_data_byts: 0,
	minimum_inodes: 0,
	}
	```

	```json5
	{
	type: "empty-minfs",

	// The name of the volume in the FVM.
	name: "data_empty",
	}
	```

	```json5
	{
	type: "reserved",

	// The name of the volume in the FVM.
	name: "internal",

	// The number of slices to reserve.
	slices: 1000,
	}
	```

	### FVM Output

	`<fvm-output>` can be one of the following.

	```json5
	{
	type: "standard",

	// The name to give the file: fvm.blk.
	name: "fvm",

	// The filesystems to include in the FVM.
	filesystems: [
	"blob",
	"data",
	"internal",
	],

	// Whether to compress the FVM.
	compress: true,

	// Shrink the FVM to fit exactly the contents.
	resize_image_file_to_fit: true,

	// After the optional resize, truncate the file to this length.
	truncate_to_length: 0,
	}
	```

	```json5
	{
	type: "sparse",

	// The name to give the file: fvm.sparse.blk.
	name: "fvm.sparse",

	// The filesystems to include in the FVM.
	filesystems: [
	"blob",
	"data",
	"internal",
	],

	// Whether to compress the FVM.
	compress: true,

	// The maximum size the FVM can expand to at runtime.
	// This sets the amount of slice metadata to allocate during construction,
	// which cannot be modified at runtime.
	max_disk_size: 0,
	}
	```

	```json5
	{
	type: "nand",

	// The name to give the file: fvm.nand.blk.
	name: "fvm.nand",

	// The filesystems to include in the FVM.
	filesystems: [
	"blob",
	"data",
	"internal",
	],

	// Whether to compress the FVM.
	compress: true,

	// The maximum size the FVM can expand to at runtime.
	// This sets the amount of slice metadata to allocate during construction,
	// which cannot be modified at runtime.
	max_disk_size: 0,
	block_count: 0,
	oob_size: 0,
	page_size: 0,
	pages_per_block: 0,
	}
	```

	## Example

	```json5
	{
	images: [
	{
	type: "zbi",
	name: "fuchsia",
	},
	{
	type: "vbmeta",
	name: "fuchsia",
	key: "path/to/key",
	key_metadata: "path/to/key/metadata",
	},
	{
	type: "fvm",
	name: "fvm",
	slice_size: 0,
	filesystems: [
	{
	type: "blobfs",
	name: "blob",
	compress: true,
	maximum_bytes: 65536,
	minimum_data_bytes: 0,
	minimum_inodes: 4096,
	},
	{
	type: "minfs",
	name: "data",
	maximum_bytes: 65536,
	minimum_data_bytes: 0,
	minimum_inodes: 4096,
	},
	],
	outputs: [
	{
	type: "standard",
	name: "fvm",
	filesystems: [
	"blob",
	"data",
	],
	},
	{
	type: "sparse",
	name: "fvm.sparse",
	filesystems: [
	"blob",
	"data",
	],
	compress: true,
	max_disk_size: 65536,
	},
	],
	},
	],
	}
	```

	# Images Manifest

	```json5
	[
	<image>,
	<image>,
	]
	```

	## Image

	`<image>` has the following format.

	```json5
	{
	name: "zircon-a",
	path: "path/on/host/to/image",
	type: <image-type>,
	}
	```

	`<image-type>` must be one of: zbi, vbmeta, base-package, blob, storage-full,
	storage-sparse, storage-sparse-blob, or fvm.fastboot.

	## Example

	```json5
	[
	{
	name: "zircon-a",
	path: "path/to/fuchsia.zbi",
	type: "zbi",
	},
	{
	name: "zircon-a",
	path: "path/to/fuchsia.vbmeta",
	type: "vbmeta",
	}
	]
	```

	# Partitions Config

	```json5
	{

	// The list of bootloader partitions that are not slot-specific.
	booloader_partitions: [
	<bootloader-partition>,
	<bootloader-partition>,
	],

	// The list of non-bootloader partitions that are slot-specific.
	partitions: [
	<partition>,
	<partition>,
	],
	}
	```

	## Bootloader Partition

	`<bootloader-partition>` has the following format.

	```json5
	{
	// The name of the partition known to fastboot.
	name: "bootloader",

	// The firmware type provided to the update system.
	// See documentation here:
	// https://fuchsia.dev/fuchsia-src/concepts/packages/update_pkg
	type: "tpl",

	// Path on host to the image.
	image: "path/on/host/to/image",
	}
	```

	## Partition

	`<partition>` has the following format.

	```json5
	{
	// The name of the partition known to fastboot.
	name: "zircon_a",
	type: "<partition-type>",
	slot: "<partition-slot>",
	}
	```

	`<partition-type>` can be one of: `ZBI`, `VBMeta`, `FVM`. `<partition-slot>` can be
	one of: `A`, `B`, `R`.

	## Example

	```json5
	{
	booloader_partitions: [
	{
	name: "bootloader",
	type: "tpl",
	image: "path/to/bootloader.tpl",
	},
	],
	partitions: [
	{
	name: "zircon_a",
	type: "ZBI",
	slot: "A",
	},
	{
	name: "vbmeta_a",
	type: "VBMeta",
	slot: "A",
	},
	{
	name: "zircon_b",
	type: "ZBI",
	slot: "B",
	},
	{
	name: "vbmeta_b",
	type: "VBMeta",
	slot: "B",
	},
	{
	name: "fvm",
	type: "FVM",
	slot: "A",
	},
	],
	}
	```