Introduction

The Toradex Easy Installer makes use of JSON files and, if required, the files can be edited using a plain text editor. However, care must be taken not to violate the JSON specification.

To make sure the JSON file is still well-formatted an online JSON validator can be useful (e.g. jsonlint.com).

Image Format

This chapter lists the available properties and how they get interpreted by the Toradex Easy Installer.

Each Easy Installer compatible image is described in a JSON image file. Toradex provides images with a proper JSON image file. Yet, depending on the use case you might need to alter the JSON image file e.g. to add an additional partition. The easiest way is to take an existing image.json file and alter it accordingly.

The JSON consists of a single root dictionary with several mandatory properties (*: Mandatory). An image can define its configuration format. Newer configurations support more features but require a newer Toradex Easy Installer version.

Note: *: Mandatory property

Block Devices

Each blockdev entry has a name and either partition or content node or both. In case of using a partition table and (raw) content, the Toradex Easy Installer will first create the partition table and then write the content according to the specification.

Make sure that the partition table created and the data written do not conflict!

Note: *: Mandatory property

Partition

If partitions are specified, the installer will create an MBR/DOS-style partition table. Currently, only primary partitions are supported. All partitions will be aligned to 4-megabyte boundaries (8192 blocks).

A partition specification knows the following properties:

MTD Devices

Each blockdev entry has a name and either a content, ubivolumes or winceimage node.

Note: *: Mandatory property

UBI volume

Note: *: Mandatory property

WinCE image

The WinCE image section allows writing a WinCE image in the sparse file format to raw NAND (uses the utility flash-wince).

Note: *: Mandatory property

Common

Content

For block devices, content can either be raw data (dd-style) or a file system. For MTD device, content can only be raw data (uses Linux nandwrite command) and for UBI volume, content can either be raw data (uses Linux ubiupdatevol command) or ubifs.

Raw Files

Example

This is a typical example derived from a standard Linux image.json file: It creates the usual two partition layout, a FAT partition for the Kernel/Device Trees and an ext3 partition for the root file system. An additional third partition has been added to create a location for user data.

The filename or filelist property can be used to pre-install user/application data.

{
    "config_format": 1, 
    "autoinstall": true, 
    "name": "Toradex Embedded Linux BSP using LXDE desktop", 
    "description": "Toradex Embedded Linux BSP using LXDE desktop.", 
    "version": "V2.6.1", 
    "release_date": "2016-10-13", 
    "prepare_script": "prepare.sh", 
    "wrapup_script": "wrapup.sh", 
    "marketing": "marketing.tar", 
    "icon": "toradexlinux.png", 
    "supported_product_ids": [
        "0027", 
        "0028", 
        "0029", 
        "0035"
    ], 
    "blockdevs": [
        {
            "name": "mmcblk0", 
            "partitions": [
                {
                    "partition_size_nominal": 16, 
                    "want_maximised": false,
                    "content": {
                        "uncompressed_size": 4, 
                        "filesystem_type": "FAT", 
                        "filename": "Apalis_iMX6_LinuxImage.bootfs.tar.xz", 
                        "mkfs_options": "", 
                        "label": "BOOT"
                    }
                }, 
                {
                    "partition_size_nominal": 512, 
                    "want_maximised": false,
                    "content": {
                        "uncompressed_size": 300, 
                        "filesystem_type": "ext3", 
                        "filename": "Apalis_iMX6_LinuxImage.rootfs.tar.xz", 
                        "mkfs_options": "", 
                        "label": "RFS"
                    }
                }, 
                {
                    "partition_size_nominal": 512, 
                    "want_maximised": true,
                    "content": {
                        "filesystem_type": "ext3",
                        "label": "DATA"
                    }
                }
            ]
        }, 
        {
            "name": "mmcblk0boot0"
            "content": {
                "filesystem_type": "raw",
                "rawfiles": [
                    {
                        "filename": "SPL",
                        "dd_options": "seek=2"
                    },
                    {
                        "filename": "u-boot.imx",
                        "dd_options": "seek=138"
                    }
                ]
            },
        }
    ]
}

Image List Format

Images loaded from an HTTP server need an index file that points to the individual images. The file name is typically image_list.json, but it can be anything.

A local HTTP server needs such an image list file to point to the individual images.

This example points to two images, which are located in the directories Apalis_iMX6_LinuxImage_V2.6.2 and Apalis_iMX6_LinuxConsoleImage_V2.6.2 relative to the location of this index file:

{
  "config_format": 1,
  "images": [
    "Apalis_iMX6_LinuxImage_V2.6.2/image.json",
    "Apalis_iMX6_LinuxConsoleImage_V2.6.2/image.json"
  ]
}

Configuration Format

The Toradex Easy Installer configuration file allows adding additional HTTP image sources.

The configuration file needs to be named tezi_config.json and located on the root of any partition on a supported external storage media (SD card or USB flash drive). This allows extending the search locations for image lists beyond the pre-configured Toradex servers, e.g. to distribute images in a local network or over RNDIS.

{
  "config_format": 1,
  "image_lists": [
     "http://192.168.10.2:8008/image_list.json"
  ]
}