Enabling Secondary Media


Admins should already have read about Secondary media.

Device configuration

  • Not all test devices can support secondary media deployments in LAVA.
  • Additional hardware is typically required and configuration details of this specific hardware need to be added to the device dictionary to be available to test writers.
  • The use of operating system installers and/or the deployment of full system images to a DUT can substantially increase the administrative burden of that device. Administrators can choose to not enable this support.
  • Secondary media configuration can be complex and hard to deploy as admins need to understand how one specific device fits into the range of options which are available to cover other devices. Some level of familiarity with Developing using device-type templates will be required to be able to follow the logic.

Identifying secondary media

A deployment to secondary media must be done by a running operating system, not by the bootloader. To allow this, the device configuration may need extra restrictions.

To work reliably, media devices must be consistently, uniquely identifiable. Some test devices may have multiple SATA disks; on others, different types of media device (USB storage, SATA, SD) may even show up using the same style of device name (e.g. sda). Ordering of these devices is not guaranteed on each boot of the system, particularly when using different configurations and different kernels. To make such a setup work in all cases, the device_type needs to declare the flag UUID-required: True for each relevant interface. Using cubietruck as an example:

media:  # two USB slots, one SATA connector
    UUID-required: True
    UUID-required: False

Secondary media configuration

When configuring and using secondary media, there are six sets of parameters used. In each case, this section only deals with the generic or root parameter and each deployment method uses a specific variant to cope with the requirements of the possible bootloaders. Admins need to obtain the various pieces of information required for the parameters from a running device before starting to write the configuration for secondary media on the same device. To obtain the correct values, it may be necessary to take the device offline, connect to it over serial and interact with the bootloader directly. Once this data has been obtained, the specific configuration for a deployment method can involve setting other values beyond the core six.


Should a device fail or the secondary media on a device need to be replaced, the secondary media identifiers will need to be updated before the new hardware can work with the device.

The presence of the uuid for the particular deployment will enable all the other options used by secondary media using the same deployment method. Each deployment method has a dedicated uuid so that the template can provide the correct information to the dispatcher. Typically, one device will have one uuid for one deployment method, so the other deployment methods will be disabled.

Three deployment methods are currently supported. sata, sd and usb. The examples in this section are not intended to provide a complete overview of all deployment methods but to provide context for why particular values need to be obtained from the device before secondary media configuration can begin.

Admins will typically also need to use device tag if more than one device of this device-type exists in the instance.

The first two parameters must be configured by admins in the device dictionary. They define the storage device that will be used for the secondary media deployment, and for safety test writers should not be able to override these settings.

The last three parameters, boot_part, root_uuid and root_part can be used by the test writer in their job submission, depending on how the deployed image has been built:

  1. The uuid parameter in the device configuration

    This is the ID of the storage device as it appears to the kernel running the deploy action. This can be found by looking in /dev/disk/by-id/ on a booted system.

    For example, a SATA drive which appears as /dev/disk/by-id/ata-ST500DM002-1BD142_S2AKYFSN would define sata_uuid and have an entry in the device dictionary of:

    {% set sata_uuid = 'ata-ST500DM002-1BD142_S2AKYFSN' %}


    Currently, only one UUID (and hence only one storage device) is supported for each of the available interfaces (SATA, USB and SD) for each DUT.

  2. The device_id parameter in the device configuration

    This is the ID of the device as it appears to the bootloader when reading deployed files into memory. This can be found by interrupting the bootloader and listing the filesystem contents on the specified interface. The device_id is closely related to the interface name used in the bootloader to specify the name of the interface which the bootloader will use to access the device_id. With some bootloaders, only the interface value is required.

    For example, when using GRUB, the first detected SATA drive would be (hd0), so the device dictionary only needs:

    {% set sata_interface = 'hd0' %}


    The parentheses are omitted here, as GRUB also needs to know the partition number - boot_part within the syntax (hd0,1). The final string is a combination of device and test job configuration because it is the submitted image which determines where the kernel image has been installed.

  3. The label by which test writers can select the secondary media. Admins need to consider how best to create the label. The string should relate to the kind of media which is supported - USB stick or SATA drive etc. However, the label itself should not be entirely specific to the hardware on one specific machine. Often, DUTs will be deployed with similar hardware of the same overall brand or model and this provides a good label. For example, if all devices of the same device-type have Seagate Barracuda 500GB SATA drives as secondary media, then the sata_label could be usefully set as:

    {% set sata_label = 'ST500DM002' %}

    If all devices of another device-type have SanDisk Cruzer Blade USB sticks as secondary media, the usb_label could be usefully set as:

    {% set usb_label = 'SanDiskCruzerBlade' %}

    Remember that unless the uuid is set, this label has no effect. If there are some devices of the same device-type without SATA drives, the device dictionary for those devices simply omits the sata_uuid. Use a device tag on the devices with secondary media to allow test writers to submit to one of the supported devices.

  4. The boot_part can be specified in the job submission if the default in the device type template is not correct for the deployed image. This is the number of the partition within the deployed image which will contain files for the bootloader to use too boot (kernel, initramfs, etc.). Files in this partition will be accessed directly through the bootloader, not via any mount point specified inside the image.

  5. The root_uuid can be specified in the job submission if the default in the device type template is not correct for the deployed image. This is the ID of the partition to specify as root on the kernel command line of the deployed kernel when booting the kernel inside the image. This must be specified if the device has UUID-required set to True.

  6. The root_part can be specified in the job submission if the default in the device type template is not correct for the deployed image. This is the partition number inside the deployed image where the rootfs lives. root_part cannot be used with root_uuid - to do so causes a JobError.

Media settings are configured per test device, based on the capability of the device type. An individual test device of a specified type may have exactly one of the available slots populated on any one interface. These individual devices would need UUID-required: False for that interface. e.g. A panda has two USB host slots. For each panda, if both slots are occupied, specify UUID-required: True in the device configuration. If only one is occupied, specify UUID-required: False.

If none are occupied, avoid enabling usb_uuid in the device dictionary to disable the usb interface section in the configuration for that one device.

List each specific storage device attached to that interface using a human-usable string, e.g. a SanDisk Ultra usb stick with a UUID of usb-SanDisk_Ultra_20060775320F43006019-0:0 could simply be called SanDisk_Ultra. Jobs will specify this label in order to look up the actual UUID, allowing physical media to be replaced with an equivalent device without needing to change the job submission data.

The device configuration should always include the UUID for all media on each supported interface, even if UUID-required is False. The UUID is the recommended way to specify the media, even when not strictly required. Record the symlink name (without the path) for the top level device in /dev/disk/by-id/ for the media concerned, i.e. the symlink pointing at ../sda not the symlink(s) pointing at individual partitions. The UUID should be quoted to ensure that the YAML can be parsed correctly. Also include the device_id which is the bootloader view of the same device on this interface.

device_type: cubietruck
 connect: telnet localhost 6000
  usb:  # bootloader interface name
    UUID-required: True  # cubie1 is pretending to have two usb media attached
      uuid: "usb-SanDisk_Ultra_20060775320F43006019-0:0"  # /dev/disk/by-id/
      device_id: 0  # the bootloader device id for this media on the 'usb' interface

There is no reasonable way for the device configuration to specify the device node directly, as this may change from job to job depending on the configuration of the deployed system.

Using Grub with SATA secondary media

Device dictionary

{% set sata_uuid = 'ata-ST500DM002-1BD142_S2AKYFSN' %}
{% set sata_label = 'ST500DM002' %}
  • sata_uuid enables secondary media on a SATA interface for this device and is used to locate the device node as it appears to the kernel of the first deployment stage to allow LAVA to write the secondary image.
  • sata_label will need to be specified in the test job to identify the SATA device to use for secondary media.

In this case, boot_part, device_id, grub_interface and uboot_interface are left as default values from the device-type template.

A more complete device dictionary would look like:

{% set sata_label = 'ST500DM002' %}
{% set sata_uuid = 'ata-ST500DM002-1BD142_S2AKYFSN' %}
{% set device_id = 0 %}
{% set sata_interface = 'hd0' %}
{% set boot_part = 1 %}

Device template example



The duplication of uboot_interface and grub_interface is yet to be fixed in the dispatcher code. Currently, the same interface gets set for each for this specific item and one entry is simply unused at runtime.

{% if sata_uuid or sd_uuid or usb_uuid %}
{% if sata_uuid %}
     UUID-required: {{ uuid_required|default(True) }}
     {{ sata_label|default('ST160LM003') }}:
       uuid: {{ sata_uuid }}
       device_id: {{ sata_id|default(0) }}
       uboot_interface: {{ sata_interface|default('scsi') }}
       grub_interface: {{ sata_interface|default('hd0') }}
       boot_part: {{ boot_part|default(1) }}
{% endif %} #  sata_uuid
{% if sd_uuid %}
     {{ sd_label }}:
       uuid: {{ sd_uuid }}
       device_id: {{ sd_device_id }}  # the bootloader device id for this media on the 'sd' interface
{% endif %} #  sd_uuid
{% if usb_uuid %}
     {{ usb_label|default('SanDisk_Ultra') }}:
       uuid: {{ usb_uuid }}  # /dev/disk/by-id/
       device_id: {{ usb_device_id }}  # the bootloader device id for this media on the 'usb' interface
{% endif %} # usb_uuid
{% else %}
{%- endif %} # sata_uuid_sd_uuid_usb_uuid

Dispatcher configuration

The device dictionary is combined with the template to create the actual configuration sent to the worker:

'parameters': {
    'media': {
        'sata': {
            'ST500DM002': {
                'boot_part': 1,
                'device_id': 0,
                'grub_interface': 'hd0',
                'uboot_interface': 'scsi',
                'uuid': 'ata-ST500DM002-1BD142_S2AKYFSN'
            'UUID-required': True

Grub SATA Test Job submission

A test writer constructs a deployment action, after booting their chosen primary deployment, selecting the relevant device_id and deployment method (to: sata).

- deploy:
   namespace: satadeploy
   # secondary media - use the first deploy to get to a system which can deploy the next
     minutes: 30
   to: sata
   os: debian
   device: ST500DM002 # needs to be exposed in the device-specific UI

Using UBoot with USB secondary media

Device dictionary

{% set usb_label = 'SanDiskCruzerBlade' %}
{% set usb_uuid = 'usb-SanDisk_Cruzer_Blade_20060266531DA442AD42-0:0' %}
{% set usb_device_id = 0 %}

Dispatcher configuration

'parameters': {
  "media": {
    "usb": {
      "SanDiskCruzerBlade": {
        "uuid": "usb-SanDisk_Cruzer_Blade_20060266531DA442AD42-0:0",
        "device_id": 0
      "UUID-required": true

USB UBoot Test Job submission

A test writer constructs a deployment action, after booting their chosen primary deployment, selecting the relevant device_id and deployment method (to: sata).

- deploy:
   namespace: android
     minutes: 40
   to: usb
   os: android
       url: http://releases.linaro.org/members/arm/android/juno/16.09/juno.img.bz2
       compression: bz2
   device: SanDiskCruzerBlade