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Version: 029-rc4

Device platform

A platform file in kas/platforms/ declares the set of Yocto/OE layers required for a family of devices. Platform files are shared across multiple machine configurations — for example, freescale.yaml is included by both nxp.yaml and toradex.yaml.

Before creating a new platform file, check whether a suitable one already exists: kas/platforms/. Existing platforms include freescale.yaml, toradex.yaml, raspberrypi.yaml, rockchip.yaml, sunxi.yaml, ti.yaml, and variscite.yaml.

Worked Example: the Toradex Platform​

The layer already ships this content as kas/platforms/toradex.yaml — a good template for a new platform file. Here is how it is put together.

1 — Identify the Vendor Layers​

Consult the vendor's documentation or BSP manifest to find the required Yocto layers. For Toradex NXP boards the required layers are:

  • meta-toradex-bsp-common
  • meta-toradex-nxp
  • meta-freescale, meta-freescale-distro, meta-freescale-3rdparty (already in freescale.yaml)

2 — Declare the Layers in the Platform YAML​

kas/platforms/toradex.yaml uses header.includes to reuse the existing freescale.yaml rather than duplicating the Freescale layer definitions:

header:
  version: 16
  includes:
    - kas/platforms/freescale.yaml   # reuse existing Freescale layers

repos:
  meta-toradex-bsp-common:
    path: layers/meta-toradex-bsp-common
    url: "https://git.toradex.com/meta-toradex-bsp-common.git"
    branch: scarthgap-7.x.y

  meta-toradex-nxp:
    path: layers/meta-toradex-nxp
    url: "https://git.toradex.com/meta-toradex-nxp.git"
    branch: scarthgap-7.x.y

Branches must match the Yocto release you are targeting (scarthgap or kirkstone).

3 — Add Platform-Level BitBake Variables (if needed)​

Use local_conf_header to inject variables into build/conf/local.conf for all machines that include this platform. For example, the raspberrypi.yaml platform enables U-Boot and UART:

local_conf_header:
  platform-raspberrypi: |
    LICENSE_FLAGS_ACCEPTED += "synaptics-killswitch"
    RPI_USE_U_BOOT = "1"
    ENABLE_UART = "1"

Add a local_conf_header block to your platform file if your vendor BSP requires default configuration flags.

Platform File Structure​

KeyPurpose
header.versionKAS format version (use 16 for current releases)
header.includesOther platform YAML files to include (for layer reuse)
reposGit repositories for the vendor BSP layers
local_conf_headerVariables to append to build/conf/local.conf
bblayers_conf_headerLines to append to build/conf/bblayers.conf — e.g. nxp.yaml uses it to BBMASK vendor recipes

Once the platform file exists, create a machine file to target a specific board.