Building a Minimal Yocto BSP from Scratch: meta-layer to Boot

Why a Custom BSP Layer

Yocto's BSP layers abstract hardware-specific configurations from the distro. A well-structured BSP layer means switching from prototype to production board by changing one line.

Layer Structure

meta-myboard/
├── conf/machine/myboard.conf
├── recipes-bsp/u-boot/u-boot_%.bbappend
├── recipes-kernel/linux/linux-myboard.bb
└── recipes-core/myapp/myapp_1.0.bb

Machine Configuration

require conf/machine/include/arm/armv8a/tune-cortexa53.inc
KERNEL_IMAGETYPE = "Image"
KERNEL_DEVICETREE = "myboard.dtb"
PREFERRED_PROVIDER_virtual/kernel = "linux-myboard"
SERIAL_CONSOLES = "115200;ttyS0"

Device Tree

Override the upstream device tree with board-specific nodes for your SPI flash, custom GPIOs, and UART configuration. Include your SoC's base dtsi file and add your peripherals.

Systemd Service Integration

inherit systemd
SYSTEMD_SERVICE:${PN} = "myapp.service"
SYSTEMD_AUTO_ENABLE = "enable"