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Core Configuration Files

Kconfig Entry Points​

make kernel_menuconfig   # Linux kernel
make menuconfig          # Tina/OpenWrt packages
mrtos menuconfig         # RISC-V MCU RTOS

Linux kernel menuconfig

Tina menuconfig

RTOS menuconfig

Common configuration files:

device/config/chips/v821/configs/aitoy/linux-5.4-ansc/bsp_defconfig
openwrt/target/v821/v821-aitoy/defconfig
rtos/lichee/rtos/projects/v821_e907/aitoy/defconfig

Device Trees​

bsp/configs/linux-5.4-ansc/sun300iw1p1.dtsi
    Common SoC resources

device/config/chips/v821/configs/aitoy/linux-5.4-ansc/board.dts
    Board resources; normally the preferred file for product changes

device/config/chips/v821/configs/aitoy/uboot-board.dts
    U-Boot board display, storage, and related settings

The board board.dts overrides matching properties from the common dtsi. Avoid product-specific edits in the common dtsi because they affect other boards.

Partition Tables​

  • SPI NOR: sys_partition_nor.fex
  • SPI NAND/eMMC/SD: sys_partition.fex
[partition]
name         = rootfs
size         = 20480
downloadfile = "rootfs.fex"
user_type    = 0x8000

Partition sizes must obey the erase-block alignment of the selected medium. SPI NOR commonly uses 64KB alignment. SPI NAND alignment must account for physical erase blocks and UBI logical erase blocks.

env.cfg and sys_config.fex​

device/config/chips/v821/configs/default/env.cfg
device/config/chips/v821/configs/aitoy/env.cfg
device/config/chips/v821/configs/aitoy/sys_config.fex

env.cfg controls boot delay, console parameters, log levels, and related values; fast-boot boards may bypass it. sys_config.fex is mainly consumed by BOOT0 and takes precedence over conflicting U-Boot device-tree settings.

BOOT0 UART example:

[uart_para]
uart_debug_port = 0
uart_debug_tx = port:PD22<3><1><default><default>
uart_debug_rx = port:PD23<3><1><default><default>

[platform]
debug_mode = 8

debug_mode=0 disables BOOT0 logging; 8 enables full logging.

Root Filesystem​

SquashFS is the default read-only root filesystem. EROFS can be selected instead:

make menuconfig
# CONFIG_TARGET_ROOTFS_EROFS=y
# disable TARGET_ROOTFS_SQUASHFS

make kernel_menuconfig
# CONFIG_EROFS_FS=y

Writable data is normally provided by a rootfs_data overlay: JFFS2 for SPI NOR and commonly ext4 for eMMC. Do not continuously write large files to /mnt/extsd when no SD card is mounted, because the path may fall back to the small overlay partition.