Serial NOR Boot

IoT Yocto now provides reference support for booting from Serial NOR Flash used to store the bootloader. Others such as kernel and rootfs are stored in the storage device. The Genio EVK does not have on-board Serial NOR Flash, so this section is based on reworked EVK boards for Serial NOR boot demonstration.

Build Packages

Please assign the MACHINE config variable to build the packages for the Genio EVK board:

Genio 510-EVKGenio 700-EVKGenio 1200-EVK

The bootloader will boot from Serial NOR Flash and then boot the kernel and rootfs from eMMC.

export MACHINE=genio-510-evk-norboot
bitbake rity-demo-image

Serial NOR Flash Layout

We store the bootloader defined as firmware category in Serial NOR Flash. The following table describes the layout scheme for the Genio EVK board using Serial NOR Flash.

Serial NOR Flash Layout on Genio EVK Boards

Category	Partition Label	Size	Partition Image	Remark
Firmware	nor_env	4MB	u-boot-env.bin	Runtime generated by genio-flash tool based on u-boot-initial-env plain text file and additional configurations
Firmware	nor_bootassets	4MB	bootassets.img	Static bootloader data such as boot logos
Firmware	nor_misc	1MB	N/A	Support A/B firmware update feature
Firmware	nor_dramk	512KB	N/A	One-time programming for per-board DRAM calibration data
Firmware	nor_firmware_b	4MB	N/A	Preserved for future use
Firmware	nor_firmware_a	4MB	N/A	Preserved for future use
Firmware	nor_fip_b	4MB	fip.bin	The content in?bootloaders and?bootloaders_b?should be the same initially
Firmware	nor_fip_a	4MB	fip.bin	Containing fip.bin, which consists of BL3* loaders (BL31, BL32, BL33)
Firmware	nor_bl2	4MB	bl2.img	2nd stage bootloader based on Trusted-Firmware-A

Layout Configurations

IoT Yocto provides a simple solution for adjusting the size and layout of Serial NOR Flash. Users can find the layout definition in the download agent (lk) and U-Boot for customization. The following example describes the nor_bl2 layout definition for Genio 1200-EVK :

• target.h in the download agent (lk) for Genio 1200-EVK :

#define NOR_PARTITIONS_INDEX0 "nor_bl2"

• genio_1200_evk_ufs_qspi_defconfig in the U-Boot for Genio 1200-EVK:

CONFIG_MTDPARTS_DEFAULT="mtdparts=nor0:4m(nor_bl2),..."

In this example, users can find the 4MB region size and the offset of nor_bl2 in the layout definition for Serial NOR Flash. In addition, users can also customize the layout definition according to their product requirements.

Note

Please make sure the layout definition of the download agent (lk) and U-Boot are the same, otherwise the system will fail to boot.