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products:sbc:vim4:development:boot-sequence
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VIM4 OS Boot Priority
VIM4 is capable of booting from the following devices: eMMC, TF Card, SPI Flash
We talking there only about 1st stage SOC boot, next second stage os loading possible for any other diveices like USB storages, NVME etc … and depends from u-boot configurations
Default boot priority
- TF-Card TF-card will always take the highest priority.
- eMMC
- SPI-Flash
U-boot shell usage
We can swap the boot priority of the eMMC and SPI Flash via the KBI(Khadas Boot Instructions) from u-boot shell
Change boot priority to: TF-Card ⇒ eMMC ⇒ SPI-Flash
kvim4# kbi bootmode w emmc
Change boot priority to: TF-Card ⇒ SPI-Flash ⇒ eMMC
kvim4# kbi bootmode w spi
for apply setting for next boot, need reboot device by RESET button or re-plug power cable or power-off device or reboot via mcu
Linux command-line usage
i2cset -f -y 6 0x18 0x20 1 # setup default eMMC boot-mode
i2cset -f -y 6 0x18 0x20 0 # setup SPI-flash boot-mode
Hot apply setting changes via mcu reboot
i2cset -f -y 6 0x18 0x91 1
Last modified: 2022/07/26 02:59 by hyphop