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VIM4 OS Boot Priority
VIM4 is capable of boot-up from: eMMC, 'TF Card, SPI-Flash
We talking there only about 1st stage SOC boot,
next second stage OS loading possible for any other devices like USB storage's,
NVMe etc … and depends from u-boot configurations
===== Default boot priority =====
- TF-Card always have 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
```shell
kvim4# kbi bootmode w emmc
```
Change boot priority to: TF-Card ⇒ SPI-Flash ⇒ eMMC
```shell
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 =====
```sh
i2cset -f -y 6 0x18 0x20 1 # setup default eMMC boot-mode
```
```sh
i2cset -f -y 6 0x18 0x20 0 # setup SPI-flash boot-mode
```
==== Hot apply setting changes via mcu reboot ====
```sh
i2cset -f -y 6 0x18 0x91 1
```
===== OOWOW boot special shortcut =====
Hold FUNCTION and short press RESET'' to force boot OOWOW service from SPI-flash, and skip other boot sources
TF-card slot must be empty