How to boot from SPI Flash

Both VIMs can boot from different boot media like eMMC, SD Card and USB Disk, but different with VIM1, as VIM2 specs with a 2MB SPI Flash, so VIM2 can also boot from SPI Flash. And here is an instructions how to boot VIM2 from the SPI Flash.


Build SPI Flash supported U-Boot

As the boot media are different, to support SPI Flash, we have to enable following first, which is located on uboot/board/khadas/configs/kvim2.h:

diff --git a/board/khadas/configs/kvim2.h b/board/khadas/configs/kvim2.h
index c7a8fd6..d1556ba 100644
--- a/board/khadas/configs/kvim2.h
+++ b/board/khadas/configs/kvim2.h
@@ -386,7 +386,7 @@
-//#define CONFIG_SPI_BOOT 1
+#define CONFIG_SPI_BOOT 1

After modification, build again:

$ cd uboot
$ make distclean
$ make CROSS_COMPILE=aarch64-linux-gnu- kvim2_defconfig
$ make CROSS_COMPILE=aarch64-linux-gnu- 

Gerneration file for SPI Flash:


Download U-Boot into SPI Flash

To continue the guidance, you have to follow up Load Images with U-Boot via TFTP Instructions do the setup first.

1) Load u-boot.bin into memory via tftp

kvim2# tftp 12000000 u-boot.bin

2) Initiate the SPI Flash

kvim2# sf probe

3) Erase SPI Flash

kvim2# sf erase 0 200000

Above command will earse all the whole SPI Flash, the offset is 0 and the size is 200000.

4) Download U-Boot into SPI Flash

kvim2# sf write 12000000 0 200000

5) Set the default boot meidia as SPI Flash

kvim2# kbi bootmode w spi 

The default boot media is eMMC, and here we use kbi to change it to SPI Flash. kbi means Khadas Bootloader Instrucionts, you can refer more KBI instrucions at TBD.

If you wanna check the boot media, you can run:

kvim2# kbi bootmode r
bootmode: spi

6) Check it
To check it, you have to power off the VIM2 first, and power on again:

AddrBus test pass!
Load fip header from SPI, src: 0x0000c000, des: 0x01400000, size: 0x00004000
New fip structure!
Load bl30 from SPI, src: 0x00010000, des: 0x01100000, size: 0x0000d600
Load bl31 from SPI, src: 0x00020000, des: 0x05100000, size: 0x00018400

The Load fip header from SPI printing it says that VIM2 is boot from the SPI Flash.


Hello! Can you tell if this will ever be native? Because the native way of Khadas Vim2 we can cause brick in some update that writes the Uboot wrong. I would like Khadas to have a more micro-like behavior when it comes to image installation.

I didn’t understand what you mean? Can you describe it in detail?