Fastboot

Note

Despite its name, it is NOT the Android Fastboot, though it can actually boot Android bootimgs. Clearly it’s U-Boot forked around 2014, and removed all copyright notices.

Vendor Fastboot support booting from uImage or Android bootimg (uImage + initrd).

Please be aware that, Vendor Fastboot depends on Hisi Reg file, which contains initial values for critical registers, such as DDR training. The reg file must also match your board for proper boot in addition to SoC type.

Boot sequence

If USB_BOOT is pulled down, it will try to read two files on u-disk:
- bootargs.bin: U-Boot env file, sector size: 0x10000
- recovery.img: Android bootimg or uImage
Otherwise, go to next step.
Read Android bootimg or uImage from eMMC or NAND storage.

If Secure Boot is enabled, only Android bootimg will be considered.

Prepare uImage / Android bootimg

Prepare uImage:

sudo apt install u-boot-tools

cat zImage dtb > zImage-dtb
mkimage -A arm -O linux -T kernel -C none -a 0x2000000 -e 0x2000000 -n Linux-$VER -d zImage-dtb uImage

Prepare Android bootimg, using uImage:

sudo apt install mkbootimg

# without ramdisk
mkbootimg --kernel uImage --base 0 --kernel_offset 0x3e08000 -o bootimg
# with ramdisk
mkbootimg --kernel uImage --ramdisk ramdisk.cpio.xz --base 0 --kernel_offset 0x3e08000 --ramdisk_offset 0x4e00000 -o recovery.img

TODO: work out offset meaning

Prepare `bootargs.bin`

Use U-Boot fw-utils to prepare bootargs.bin.

sudo apt install libubootenv-tool

Example fw_env.config:

bootargs.bin 0 0x10000 0x10000

# read bootargs
fw_printenv -c fw_env.config
# write bootargs
fw_setenv -c fw_env.config $key $value

Console Output

See Boards.