參考資訊：
https://knulli.org/guides/h700-firmware-extract/
https://github.com/anestisb/android-unpackbootimg
步驟如下：
$ cd
$ wget https://github.com/steward-fu/website/releases/download/rg28xx/RG28XX-V1.0.4-EN16GB-240511.7z
$ 7za x RG28XX-V1.0.4-EN16GB-240511.7z
$ sudo fdisk -l RG28XX-V1.0.4-EN16GB-240511.IMG
Disk RG28XX-V1.0.4-EN16GB-240511.IMG: 14.48 GiB, 15552479232 bytes, 30375936 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: AB6F3888-569A-4926-9668-80941DCB40BC
Device Start End Sectors Size Type
RG28XX-V1.0.4-EN16GB-240511.IMG1 73728 8880127 8806400 4.2G Microsoft basic data
RG28XX-V1.0.4-EN16GB-240511.IMG2 8880128 8945663 65536 32M Microsoft basic data
RG28XX-V1.0.4-EN16GB-240511.IMG3 8945664 8978431 32768 16M Microsoft basic data
RG28XX-V1.0.4-EN16GB-240511.IMG4 8978432 9109503 131072 64M Microsoft basic data
RG28XX-V1.0.4-EN16GB-240511.IMG5 9109504 25886719 16777216 8G Microsoft basic data
RG28XX-V1.0.4-EN16GB-240511.IMG6 25886720 30373887 4487168 2.1G Microsoft basic data
$ dd if=RG28XX-V1.0.4-EN16GB-240511.IMG of=env.img bs=512 skip=8945664 count=32768
$ strings env.img > env.txt
$ cat env.txt | head
earlyprintk=sunxi-uart,0x05000000
initcall_debug=0
console=ttyS0,115200
nand_root=/dev/nand0p4
mmc_root=/dev/mmcblk0p5
init=/init
loglevel=4
selinux=0
cma=64M
mac=
$ mkenvimage -s 0x1000000 -o env.img env.txt