Apply DualBoot with DualBoot Kernel Patcher

This guide will help you build a boot image with uefi/android dualboot feature.

Prepare

• An android device.
• Download UEFI FD file from Github Action(You may need to login to download artifacts) or Release Page of uefi repository.
• Magiskboot for your environment, there are prebuilt binaries on github.
• DualBoot kernel patcher binary and shellcode binaries for your devices from release page or action page.

:::Notice All these steps can be done on your android device. :::

Steps

Assume you have done the following steps on your android device.

1. Root your device with magisk.
2. Downloaded and installed termux.
3. Installed root-repo and tsu in termux with apt.

• Get Android Boot Image.

  • The boot image usually can be found at /dev/block/by-name/boot or /dev/block/by-name/boot_a (or _b).
  • Open your termux, and copy the boot image out for future use.

  tsu                             # get root shell
  mkdir /sdcard/dualboot/         # create a folder to put files.
  cp /dev/block/by-name/boot /sdcard/dualboot/boot.img  # copy to our folder and rename to boot.img. If your device has ab slot, please add _a or _b suffix.

• Unpack it with magiskboot.

  • If your device was rooted by magisk, there should be an magiskboot binary at /data/adb/magisk/magiskboot
  • By the way you can press the tab button in termux to automatically fill path, instead of typing the characters one by one.
  • Do Unpack

  cd /sdcard/dualboot/            # change working directory to our folder.
  /data/adb/magisk/magiskboot unpack boot.img # unpack

  • You will get something like this:

  /sdcard/dualboot# magiskboot unpack boot.img
  Parsing boot image: [boot.img]
  HEADER_VER      [1]
  KERNEL_SZ       [41576325]
  RAMDISK_SZ      [927736]
  SECOND_SZ       [0]
  RECOV_DTBO_SZ   [0]
  OS_VERSION      [9.0.0]
  OS_PATCH_LEVEL  [2021-05]
  PAGESIZE        [4096]
  NAME            []
  CMDLINE         [console=ttyMSM0,115200n8 earlycon=msm_geni_serial,0xa90000 androidboot.hardware=qcom androidboot.console=ttyMSM0 androidboot.memcg=1 lpm_levels.sleep_disabled=1 video=vfb:640x400,bpp=32,memsize=3072000 msm_rtb.filter=0x237 service_locator.enable=1 swiotlb=2048 firmware_class.path=/vendor/firmware_mnt/image loop.max_part=7 androidboot.usbcontroller=a600000.dwc3 buildvariant=user]
  CHECKSUM        [e73518a6e1edf3062d9cebd3203a51069ef2f424000000000000000000000000]
  KERNEL_DTB_SZ   [3972965]
  KERNEL_FMT      [raw]
  RAMDISK_FMT     [raw]
  /sdcard/dualboot# ls
  boot  kernel  kernel_dtb  ramdisk.cpio

• Apply patch with dualboot kernel patcher.

  • Assume the patcher and shellcodes and config you downloaded above was saved at /sdcard/Download/
  • Unpack these zips:

  unzip /sdcard/Download/