How to Patch boot.img with Magisk on Linux

Here’s a step-by-step guide to patching your Android boot.img with Magisk on a Linux system.

🔹 Prerequisites

1. Unlocked Bootloader – Required to flash a modified boot.img.
2. ADB & Fastboot – Install on Linux:
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   sudo apt update && sudo apt install adb fastboot -y  # Debian/Ubuntu
   sudo dnf install android-tools       # Fedora
   sudo pacman -S android-tools         # Arch

3. Magisk APK – Download the latest Magisk ZIP (rename .apk to .zip if needed).
4. Stock boot.img – Extract from your device’s firmware or dump it via:
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   adb reboot bootloader
   fastboot flash boot boot.img  # (if you already have a backup)

   or dump it:
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   fastboot boot boot.img  # (temporary boot, useful for testing)
   fastboot flash boot boot.img  # (permanent flash)

   To dump your current boot.img:
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   fastboot flash boot
   fastboot reboot
   adb pull /dev/block/bootdevice/by-name/boot boot.img

   (Path varies by device; check /proc/emmc or use lsblk in adb shell.)

🔹 Method 1: Patch via Magisk App (Recommended)

(Requires an Android device to run the Magisk app.)

1. Transfer boot.img to your phone:
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   adb push boot.img /sdcard/Download/

2. Open Magisk App → Install → Select and Patch a File → Choose boot.img.
3. Magisk will generate magisk_patched-<random>.img in /sdcard/Download/.
4. Pull the patched file back to Linux:
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   adb pull /sdcard/Download/magisk_patched-*.img

5. Flash the patched boot.img:
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   adb reboot bootloader
   fastboot flash boot magisk_patched-*.img
   fastboot reboot

🔹 Method 2: Manual Patch on Linux (Advanced)

(For users who want to patch entirely on Linux without an Android device.)

Step 1: Extract magiskboot from Magisk ZIP

Magisk includes a tool called magiskboot that can patch boot.img directly.

1. Download Magisk ZIP (e.g., Magisk-v26.4.zip).
2. Extract magiskboot:
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   unzip Magisk-*.zip -d magisk
   chmod +x magisk/magiskboot

Step 2: Patch boot.img

./magisk/magiskboot unpack boot.img

This extracts:

• kernel
• ramdisk.cpio
• cmdline
• board (device tree, if present)

2. Add Magisk to the ramdisk:

   • Extract the ramdisk.cpio:
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     mkdir ramdisk && cd ramdisk
     cpio -i -F ../ramdisk.cpio

   • Copy Magisk files (from the Magisk ZIP) into the ramdisk:
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     cp -r ../magisk/common/* .
     cp -r ../magisk/overlay.d/* .

   • Repack the ramdisk:
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     find . | cpio -o -H newc -R 0:0 | gzip > ../ramdisk_new.cpio.gz
     cd ..

3. Repack boot.img:

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   ./magisk/magiskboot repack boot.img --ramdisk ramdisk_new.cpio.gz

   (If your device uses a separate dtb or recovery_dtbo, include them with --dtb or --recovery_dtbo.)

4. Flash the new boot.img:

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   fastboot flash boot new-boot.img
   fastboot reboot

🔹 Method 3: Using magiskboot Directly (Simplest CLI Method)

If your boot.img is not a dtbo-split image (most modern devices), you can patch it in one command:

./magisk/magiskboot hexpatch boot.img

This automatically injects Magisk into the ramdisk if possible.

Then flash:

fastboot flash boot boot.img
fastboot reboot

(If this fails, use Method 2 for manual patching.)

⚠️ Troubleshooting

🔥 For Android 12+ (Dynamic Partitions)

Some devices (e.g., Pixel, Samsung) use init_boot.img instead of boot.img.

1. Dump init_boot.img:
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   fastboot flash init_boot
   fastboot reboot
   adb pull /dev/block/bootdevice/by-name/init_boot init_boot.img

2. Patch it (same as boot.img):
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   ./magisk/magiskboot hexpatch init_boot.img
   fastboot flash init_boot init_boot.img

📌 Final Notes

✅ Always backup your original boot.img before flashing. ✅ Disable vbmeta verification if bootloop occurs:

fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img

✅ Check your device’s XDA forum for specific instructions (e.g., Samsung, OnePlus, Pixel).