Galaxy S3

<fc #ff0000>TWRP+Magisk is recommended!</fc>, but here's the old tutorial. Doesn't matter really ;)

1. extract cache.img and recovery.img into the AutoRoot directory.
2. run heimdall-frontend as root.
3. Click the Utilities tab.
4. Disconnect the USB cable, if attached.
5. Power off your Samsung device. To insure that it is completely shutdown, you can remove the battery and reinsert it.
6. Connect the USB cable from the phone to the computer.
7. In Heimdall press the Detect button.
8. You need to save the PIT (Partition Information Table) file from the device.
   1. In the Download PIT section of the Utilities tab
   2. USB -3 error means that you did not run heimdall-frontend as root.
9. Once you have a PIT file, you can click the Flash tab.
10. select the PIT you downloaded
11. Add a partition, and ignore the partition display.
    1. add Recovery (with recovery.img) and Cache (with cache.img)
12. Enable No Reboot option, click Start
13. After flash, while holding down the Power button, unplug the USB cable. Keep holding down the Power button, and press the vol+ until the Galaxy S3 boots into Recovery.
14. CF-Auto-Root installs the necessary files, and the SuperSU application.

Load module mtdblock:

It emulates block devices over MTD devices.