examples/target-disk-mode: Update README
@@ -7,8 +7,50 @@ What's this?
This is a system that allows you to present the internal storage of a device
over the USB connection using Linux USB gadget mode.
+
+How to use
+----------
+
+This will differ depending on the device.
+
+The main thing to know is that you need to build a *bootable* image for your
+device.
+
+This will have different implications depending on the device.
+
+
+### U-Boot based systems
+
+(E.g. `pine64-pinephone`)
+
+```
+ $ nix-build examples/target-disk-mode/ --argstr device pine64-pinephone -A build.default
+ $ file -L result
+result: DOS/MBR boot sector; partition 1 : ID=0xee, start-CHS (0x0,0,2), end-CHS (0x3ff,255,63), startsector 1, 319555 sectors, extended partition table (last)
+```
+
+The disk image produced can be flashed to a bootable medium (e.g. an SD card).
+
+
+### Android-based systems
+
+(None)
+
+> **NOTE**: Adding this feature for android-based systems, at the time being,
+> is **dangerous**. Overwriting parts of the disk could lead to **really
+> actually bricked** devices.
+
+```
+ $ nix-build examples/target-disk-mode/ --argstr device ____ -A build.android-bootimg
+ $ file -L result
+result: Android bootimg, kernel (0x10008000), ramdisk (0x11000000), page size: 2048, cmdline (...)
+```
+
+This boot image can be ran using `fastboot boot`, if the device supports it, or
+flashed to the recovery or the boot partition.
+
* * *
-With that said, while the project differs enough in implementation, I want
-to acknowledge the obvious inspiration taken from the [JumpDrive](https://github.com/dreemurrs-embedded/Jumpdrive)
+While the project differs in implementation, I want to acknowledge the
+inspiration taken from the [JumpDrive](https://github.com/dreemurrs-embedded/Jumpdrive)
project.
