Merge pull request #11 from UrkiMimi/ipod_touch_2g

Document how to generate the filesystem-it2g-readonly.img

Author: devos50

README.md

@@ -3,14 +3,50 @@
 This README contains the instructions on how to generate the NAND image for the iPod Touch 2G that can be read by [QEMU-iOS](https://github.com/devos50/qemu-ios).
 For this, you must put the `filesystem-it2g-readonly.img` file of the filesystem that will be included in the NAND image in the root of this repository.
 
-First, compile the binary with the following command:
+
+## Compiling Instructions
+To compile, run this command to compile the binary:
 
 ```
 gcc generate_nand.c -o generate_nand
 ```
 
+## Converting the filesystem into an image
+Converting the filesystem to an image is somewhat simple. You first need to convert the filesystem read-only with hdiutil:
+
+```
+hdiutil convert -format UDRO filesystem-it2g-writable.dmg -o filesystem-it2g-readonly.dmg
+```
+
+Before converting `filesystem-it2g-readonly.dmg` you will need to find what partition you need to convert. You can find this out easily by using dmg2img to list the disk partitions.
+
+```
+username@Macbook-Air qemu-ios-generate-nand %dmg2img -l filesystem-it2g-readonly.dmg
+
+dmg2img v1.6.7 (c) vu1tur ([email protected])
+
+filesystem-it2g-readonly.dmg --> (partition list)
+
+partition 0: Driver Descriptor Map (DDM : 0)
+partition 1:  (Apple_Free : 1)
+partition 2: Apple (Apple_partition_map : 2)
+partition 3: Macintosh (Apple_Driver_ATAPI : 3)
+partition 4:  (Apple_Free : 4)
+partition 5: Mac_OS_X (Apple_HFSX : 5)
+partition 6:  (Apple_Free : 6)
+```
+
+For me, partition 5 is the one I need to convert. Now convert the image with the partition number like so:
+
+```
+dmg2img -p 5 filesystem-it2g-readonly.dmg
+```
+
+# Generating the NAND Image
+
+
 Before generating the NAND image, make sure to remove any prior NAND data by running `rm -rf nand`.
-Then, generate your NAND image by running the compiled binary:
+Using the filesystem image we generated from earlier, run this command from the binary you compiled.
 
 ```
 ./generate_nand