Turbo's AppleTV Hacks @ 0xfeedbeef.com

This document will describe how to boot from USB on a "virgin" Apple TV. It assumes that you, for the most part, know what you're doing.
Thanks go to mk500 and Jordan (phoem) for testing.
Creating a disk to boot from USB
 Notes: There are 2 key ingredients for booting from USB on the AppleTV:
  Some helpful tools to know: dd, hdiutil, gpt, disktool, asr

Partition your disk
 Purpose: Set up your disk for booting the AppleTV
 Notes: Use Disk Utility to partition your disk using "GUID Partition Table"
  Create 1 partition, type HFS+ Journaled
  If you're using a 5G iPod, this part is already done, skip to loading your OS
  If you're working with a disk image (.dmg) you'll need to use the command line gpt tool to create your partitions
Load your operating system
 Purpose: You're not going to get very far without installing an operating system
 Notes: Loading of OS X and kernel is beyond the scope of this document. See semthex's howto, or use asr.
  Once you change the GUID partition type, you cannot use the Mac OSX Installer to install on that volume.
  You will need to use the "boot.efi" from an original AppleTV
  You will also need a modified kernel, such as this one from semthex with his awesome SSE3 emulator.

  Be sure to delete System/Library/Extensions.mkext and System/Library/Extensions.kextcache if they exist on your new drive.
Patch AppleFileSystemDriver
 Purpose: AppleFileSystemDriver.kext must be patched in order for the kernel to recognize the special partition type
 Notes: This is obviously already done in the original AppleTV kernel.
  If you're using semthex's kernel with stock OS X Extensions, you'll need to patch this.
  Add the following section to the file System/Library/Extensions/AppleFileSystemDriver.kext/Contents/Info.plist in the IOPropertyMatch array:

<key>media-match</key> <dict> <key>IOPropertyMatch</key> <array> <dict> <key>Content Hint</key> <string>5265636F-7665-11AA-AA11-00306543ECAC</string> <key>Leaf</key> <true/> </dict> <dict> <key>Content Hint</key> <string>Apple_Recovery</string> <key>Leaf</key> <true/> </dict> <dict> <key>Content Hint</key> <string>48465300-0000-11AA-AA11-00306543ECAC</string> <key>Leaf</key> <true/> </dict>

Change Partition Type
 Purpose: Now that everything is configured, change the partition type so the AppleTV will recognise it
 Notes: Once you do this, the disk (or iPod) will no longer auto mount on your workstation.
  Change it back, or mount it with mount_hfs at the command line
 Notes: This is non-destructive only if you do it correctly!
  Make sure you record all the information output by "gpt show" for your device.

  Load and patch your operating system before changing the partition type.

gpt -r show /dev/diskX start size index contents 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 6 40 8192 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B 8232 520155 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC 528387 520156 3 GPT part - 48465300-0000-11AA-AA11-00306543ECAC 1048543 32 Sec GPT table 1048575 1 Sec GPT header disktool -u diskX gpt remove -i 2 /dev/diskX disktool -u diskX gpt add -b 8232 -s 520155 -i 2 -t "5265636F-7665-11AA-AA11-00306543ECAC" /dev/diskX

Plug it in and boot!
 Notes: If you've done the above correctly, simply plug it into your AppleTV and boot! You're done!
Create a disk image instead of using a real disk
 Purpose: The AppleTV requires a specially configured GPT (GUID) partition table
 Notes: Begin by creating and mounting your disk image. This example is a 2GB disk image

dd if=/dev/zero of=outfile.dmg bs=1024k count=2048 2048+0 records in 2048+0 records out 2147483648 bytes transferred hdiutil attach -nomount outfile.dmg /dev/diskX

  The image will appear as a regular block device node (/dev/diskX) and you can treat it as a disk
  Now use 'gpt' to create your partitions. The first partition is probably unneeded now, but might be useful in the future.
  This example will create a GPT partition table with a 4MB EFI system partition, 1 2044MB "Recovery" partition
  Adjust your sizes accordingly. Note the partition types here, because if you use the "Recovery" type, your partition will not mount.

gpt create /dev/diskX gpt add -b 40 -s 8192 -i 1 -t "C12A7328-F81F-11D2-BA4B-00A0C93EC93B" /dev/diskX gpt add -b 8232 -s 4194304 -i 2 -t "48465300-0000-11AA-AA11-00306543ECAC" /dev/diskX

  If you did it correctly, it should look something like this:

gpt -r show /dev/diskX start size index contents 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 6 40 8192 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B 8232 4194304 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

Format your partitions
 Purpose: Create the filesystems to hold your OS X files
 Notes: Obviously, skip this step if you used your iPod or other pre-configured disk

newfs_msdos /dev/rdiskXs1 newfs_hfs -v "Recovery" /dev/diskXs2

Modified 2007-12-14 14:06:35
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