There is no-doubt a simpler/better way, but this worked well for me just the other day for dual-boot ATV...
would anyone be able to provide us (me) with a simplified version of the os x install?
1. Patchstick your ATV so you can ssh to it
2. Remove a total of eight screws from under the rubber foot, carefully open the ATV and unplug the 2.5inch P-ATA hard drive, removing it
3. Connect the ATV's HD to a firewire or USB board, such that you can connect it to your Mac. I dismantled an existing firewire 2.5inch case and swapped the ATV's drive into it. Two volumes Media and OSBoot should mount
4. Do a full install of the "common" (ie: retail disc or one suitable for all macs) universal 10.4.8 or higher, onto the Media volume. Maybe a model-specific one would work too, haven't tried it.
5. Update it to 10.4.11 with all updates
6. Swap in the replacement mach_kernel and boot.efi
7. Remove the NVIDIA kernel exts (5 of them, they are at System/Library/Extensions/NVD* on the Media volume)
8. Put the drive back into the ATV and turn it on. It will boot ATV OS.
9. SSH into the ATV and run the following bless command: sudo bless --folder /Volumes/Media/System/Library/CoreServices --file /Volumes/Media/System/Library/CoreServices/boot.efi --setBoot --nextonly
10. Restart and you should have Mac OS X
Can i do the install with an msi wind running os x?
Things work with varying degrees of success. Some things that don't work can be coaxed into working, typically by mucking around with kernel extensions.
What works, what doesn't work?
Interestingly, Mac OS X on the ATV appears not to be able to play HD h.264 content with any sort of decent frame rate, even when ATV OS can play the same movie file perfectly (for instance, the HD movie that the ATV OS plays at startup). Even a custom Cocoa app I wrote, when deployed onto ATV OS can play h.264 content fine, but the same app runs very poorly on the same ATV running Mac OS X. Clearly, QuickTime on ATV OS is doing something tricky to account for the fact that the CPU doesn't cut it (or, ATV OS is sufficiently less resource hungry than full Mac OS X that it can play them). I've heard a rumour that there is a hardware h.264 decoder in the ATV, which ATV QuickTime presumably knows how to use.
Yes, as above. If you do the bless with --nextonly it will give you mac os x for that one boot, then you can just restart to go back to ATV OS. If you do not use --nextonly it will be a permanent Mac OS X box until you bless it back to the OSBoot drive from Terminal.
Can i dual boot atvos and os x?
Sound does not work. Might be a kernel issue, not sure it can be easily worked around. Wired ethernet doesn't work either, but you can make it work by copying a kernel extension. Airport works fine without any mucking around.
also does sound work? wifi?
All universal versions of Tiger afaik, which included some 10.4.7 discs but all 10.4.8-10.4.11 versions.
and is semthex's kernal compatable with all versions of os x?!