Netboot and iPXE

[jpwise]

Hopefully noone minds some double posting. I'd like to collate information relating to my attempts to boot iPXE 'over' the network on Apple iMac/Macbook hardware.

NOTE: This is not the same as putting it on a CD and booting it using CD.

As I understand based on my research to date, when you boot to CD using iPXE (or windows/linux) etc, the Mac is booting in Bios Compatibility mode - Refer http://en.wikipedia.org/wiki/Apple–Intel...re#Booting.

Firstly that rules out booting a standard ipxe.usb compiled binary image from usb, and limits you to using a CD interface.

Ideally I would like to bootstrap the Mac into iPXE using the Mac Netboot environment without using usb (see above post). This is limited to compatible EFI binaries only however. If a suitable Binary can be built and confirmed OK using a USB stick then the same binary can generally also be run using Netboot.

Grub2-EFI i have successfully compiled and booted from usb stick by placing the compiled efi binary in the correct location on the usb stick (see Ubuntu UEFIBooting page). As above the resulting binary could also be served and executed over Netboot aswell.

Grub-EFI & Grub2-EFI however do NOT support linux16 to execute 16 bit binaries. Various websites show menu entries chaining ipxe.lkrn using grub and the linux16 command, however on grub efi versions the command doens't exist, so can't do it that way. It also errors if you try the normal 'linux' command.

So far my attempts to compile an ipxe EFI file haven't resulted in a functionary EFI binary insofar as grub or the Mac were concerned at any rate. Also further to that after reading some of Doc TB's posts on the Memtest86 forum I suspect for most test programs people (including me) tend to run over iPxe they're not going to run properly with the iMac/Macbook in EFI mode anyway as they're expecting to address a PC Bios interface.. so memtest, harddrive test programs, etc are all out unless the Apple unit can be switched to Bios Compatible mode (this is speculation on my part - but appears consistent with available information)

Right now I think my next set of efforts will be around EFI boot loaders, particularly any that can chain off to Bios based loaders. rEFIt is one of the more commonly known Apple ones but hasn't had much development for a while. rEFInd appears to be it's successor and does mention some Bios loader capabilities in it's feature page. So when I've got time I'll try to do some testing with it and see if i can get anywhere.

Jp.