unified bootloader for x86 and arm
 

Is there any possibility of using the same bootloader binary on x86 and arm? Do these architectures have at least something in common which can allow to use the same bootloader?

Here's my problem. I have ipod and i want to install Debian or Sidux for i686 there but I want to keep also Rockbox and original apple os.

Any ideas?

sorry for my english.

NO. ARM is a very different architecture; the CPU initializes and starts up in a different way from x86. In fact x86 has one of the most complicated start-up procedures, probably due to historical (back-compatibility) reasons.

Just to complicate things, ARM is a BI-ENDIAN machine. It defaults to BIG-END on start (I think you can play with some control lines and have it permanently start up in LITTLE-END - it's been too long since I read the manual). For whatever reason, Linux is built as LITTLE-END for the ARM. The ARM bootloader needs to switch to LITTLE-END then load Linux.

If your iPod has an ARM processor, x86 software will not run on it.

Don't confuse the bootloader with the application software or the CPU family - they're all very different things.

The only way that you'd be able to run the same code on an ARM and an x86 would be if that code was interpreted in some way like java, Forth... That would be a useless solution for the problem of a bootloader, because the something would have had to have booted the VM before the bootloader and the bootloader, if it is to be a bootloader, is the first thing that will be run.

You may be slightly cheered by the fact that this seems to have little or nothing to do with your actual problem, as has already been pointed out. But then, as far as I understand your actual problem, that probably isn't soluble either.

Given that Debian is available for a wide range of architectures, your requirement to install Debian for the an arch that is incompatible is perplexing, although not necessarily significant; you probably wouldn't succeed even if you did try to load Debian for the right arch and keep all the Apple software (I'm betting that Apple have tried to make this difficult).

I think I should clarify my intentions.
I use Rockbox and original Apple os on my 5.5G iPod. And I want to use my iPod as external bootable usb-harddrive with Debian for x86.
I know that most x86 systems (i think all) execute bootloader code in MBR.
I don't know how ARM machines boot up but i think that they also use MBR(part of MBR actually).