http://osfree.i2p/forum/viewtopic.php?p=399
For custom kinds of kernels, like OS/2 kernel, a special multiboot kernel can be created. It relocates itself to the address within 1st megabyte (conventional memory), switches back to the real mode and starts IBM's os2ldr, which, in turn, starts OS/2 kernel. For this, the OS/2 kernel specific multiboot kernel must have FileTable and BPB structures passed from freeldr.