I want to point out that a long, long time ago (I can still remember…) when a linux kernel compile on i386 produced a 512-byte bootsect image in addition to the normal system image. The bootsect could be written to the MBR or floppy boot sector and would load the system image. This meant that there was no need for a separate bootloader.
Actually, I guess it wasn’t so long ago—the functionality was removed sometime in early 2003
. I don’t think I actually remember using the linux bootsector since around 1998.