OK, How Do We Boot a Real Kernel from LinuxBIOS? LOBOS

• LOBOS (Linux OS Boots OS) ג€“ a system call that allows Linux to boot another OS without leaving the 32-bit protected mode or using the BIOS

• Overlaying the kernel (in kernel mode)

  • read a file into memory not occupied by the running kernel
  • move critical structures (page tables, boot arguments, root partition location, log buffer, etc) into a safe place
  • turn off interrupts (point of no return ג€“ check all errors)
  • switch memory to the new page tables
  • copy the final bootstrap code (that copies the kernel to 0x100000 and jumps to it) to a safe place where it will not be overwritten by the new kernel
  • jump to the final bootstrap code that will do its thing