On 20/06/2016 14:31, Stefan Hajnoczi wrote: > On Mon, Jun 20, 2016 at 08:54:10AM +0200, Paolo Bonzini wrote: > > I wonder if Linux could run as a multiboot-compliant ELF file, and what > > the performance would be... Multiboot omits the real mode stub. > > The Linux boot protocol does not require real mode. I think "64-bit > BOOT PROTOCOL" in Documentation/x86/boot.txt could be used.
Yes, the real mode is only needed to decompress the kernel, to retrieve the e820 memory map, and then invoke the Linux boot protocol. However, neither QEMU nor (I think) GRUB can boot a vmlinux file. So I wondered if it would be possible to compile Linux in a format that is not compressed (for speed) and can be invoked by both QEMU and GRUB. Multiboot seems interesting because it has other advantages. For example it supports modules, so you can use it with an initrd, and it passes the e820 data directly to the loaded kernel. Paolo
