Re: [GIT PULL] x86 setup: correct booting on 486 (revised)

H. Peter Anvin
2007-11-06T01:32:18Z

Jeremy Fitzhardinge wrote:
>
> Another thing it would be nice to add is an elf-note-like notion so that
> the kernel can export arbitrary key/value data to the bootloader (ie,
> the converse of the bootloader->kernel value list). Xen currently does
> this via ELF notes, but any semanically equivalent mechanism would do.
> It's probably simpler than trying to work out how to mush bzimage and
> ELF together.
>

I suspect all we need is an offset-pointer field pointing into the
kernel image. As far as the kernel build process is concerned, it
becomes a section in the boot/compressed link script. That offset then
needs to get exported to the setup.elf link stage and there adjusted to
become a file offset.

The ELF note format is sane enough, although it looks like it's not
self-terminating, so we'd either need an offset and a length field, or
adopt the convention that namesz = descsz = type = 0 terminates the
block (I prefer the latter, myself.) We also need the notes documented,
obviously.

-hpa