Re: [PATCH 0/5] Boot protocol changes

Jeremy Fitzhardinge
2007-10-03T00:58:21Z

H. Peter Anvin wrote:
> I'm proposing that the existing bzImage format be retained, but that
> the payload of the decompressor (already a gzip file) simply be
> vmlinux.gz -- i.e. a gzip compressed ELF file, notes and all. A
> pointer in the header will point to the offset of the payload (this is
> new, obviously.)
>
> The decompression stub is adjusted to expect an ELF image, instead of
> a raw binary.

It could, or just treat it as a raw binary at 1M+offset to skip the headers.

> Existing bootloaders (16- or 32-bit) simply load the bzImage the way
> they do now; new bootloaders have the option of accessing the
> vmlinux.gz directly if they either want to load it themselves or want
> to examine the notes.

OK, but that has the same problem as making the payload an ELF file:
32-bit bootloaders which simply jump to 1M will be jumping into data
rather than code - and I got the impression from taking to Eric at KS
that there are such bootloaders.

If that's not an issue, then I still think the payload should be a plain
ELF file (possibly self-decompressing, or just a plain uncompressed
vmlinux, if that's what's desired). Still think making a protected-mode
bootloader do the decompression is the wrong way to go about this; ELF
is enough.

J