[coreboot] Compressed (lzma/nrv2b) elf payload booting

[Ronald Hoogenboom]

Hi,

I'm investigating booting from ROM where the rom is larger than the LPC
mmapped area of the superio. In the 'stream' methods used by elfboot,
there is an option to use compressed payloads, where the stream takes
care of the decompression. But what I've seen is that the payload used
when booting linux kernel directly (Kernel/LAB), the elf payload itself
(kernel-payload.elf as created by buildrom) is already a compressed
image, so the kernel-payload.elf.lzma is not smaller, but bigger than
the non .lzma one.

So my conclusion is that the original kernel decompression is still used
in coreboot, and choosing lzma compression for the elf payload is only a
superfluous extra copy step. Is this correct? Or is this specific to a
64bit kernel, as the elf file holding the 64 bit kernel seems to be a 32
bit elf file.

Regards,
Ronald.