I've been eyeing legacy ISA io/mem range removal, in particular VGA, for some time. Concerning early debug output, it seems that EFI has done this by exporting basic framebuffer info, and Linux has an efifb which uses it. (framebuffer base address + size, stride, pixel format)
Linuxbios currently passes serial console info. Idea: pass key framebuffer info to payloads, so they can use a video/VGA console for early debug output (Linux "earlyprintk").
There is a thread "[coreboot] libpayload: Geode video console support" from a few days ago, which I think is related.
With the libpayload video console support framework, presumably all gfx chips could have their drivers written, yet again. There's a headstart in Linuxbios for initializing RageXL and a couple others, that could be enhanced to print output also.
Is this necessary, or unnecessary code duplication? Could the chip-specific init code be left in Linuxbios, and only a generic video console (ie font + generic rendering to framebuffer code) be provided in libpayload (and/or Linux)?
Keeping it in Linuxbios makes sense for onboard video chips, ie keep board-specific knowledge in the firmware, OTOH, for addin cards, maybe libpayload could have multiple drivers, and pick at runtime...