[coreboot] Data exchange between coreboot - seabios - option rom

Christian Gmeiner christian.gmeiner at gmail.com
Tue Aug 21 16:57:56 CEST 2012

2012/8/21 Christian Gmeiner <christian.gmeiner at gmail.com>:
> Hi all,
> my vacation is over and I need to look in some stuff deeper to finally
> get the combination coreboot/seabios fully working. The only missing part
> aside from a lot of testing is the video bios stuff. Here I am working on
> a patch series to extend seabios vga option rom to support flat panels.
> I would like to to use EPI (http://www.epi-standard.org/) for the description
> of the panels. Due EOL changes my target hardware supports different
> kind of flat panels (with different timings). I can detect what panel is used
> with the help of an i2c eeprom. So the normal CBFS will be extended by
> n EPI raw files. And here the troubles begins :)
> 1) Can I add symbolic links during runtime
> It would be fine if somewhere during the boot (coreboot or seabios) I
> can readout
> the needed bytes from the eeprom, decide which EPI file to use and create
> something line a symlink to the choosen one.
> panel.epi -> 640_480_panel_name.epi

As I found out this can be done via nvram. So coreboot set the filename of the
EPI file to use and seabios/... etc can simply use it.

> 2) Can I load a CBFS file in the option rom?
> The idea is to load the EPI raw file and provide it via VBE (vbe_104f15) BIOS
> call. So the geode lx option rom can read out the timing informations via VBE
> and setup the video mode.

It could also be possible to store the EPI data at a defined memory
area where the
option rom can simply check for existing identifiers and checksum.

Any hints are really welcome.

Christian Gmeiner, MSc

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