8918 loader.efi: add vesa edid support

Review Request #798 - Created Dec. 11, 2017 and updated

Toomas Soome
8918 loader.efi: add vesa edid support

Robert Mustacchi

Can you point out where this is standardized for reviewers?

  1. The vesa.org does offer free download only for members, but while digging for information, I found the https://en.wikipedia.org/wiki/Extended_Display_Identification_Data has quite nice description and references, in particular: http://read.pudn.com/downloads110/ebook/456020/E-EDID%20Standard.pdf as the UEFI 2.7 is referring the EDID api is manipulating E-EDID data and for our purposes this seems to be "good enough" - at least for now. The EDID information is actually more important with BIOS version of the loader, because UEFI is supposed to set usable GOP mode (normally based on EDID or at least 800x600 as minimum), but for bios loader we need to fetch the preferred mode from EDID or fall back to some default.

    So the vesa_edid_info structure is EDID 1.3 structure described in E-EDID pdf section 3.1.