A rewritten version of vmd(8)‘s BIOS memory map handling could soon be appearing in -current.
In short, this nukes some old hacks we've been carrying to communicate things like >4GB of memory to SeaBIOS via CMOS. It assumes vmd(8) properly builds and conveys a bios e820 memory map via the fw_cfg api.
Follow the links to the messages for the full story, test the patches if you feel up to it. While the ETA of the upcoming commit is not yet certain, expect to see this change go in soon.