Hello, I am pretty new to OpenBSD and not sure if I should report minor issue to bugs@, but I just found that vgafb(4) device is supported only on macppc and sparc64 (according to src/sys). It has nothing to do with i386 nor with amd64.
But for some reason it's man page sits directly in /usr/share/man/man4 While other platform-specific mans live in /usr/share/man/man4/${machine} (lcd(4) is good example). Ilya.