oui I would like to use the
SPLEEN6x12 WSfont during the entire boot-up process if possible.
That should work. Make sure that a) only
FONT_SPLEEN6x12 is compiled in:
$ fgrep FONT_ /usr/src/sys/arch/amd64/conf/MYKERNEL
# options FONT_BOLD8x16
# options FONT_BOLD16x32
b) both display drivers,
vesafb and your DRMKMS one, use the same display resolution.
Since DRMKMS picks the highest possible one (and you can't change this conveniently), you'll have to make sure that
$ fgrep gop /boot.cfg
menu=Boot normally:gop 0;rndseed /var/db/entropy-file;boot
(On my laptop
genfb picks the 1024x768 mode as default, rather than the 1366x768 chosen by
gop 0 makes it switch to 1366x768.)
Now you should have the same resolution in both drivers, and the also the same font.