ultra tiny characters on console

Hello,

I just installed OpenBSD 6.4 on my Ultra 45.

right before completing the boot process and right before showing the 
login prompt the VGA console does a reset, the screen becomes black and 
when it appears again the character size is so tiny you can barely see 
it and the text console is kind of replicated 6 times in a row on the 
same screen. I would post a picture but I think it's not allowed. I can 
blindly log in as root on the console and launching startx opens X11 
which works, anyway the terminal console is really unusable like this.

Is there a way that I can fix this issue ?

on 6.3 this did not happen.

these are the most significant messages from dmesg they could be related 
to the problem:

radeon_cp: Failed to load firmware "radeon/R300_cp.bin"
error: [drm:pid0:r100_cp_init] *ERROR* Failed to load firmware!
drm:pid0:r300_startup *ERROR* failed initializing CP (-2).
drm:pid0:r300_init *ERROR* Disabling GPU acceleration
Can't enable IRQ/MSI because no handler is installed
Can't enable IRQ/MSI because no handler is installed
Can't enable IRQ/MSI because no handler is installed
radeondrm0: 1280x1024, 8bpp
wsdisplay0 at radeondrm0 mux 1: console (std, sun emulation), using wskbd0

thank you

Rick