Install OpenBSD on imac - radeon drm problems

Dear All,

Since i love OBSD, for instance i have it in my panasonic cf-30, dell
precision 690 and a samsung Laptop, i would like to install it in an imac
mid 2011.

The problem is that after install, the first boot always goes blank.

What happened is:
- The install goes as perfect as always.
- When it comes to the first boot, it shows the "error:
[drm:pid0:radeon_read_platform_bios] *ERROR* bios size zero or checksum
mismatch" and CRASH!!!
- I did boot -c, but it freezes on UKC> prompt and do not let me disable
the radeondrm, actually i could only shut it down by the button or power
outlet.
- I did install both 6.2 and 27feb current snapshot and it came with the
same error.

I did boot from the bsd.rd of the installer, but i couldn't save the
dmesg.txt,
as i can see the USB by "sysctl hw.disknames" and it shows something like
"sd0, rd0, sd1, sd2" (sd0 internal disk, rd0 ramdisk, sd1 usb installer,
sd2 usb to backup the dmesg)
but when i do a "disklabel sd2" it returns "no directory" so i could not do
something like:
#disklabel sd2
#mount /dev/sd2a /mnt
#dmesg > /mnt/dmesg.txt
to back up the info and add it to this mail.

Could you please give me a hint ?

Thank you so much in advance :)

Manuel Solis

PD Silly tought: can i manually install the firmware for the radeon card
from the installer shell?
like some creepy thing as: cp raderon.fw
rsd0a:/usr/AllDriverGoesHereWhenItBootsSoItWontCrashAgain/
(it is intentionally silly command but you get the idea)