[9fans] VIA VT8237 SATA/RAID i/o errors, dma doesnt work

[Kernel Panic <cinap_lenrek@gmx.de>]

Hello,

I purchased an C7 based machine with VIA VT8237 SATA/RAID:

http://www2.digitalo.de/deeplink.jsp;jsessionid=0FEFF78E7DE9EC893CD54A5B75AA7B60?PROD=948733&EXT=SHOPPING

Have 2 SATA disks attached. They are detected like normal IDE devices.
The Installation of Plan9 worked fine. Created partitions and #k mirror
and setup
venti. I wanted to copy the arenas of my old fileserver to it and then
later format
fossil with the last score, but the machine fails before
finishing/reading the first
arena. :-(

First, i found that DMA was disabled for both drives, so i forced it on
with:
echo dma on >/dev/sdC0/ctl
echo dma on >/dev/sdD0/ctl

...then i get i/o errors in venti and plan9 paniced. so this was not
such a good idea i guess...
reformated all venti partitions and tried again several times with
different bios options
(without DMA, tried both bios SATA IDE and SATA RAID mode):

- after hours of disk activity, sdD0 failed... i tried to read
/dev/sdD0/data and got i/o error instantly and
after reboot worked again.

- after hours of disk activity, i see i/o-error that it cant read
/dev/sdD0/9hal.vtbloom
(venti bloomfilter partition 64MB). and then crashed with poolpanic.

http://plan9.bell-labs.com/wiki/plan9/Supported_PC_hardware/index.html
shows that this
controller should work but it doesnt for me currently.

pci -v shows the as same ids as in the sdata.c driver.

Is anybody using that sata controller? (with multiple SATA disks?) Do i
miss here something?
Are here any special BIOS options i need to get this working?

cinap