sata-nv and 790i

["J.A. Magallón" <jamagallon@ono.com>]

Hi all...

I recently put my hands on a system with an ASUS P5N64 WS Pro mobo:

http://www.asus.com/products.aspx?l1=3&l2=11&l3=653&l4=0&model=2182&modelmenu=1

It has a nForce 790i Ultra SLI chipset, the part for the SATA controller
is MCP55.

The problem is that linux seems to fail to read the hard drive on boot.
I will explain.

I have tried to install both CentOS 5.2 and Mandriva 2009.0.
For CentOS (has a 2.6.18 kernel), the install seems ok, but when I reboot
into the just intalled system the kernel hangs just after printing
the name of the initrd. Mandriva (2.6.27-rc8) just hungs half the install process.
Live versions of both hang on boot saying they can not find the root
device.

I have found some messages in the net about the MCP55 in that board not
being completeley suppported as AHCI in sata_nv, and that some other
boards work puttin the SATA controller in 'compatible' mode (with
loss of performance).
But I can't find any setting in the P5N64 to put SATA in Compat mode.

Can I do this via some kernel parameters ?
Somabody has this board working ? Do current kernels have better support
for this chipset ?

TIA

-- 
J.A. Magallon <jamagallon()ono!com>     \               Software is like sex:
                                         \         It's better when it's free
Mandriva Linux release 2009.1 (Cooker) for x86_64
Linux 2.6.27.5-desktop-1mnb (gcc 4.3.2 (GCC) #1 Sun Nov