82801 ahci on iBase MB945 motherboard
 

I have been running CentOS5 on this motherboard and it was running just fine with kernel 2.6.18-128.7.1 , however when I tried to update to any kernel newer than that the ahci driver blows off with a failure to reset. I have put printks in the driver and it appears that it is not reading/writing correctly to the control ports. When it reads to see how many "sata ports" are supported it comes back garbage. It should read 0x3f ( for 6 ports ) but it reads 0xce2905eb. This makes me wonder if the control memory has been correctly mapped. I'm in over my head here...

If ahci is causing problems maybe try disabling it in the BIOS and using the sata drivers instead. Make sure you have the SATA drivers you need built-in to the kernel or you won't be able to boot.