ffs_mountroot: can't find rootvp, after source update to RELENG_5_3

[Eric Penfold]

Hi,

I maintain two FreeBSD servers currently running 5.2p8, and was attempting 
to update one of them to the 5.3 release.

I have cvsup-ed to RELENG_5_3, build world and kernel (GENERIC, and was also 
using GENERIC kernel with 5.2), and then installed kernel.

On reboot, it came up with the following message:

	Mounting root from ufs:/dev/ar0s1a
	no such device 'ar'
	setrootbyname failed
	ffs_mountroot: can't find rootvp
	Root mount failed: 6

If I listed boot devices, at the prompt after the above message, it showed 
the ad4s1a, ad6s1a that ar0s1a maps onto, etc.

I was able to unload the kernel and revert back to 5.2, so it would appear 
to be a problem with the new kernel not recognising the raid array on the 
server.

The controller is detected as:

kernel: atapci1: <SiI 3112 SATA150 controller> port 0x4010
-0x401f,0x4038-0x403b,0x4040-0x4047,0x403c-0x403f,0x4048-0x404f mem 
0xfc300400-0 xfc3005ff irq 27 at device 3.0 on pci3

Unfortunately I dont have the boot message from the failed 5.3 kernel, cos 
it didnt log it anywhere, and the server is remote - so repeating it isnt 
easy. I think I remember seeing a similar message under 5.3 though.

After some research, I find that raid support for SiI0680 ATA controller is 
not working in this release. Although this is not the same controller as I 
have, the symptoms seem similar - "configuration stored under 5.2 or prior 
may be corrupted".

Is it possible, likely, or even safe, that I would need to (re)run the 
"atacontrol create" commands to recreate the raid array under a 5.3 kernel - 
and can this be done without destorying the data/partitions already there?

Any other suggestions as to how to work around it - without having to 
(re)install the OS from scratch?

Cheers,

Eric.