[Debian-eeepc-devel] What kernel driver should we be using for the disk? AHCI?

[Phil Endecott]

Phil Endecott wrote:
> Hi again,
>
> Something that struck me when I first looked at the "5 second boot" 
> presentation slides was something called "AHCI" in the graphs; I had 
> never heard of it.  I now discover that it's an interface for SATA 
> controllers, and clearly Arjan's Eee 901 is using it.  Yet my Debian 
> kernel wasn't - even before I started messing around with it.  
> lsmod|grep -i ahci says nothing.  But it does have ahci.ko available.
>
> My suspicion is that we really should be using AHCI, but instead we're 
> using some inferior backward-compatible interface to the same hardware, 
> presumably because modules for both exist and nothing is giving 
> priority to the right one.
>
> Does anyone know anything about this?  Does anyone see ahci in their lsmod?

There's some info here:

http://thread.gmane.org/gmane.linux.kernel/425202/focus=426021

Apparently, this chip is capable of two modes of operation: legacy and 
AHCI.  The BIOS can set the mode, and its PCI ID will change in 
response.  I see the legacy-mode PCI ID 8086:27c4.  The AHCI-mode PCI 
ID is 8086:27c5.  My BIOS doesn't give me any way to change this 
(unless I'm being very blind).  What do other people see?  Clearly 
Arjan's machine has this chip in AHCI mode.  Maybe someone with a 901 
with a newer BIOS (mine is 1101) can comment.


Phil.