ACHI support

[Matthew Saltzman]

On Wed, 2007-08-22 at 08:01 -0400, Matthew Saltzman wrote:
> On Wed, 2007-08-22 at 12:58 +0100, Alan Cox wrote:
> > > So in my case, is there a workaround to get it going?
> > > 
> > > 82801HBM/HEM (ICH8M/ICH8M-E) SATA AHCI Controller not detected on boot
> > > in Thinkpad T61
> > 
> > The ICH8M/M-E isn't known by the FC7 install kernel (its a tiny bit too
> > new)
> > 
> > Booting with ata_generic.all_generic_ide=1 as a boot option if the
> > controller is in non-AHCI mode may help, otherwise you need a newer
> > install image from someone.
> 
> I got the install done with the controller in compatibility mode (no
> boot options needed).  But I can't boot the latest production kernel in
> AHCI mode either--stops with a kernel panic.  Is kernel-2.6.22.1-41.fc7
> still not new enough?

Here's my workaround:

        Create /etc/modprobe.d/atapienable containing
        
                options ibata atapi_enabled=1
        
        Create /etc/sysconfig/mkinitrd containing
        
                MODULES="ahci"
        
        to ensure that future kernel initrds will contain the ahci module.
        
        Run
        
                mkinitrd -f --with=ahci /boot/initrd-$(uname -r).img $(uname -r)
        
        to remake the running kernel's initrd.
        
        Reboot and reset the SATA controller mode to AHCI.

Questions:

- Is the first step necessary?

- "hdparm -tT /dev/sda" doesn't show much difference in performance
between compatibility and AHCI modes.  Where should I expect to see a
performance difference, and are there any other settings needed to help
it along?

Thanks. 

-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs