AHCI/ATA_CAM for dummies?

Adam Vande More amvandemore at gmail.com
Mon Dec 14 22:36:58 UTC 2009

On Mon, Dec 14, 2009 at 2:47 PM, Doug Barton <dougb at freebsd.org> wrote:

> b. f. wrote:
> > On 12/14/09, Doug Barton <dougb at freebsd.org> wrote:
> > I believe what they meant in the Intel document was that in order to
> > use certain features supported by AHCI, such as NCQ, the disk drive
> > must also support them.  Your disk drive seems to support NCQ.
> Ok, I believe you. :)  This is clearly not my area.
> > So this does not seem to explain why ahci(4) fails to attach to your
> > SATA controller.  I suspect that your bios or motherboard fails to use
> > AHCI mode.  Maybe there is a later bios revision,
> There is no later BIOS available, at least not from Dell. This is a
> Latitude D620 laptop. And as I said previously, there are no BIOS
> options that mention anything even remotely similar. There are two
> hard drive related options. One is related to making it "slower and
> quieter" vs. "faster and noisier." Guess which one I picked. :)  The
> other is related to power management (DPMI).
> I did look up the spec sheet on the hard drive last night, and
> although it does mention SATA and NCQ it does not explicitly mention
> http://www.hitachigst.com/tech/techlib.nsf/techdocs/50C8DBC2A315A4C786256F400065B756/$file/7K100_SATA_FINAL_DS.pdf
> and
> http://www.hitachigst.com/tech/techlib.nsf/products/Travelstar_7K100
> if you're interested.
> I also didn't see any mentions of jumpers on the drive to enable AHCI,
> which I was kind of hoping for since that's pretty easy to remove.
> > or some jumper
> > settings on the board that will allow it to be enabled.  You may have
> > to talk to the manufacturer.
> I would be willing to dive into that if someone could give me clear
> guidance that one exists. I'm not really eager to open the
> case otherwise.
> > Of course, there is a small chance that
> > there is a problem with our drivers.  Have you tried a live CD of a
> > Linux distro, to see AHCI works with another OS?
> No, but I'm happy to do so. Any suggestions on what distro is most
> likely to succeed, and what to look for? I have used Ubuntu for a
> project in the past with good success but I'd be willing to try
> anything that folks think will work.
> In any case I do appreciate your time on this. I run -current on
> purpose to try out new features, help get them fleshed out from a
> "regular user" perspective, and to expose bugs (often my own of
> course). Better performance and cool new toys don't hurt either ...

A bit of research leads to believe you are SOL on ahci/NCQ for this system
unless you're able to hack a BIOS.  I believe both drive and controller are
capable of running it, but Dell has disabled it as an option for some

Adam Vande More

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