AHCI/ATA_CAM for dummies?

b. f. bf1783 at googlemail.com
Mon Dec 14 08:13:13 UTC 2009

On 12/14/09, Doug Barton <dougb at freebsd.org> wrote:
> b. f. wrote:
>> Hmm.  From what little I know, your chipset should support AHCI, so
>> perhaps your motherboard or bios isn't set up right?:
>> p. 39, 44 of the pdf at:
>> http://www.intel.com/design/chipsets/datashts/307013.htm
> On page 44 it says, "for some features, hardware support in the SATA
> device ..."

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.

> pass0: <Hitachi HTS721010G9SA00 MCZOC10H> ATA-7 SATA 1.x device
> pass0: 100.000MB/s transfers (UDMA5, PIO size 8192bytes)
> Perhaps it does not have the requisite "hardware support" for ahci?

This is the disk drive.  AHCI is for host controllers:


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, or some jumper
settings on the board that will allow it to be enabled.  You may have
to talk to the manufacturer.  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?


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