AHCI/ATA_CAM for dummies?

b. f. bf1783 at googlemail.com
Mon Dec 14 06:14:07 UTC 2009

On 12/14/09, Doug Barton <dougb at freebsd.org> wrote:

> One thing I did not include in my previous post was that I actually
> did try adding the ahci device to my kernel config, and didn't get any
> hits. Per your other message tonight I tried again adding ahci and
> siis and booting verbose, no joy. This is on a laptop so I'm not
> really surprised, just disappointed. :)

If you use 'pciconf -lv', is the subclass for your SATA controller
listed as either RAID or AHCI?  If not, either your hardware doesn't
support AHCI, or it is switched into legacy mode (or there is a
problem that mav@ would probably like to know about).  Try looking in
the BIOS setup for a place where you can change the mode.

>> Again, see above.  You may not actually need ata(4).  Even if you do
>> want it, you don't actually need all of ata(4); you can just add the
>> portion you need:
>> device atacore
>> and the chipset-specific parts that correspond to your hardware.
>> Usually, something like:
>> atapci
>> ataahci
>> atanvidia
> The only nvidia thing I have is my graphics card, so I'm assuming I
> could get away with just the first two? Also, how much of an advantage
> does stripping down the ata stuff give? Is it just a bit of kernel
> memory? It's working atm so I'm sort of inclined to leave it alone. :)

I was only offering these three as an example -- the modules that you
should choose depend on your IDE and ATA controller(s).  atapci is the
generic default module, ataahci is required for ahci without ahci(4),
and then there may be a vendor-specific module as well.  Yes, you save
a bit of memory, compile time, and space -- but if you don't want to
use the modular setup, just use the

device ata



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