Re: [gentoo-user] AHCI/IDE-question

[Mark Knecht]

On Fri, Jan 21, 2011 at 10:45 AM,  <meino.cramer@×××.de> wrote:
>
> Hi,
>
> I got a little confused about the sense or nonsense of AHCI vs. IDE.
>
> I run a ASUS Crosshair IV Formula, which BIOS has a menu entry to
> configure the SATA ports either for IDE or AHCI or RAID. Forget RAID
> for a momen -- I dont use it (nothing against RAID ! ;)
>
> My box uses a linux 2.6.37 vanilla kernel.
>
> The kernel config has been set to
>
>    CONFIG_SATA_AHCI=y
>    # CONFIG_SATA_AHCI_PLATFORM is not set
>
> In the dmesg output I found this:
>
>    pci 0000:00:11.0: set SATA to AHCI mode
>    ahci 0000:00:11.0: AHCI 0001.0200 32 slots 4 ports 3 Gbps 0xf impl SATA mode
>    ahci 0000:07:00.0: AHCI 0001.0000 32 slots 2 ports 3 Gbps 0x3 impl SATA mode
>
> despite the fact that AHCI is disabled in the BIOS settings (using
> IDE).
>
> I did an experiment an disabled AHCI in the kernel (to make the kernel
> settings consistent with the BIOS.)
>
> Result: The kernel did not find the root partition.
>
> In the meanwhile I do not understand all this never more.
>
> Why does the kernel boots only, if the BIOS says "IDE!" and linux
> insists on "AHCI!"...and waht ist the result?
>
> Best regards,
> mcc

Hi meino,
   It's disappointing that Volker insists on sending these pissy
little responses which don't advance the conversation. Sorry for that.

   Not sure I can lend any weight to the argument but it's my belief
that your installation of Gentoo Linux isn't using BIOS to access the
disk at all. Once the system boots and loads the kernel, then the
kernel loads drivers (or uses what you built into the kernel) and
takes over control of the hardware using the AHCI drivers. If the
kernel doesn't use BIOS disk calls (INT13?) then it doesn't care what
the BIOS thinks because the BIOS is not longer involved. It just talks
directly to the hardware.

   I'm happy to be corrected (by Volker I'm sure) but that's my guess
as to what you're seeing.

   Good luck!

Cheers,
Mark