1 .\" $OpenBSD: ahci.4,v 1.7 2008/04/19 01:18:39 djm Exp $
3 .\" Copyright (c) 2006 David Gwynne <dlg@openbsd.org>
5 .\" Permission to use, copy, modify, and distribute this software for any
6 .\" purpose with or without fee is hereby granted, provided that the above
7 .\" copyright notice and this permission notice appear in all copies.
9 .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 .\" TORTIOUS ACTION, ARISING OUT OF
15 .\" PERFORMANCE OF THIS SOFTWARE.
22 .Nd Advanced Host Controller Interface for Serial ATA
24 To compile this driver into the kernel,
25 place the following line in your
26 kernel configuration file:
27 .Bd -ragged -offset indent
31 Alternatively, to load the driver as a
32 module at boot time, place the following line in
34 .Bd -literal -offset indent
40 driver provides support for Serial ATA controllers conforming to the
41 Advanced Host Controller Interface specification.
43 Several AHCI capable controllers also provide a compatibility mode that
44 causes them to appear as a traditional ATA controller supported by
49 controllers are actual ATA controllers, the driver emulates SCSI via a
52 Setting the lowest bit (0x1) of the driver flags forces
54 to negotiate SATA 1 (1.5 Gb/s) transfer speeds only.
55 It may be useful where higher speeds are unstable.
56 .Sh ADDITIONAL LOADER VARIABLES
58 The following hints may be set in loader.conf to control the
60 driver's behavior. Note that the hint need only exist, so
61 removing the hint requires commenting it out.
63 Usually both the nata and the ahci drivers are loaded. The nata
64 driver will pick up any ata-like devices which the ahci driver
65 misses. If the ahci driver is disabled the nata driver will typically
66 pick up the ahci devices, albeit under the "ad" disk name rather
67 than the "da" disk name.
69 The ahci driver can be told to force a lower-speed 1.5Gb link speed
70 if necessary, and can also be told to refrain from attempting to send
71 certain higher-level ATA commands to initialize ATA features which
72 some devices might not properly implement.
74 .Bd -literal -offset indent
77 hint.ahci.nofeatures=1
89 driver first appeared in
95 driver was originally written by
96 .An David Gwynne Aq dlg@openbsd.org
98 .An Christopher Pascoe Aq pascoe@openbsd.org
105 .An Matt Dillon Aq dillon@apollo.backplane.com
106 who added new features such as port multiplier support.