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 The following hints may be set in
57 Note that the hint need only exist, so removing it requires commenting it out.
66 driver will pick up any ata-like devices which the
71 driver is disabled the
73 driver will typically pick up the
75 devices, albeit under the
77 disk name rather than the
80 .Bd -literal -offset indent
86 driver can be told to force a lower-speed 1.5Gb link speed
87 if necessary, and can also be told to refrain from attempting to send
88 certain higher-level ATA commands to initialize ATA features which
89 some devices might not properly implement.
90 .Bd -literal -offset indent
92 hint.ahci.nofeatures=1
95 By default, the driver will use MSI if it is supported.
96 This behavior can be turned off by setting the following tunable:
97 .Bd -literal -offset indent
101 Link power management can be set with the sysctl
102 .Va hw.ahci%d.%d.link_pwr_mgmt
103 to 0 for `disabled', 1 for `medium', and 2 for `aggressive'.
104 Link power state can be read with the sysctl
105 .Va hw.ahci%d.%d.link_pwr_state .
116 driver first appeared in
122 driver was originally written by
123 .An David Gwynne Aq dlg@openbsd.org
125 .An Christopher Pascoe Aq pascoe@openbsd.org
132 .An Matt Dillon Aq dillon@apollo.backplane.com
133 who added new features such as hot-plug and port multiplier support.