1.\" $OpenBSD: ahci.4,v 1.7 2008/04/19 01:18:39 djm Exp $ 2.\" 3.\" Copyright (c) 2006 David Gwynne <dlg@openbsd.org> 4.\" 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. 8.\" 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. 16.\" 17.Dd June 15, 2009 18.Dt AHCI 4 19.Os 20.Sh NAME 21.Nm ahci 22.Nd Advanced Host Controller Interface for Serial ATA 23.Sh SYNOPSIS 24To compile this driver into the kernel, 25place the following line in your 26kernel configuration file: 27.Bd -ragged -offset indent 28.Cd "device ahci" 29.Ed 30.Pp 31Alternatively, to load the driver as a 32module at boot time, place the following line in 33.Xr loader.conf 5 : 34.Bd -literal -offset indent 35ahci_load="YES" 36.Ed 37.Sh DESCRIPTION 38The 39.Nm 40driver provides support for Serial ATA controllers conforming to the 41Advanced Host Controller Interface specification. 42.Pp 43Several AHCI capable controllers also provide a compatibility mode that 44causes them to appear as a traditional ATA controller supported by 45.Xr nata 4 . 46.Pp 47Although 48.Nm 49controllers are actual ATA controllers, the driver emulates SCSI via a 50translation layer. 51.Pp 52Setting the lowest bit (0x1) of the driver flags forces 53.Nm 54to negotiate SATA 1 (1.5 Gb/s) transfer speeds only. 55It may be useful where higher speeds are unstable. 56.Sh SEE ALSO 57.Xr intro 4 , 58.Xr pci 4 , 59.Xr nata 4 , 60.Xr scsi 4 , 61.Xr loader.conf 5 62.Sh HISTORY 63The 64.Nm 65driver first appeared in 66.Dx 2.3 . 67.Sh AUTHORS 68.An -nosplit 69The 70.Nm 71driver was originally written by 72.An David Gwynne Aq dlg@openbsd.org 73and 74.An Christopher Pascoe Aq pascoe@openbsd.org 75for 76.Ox . 77.Pp 78It was ported to 79.Dx 80by 81.An Matt Dillon Aq dillon@apollo.backplane.com 82who added new features such as port multiplier support. 83