1.\" $OpenBSD: ahci.4,v 1.13 2018/07/02 15:39:33 kettenis 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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: July 2 2018 $ 18.Dt AHCI 4 19.Os 20.Sh NAME 21.Nm ahci 22.Nd Advanced Host Controller Interface for Serial ATA 23.Sh SYNOPSIS 24.Cd "ahci* at acpi?" 25.Cd "ahci* at fdt?" 26.Cd "ahci* at pci?" 27.Cd "ahci* at jmb?" 28.Sh DESCRIPTION 29The 30.Nm 31driver provides support for Serial ATA controllers conforming to the 32Advanced Host Controller Interface specification. 33.Pp 34Several AHCI capable controllers also provide a compatibility mode that 35causes them to appear as a traditional ATA controller supported by 36.Xr pciide 4 . 37.Pp 38Although 39.Nm 40controllers are actual ATA controllers, the driver emulates SCSI via a 41translation layer. 42.Pp 43Setting the lowest bit (0x1) of the driver flags forces 44.Nm 45to negotiate SATA 1 (1.5 Gb/s) transfer speeds only. 46It may be useful where higher speeds are unstable. 47.Sh SEE ALSO 48.Xr intro 4 , 49.Xr jmb 4 , 50.Xr pci 4 , 51.Xr pciide 4 , 52.Xr scsi 4 53.Sh HISTORY 54The 55.Nm 56driver first appeared in 57.Ox 4.1 . 58.Sh AUTHORS 59.An -nosplit 60The 61.Nm 62driver was written by 63.An David Gwynne Aq Mt dlg@openbsd.org 64and 65.An Christopher Pascoe Aq Mt pascoe@openbsd.org . 66