1 .\" Copyright (c) 2009 Alexander Motin <mav@FreeBSD.org>
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32 .Nd Serial ATA Advanced Host Controller Interface driver
34 To compile this driver into the kernel,
35 place the following lines in your
36 kernel configuration file:
37 .Bd -ragged -offset indent
43 Alternatively, to load the driver as a
44 module at boot time, place the following line in
46 .Bd -literal -offset indent
50 The following tunables are settable from the
53 .It Va hint.ahci. Ns Ar X Ns Va .msi
54 controls Message Signaled Interrupts (MSI) usage by the specified controller.
59 single MSI vector used, if supported (default);
61 multiple MSI vectors used, if supported;
63 .It Va hint.ahci. Ns Ar X Ns Va .ccc
64 controls Command Completion Coalescing (CCC) usage by the specified controller.
65 Non-zero value enables CCC and defines maximum time (in ms), request can wait
66 for interrupt, if there are some more requests present on controller queue.
67 CCC reduces number of context switches on systems with many parallel requests,
68 but it can decrease disk performance on some workloads due to additional
70 .It Va hint.ahcich. Ns Ar X Ns Va .pm_level
71 controls SATA interface Power Management for the specified channel,
72 allowing some power to be saved at the cost of additional command
77 interface Power Management is disabled (default);
79 device is allowed to initiate PM state change, host is passive;
81 host initiates PARTIAL PM state transition every time port becomes idle;
83 host initiates SLUMBER PM state transition every time port becomes idle.
85 driver initiates PARTIAL PM state transition 1ms after port becomes idle;
87 driver initiates SLUMBER PM state transition 125ms after port becomes idle.
89 Some controllers, such as ICH8, do not implement modes 2 and 3 with NCQ used.
90 Because of artificial entering latency, performance degradation in modes
91 4 and 5 is much smaller then in modes 2 and 3.
93 Note that interface Power Management complicates device presence detection.
94 A manual bus reset/rescan may be needed after device hot-plug, unless hardware
95 implements Cold Presence Detection.
96 .It Va hint.ahcich. Ns Ar X Ns Va .sata_rev
97 setting to nonzero value limits maximum SATA revision (speed).
98 Values 1, 2 and 3 are respectively 1.5, 3 and 6Gbps.
100 setting to nonzero value forces driver attach to some known AHCI-capable
101 chips even if they are configured for legacy IDE emulation.
105 This driver provides the
107 subsystem with native access to the
109 ports of AHCI-compatible controllers.
110 Each SATA port found is represented to CAM as a separate bus with one
111 target, or, if HBA supports Port Multipliers, 16 targets.
112 Most of the bus-management details are handled by the SATA-specific
114 Connected ATA disks are handled by the ATA protocol disk peripheral driver
116 ATAPI devices are handled by the SCSI protocol peripheral drivers
122 Driver features include support for Serial ATA and ATAPI devices,
123 Port Multipliers (including FIS-based switching, when supported),
124 hardware command queues (up to 32 commands per port),
125 Native Command Queuing, SATA interface Power Management, device hot-plug
126 and Message Signaled Interrupts.
128 Driver supports "LED" enclosure management messages, defined by the AHCI.
129 When supported by hardware, it allows to control per-port activity, locate
130 and fault LEDs via the
132 API for localization and status reporting purposes.
133 Supporting AHCI controllers may transmit that information to the backplane
134 controllers via SGPIO interface. Backplane controllers interpret received
135 statuses in some way (IBPI standard) to report them using present indicators.
137 AHCI hardware is also supported by ataahci driver from
140 If both drivers are loaded at the same time, this one will be
141 given precedence as the more functional of the two.
145 driver supports AHCI compatible controllers having PCI class 1 (mass storage),
146 subclass 6 (SATA) and programming interface 1 (AHCI).
148 Also, in cooperation with atamarvell and atajmicron drivers of ata(4),
149 it supports AHCI part of legacy-PATA + AHCI-SATA combined controllers,
150 such as JMicron JMB36x and Marvell 88SE61xx.
152 .Bl -tag -width /dev/led/ahcich*.locate
153 .It Pa /dev/led/ahcich*.act
154 activity LED device nodes
155 .It Pa /dev/led/ahcich*.fault
156 fault LED device nodes
157 .It Pa /dev/led/ahcich*.locate
158 locate LED device nodes
170 driver first appeared in
173 .An Alexander Motin Aq mav@FreeBSD.org .