1.\" $NetBSD: acpitz.4,v 1.14 2014/03/18 18:20:39 riastradh Exp $ 2.\" 3.\" Copyright (c) 2003, 2004, 2011 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 16.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 17.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 18.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 19.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25.\" POSSIBILITY OF SUCH DAMAGE. 26.\" 27.Dd January 9, 2011 28.Dt ACPITZ 4 29.Os 30.Sh NAME 31.Nm acpitz 32.Nd ACPI Thermal Zone 33.Sh SYNOPSIS 34.Cd "acpitz* at acpi?" 35.Sh DESCRIPTION 36The 37.Nm 38driver supports so-called 39.Tn ACPI 40.Dq Thermal Zones . 41The temperature can be monitored by the 42.Xr envsys 4 43API or the 44.Xr envstat 8 45command. 46.Pp 47The distinction between 48.Dq active 49and 50.Dq passive 51cooling is central to the abstractions behind 52.Nm . 53These are inversely related to each other: 54.Bl -enum -offset 2n 55.It 56Active cooling means that the system increases the power consumption of the 57machine by performing active thermal management (for example, by turning on 58a fan) in order to reduce the temperatures. 59.It 60Passive cooling means that the system reduces the power consumption of 61devices at the cost of system performance (for example, by lowering the 62.Tn CPU 63frequencies) in order to reduce the temperatures. 64.El 65.Pp 66Only active cooling is currently supported on 67.Nx . 68.Pp 69It should be also noted that the internal 70functioning of these cooling policies vary across machines. 71On some machines the operating system may have little control over 72the thermal zones as the firmware manages the thermal control internally, 73whereas on other machines the policies may be exposed to the implementation 74at their full extent. 75.Sh EVENTS 76The 77.Nm 78driver knows about the active cooling levels, the current 79temperatures, and critical, hot, and passive temperature thresholds 80(as supported by the hardware). 81The driver is able to send events to 82.Xr powerd 8 83when the sensor's state has changed. 84When a Thermal Zone is either critical or 85.Dq hot , 86the 87.Pa /etc/powerd/scripts/sensor_temperature 88script will be invoked with a 89.Em critical-over 90event. 91.Pp 92The critical temperature is the threshold for system shutdown. 93Depending on the hardware, the mainboard will take down the system 94instantly and no event will have a chance to be sent. 95.Sh SEE ALSO 96.Xr acpi 4 , 97.Xr acpifan 4 , 98.Xr envsys 4 , 99.Xr envstat 8 , 100.Xr powerd 8 101.Sh HISTORY 102The 103.Nm 104driver 105appeared in 106.Nx 2.0 . 107.Sh AUTHORS 108.An Jared D. McNeill Aq Mt jmcneill@invisible.ca 109.Sh CAVEATS 110While no pronounced bugs are known to exist, 111several caveats can be mentioned: 112.Bl -bullet 113.It 114Passive cooling is not implemented. 115.It 116There is no user-controllable way to switch between active and passive 117cooling, although the specifications support such transforms on some machines. 118.It 119The 120.Dq hot 121temperature is a threshold in which the system ought to be put into 122.Tn S4 123sleep. 124This sleep state 125.Pq Dq suspend to disk 126is not supported on 127.Nx . 128.El 129