1.\" LP (Laptop Package) 2.\" 3.\" Copyright (c) 1994 by HOSOKAWA, Tatsumi <hosokawa@mt.cs.keio.ac.jp> 4.\" 5.\" This software may be used, modified, copied, and distributed, in 6.\" both source and binary form provided that the above copyright and 7.\" these terms are retained. Under no circumstances is the author 8.\" responsible for the proper functioning of this software, nor does 9.\" the author assume any responsibility for damages incurred with its 10.\" use. 11.\" 12.\" $FreeBSD$ 13.\" 14.Dd November 1, 1994 15.Dt APM 4 i386 16.Os 17.Sh NAME 18.Nm apm 19.Nd APM BIOS interface 20.Sh SYNOPSIS 21.Cd device apm 22.Sh DEPRECATION NOTICE 23This driver is scheduled for removal prior to the release of 24.Fx 13.0 . 25.Sh DESCRIPTION 26.Nm 27is an interface to the Intel / Microsoft APM (Advanced Power Management) BIOS 28on laptop PCs. 29.Pp 30.Nm 31provides the following power management functions. 32.Bl -enum -offset indent 33.It 34When the system wakes up from suspended mode, 35.Nm 36adjusts the system clock to RTC. 37.It 38When the system wakes up from suspended mode, 39.Nm 40passes a message to 41.Xr syslogd 8 42comprising of system wakeup time and elapsed time during suspended mode. 43.It 44.Nm 45slows CPU clock when there are no system activities (runnable processes, 46interrupts, etc.). 47This function is available only on systems whose APM 48supports CPU idling. 49.It 50.Nm 51exports an application interface as a character device. 52Applications 53can control APM, or retrieve APM status information via this interface. 54.Nm 55exports the following interfaces. 56These symbols are defined in 57.In machine/apm_bios.h . 58.Bl -tag -width 4n -offset indent 59.It Sy APMIO_SUSPEND 60Suspend system. 61.It Sy APMIO_GET 62Get power management information. 63.It Sy APMIO_ENABLE 64.It Sy APMIO_DISABLE 65Enable / Disable power management. 66.It Sy APMIO_HALTCPU 67.It Sy APMIO_NOTHALTCPU 68Control execution of HLT in the kernel context switch routine. 69.It Sy APMIO_GETPWSTATUS 70Get per battery information. 71.Pp 72Some APM implementations execute the HLT 73(Halt CPU until an interrupt occurs) 74instruction in the 75.Dq Em Idle CPU 76call, while others do not. 77Thus enabling this may result in 78redundant HLT executions because 79.Dq Em Idle CPU 80is called from the kernel context switch routine that inherently executes 81HLT. 82This may reduce peak system performance. 83.Pp 84Also the system hangs up if HLT instruction is disabled in the kernel 85context switch routine, and if the APM implementation of the machine 86does not execute HLT in 87.Dq Em Idle CPU . 88On some implementations that do not support CPU clock slowdown, APM 89might not execute HLT. 90.Nm 91disables 92.Sy APMIO_NOTHALTCPU 93operation on such machines. 94.Pp 95The current version of 96.Nm 97does not call 98.Dq Em Idle CPU 99from the kernel context switch routine if clock slowdown is not supported, 100and it executes HLT instruction by default. 101Therefore, there is 102no need to use these two operations in most cases. 103.El 104.Pp 105These interfaces are used by 106.Xr apm 8 . 107.It 108.Nm 109polls APM events and handles the following events. 110.Bl -column "xxxxxxxxxxxxxxxxx" "xxxxxxxxxxxxx" "xxxxxxxx" 111.It Sy "Name" Ta Sy "Action" Ta Sy "Description" 112.It Dv "PMEV_STANDBYREQ" Ta No "suspend system" Ta "standby request" 113.It Dv "PMEV_SUSPENDREQ" Ta No "suspend system" Ta "suspend request" 114.It Dv "PMEV_USERSUSPENDREQ" Ta No "suspend system" Ta "user suspend request" 115.It Dv "PMEV_CRITSUSPEND" Ta No "suspend system" Ta "critical suspend request" 116.It Dv "PMEV_NORMRESUME" Ta No "resume system" Ta "normal resume" 117.It Dv "PMEV_CRITRESUME" Ta No "resume system" Ta "critical resume" 118.It Dv "PMEV_STANDBYRESUME" Ta No "resume system" Ta "standby resume" 119.It Dv "PMEV_BATTERYLOW" Ta No "notify message" Ta "battery low" 120.It Dv "PMEV_UPDATETIME" Ta No "adjust clock" Ta "update time" 121.El 122.El 123.Sh SEE ALSO 124.Xr apm 8 , 125.Xr zzz 8 126.Sh AUTHORS 127.An Tatsumi Hosokawa Aq Mt hosokawa@jp.FreeBSD.org 128.Sh BUGS 129WARNING! 130Many, if not most, of the implementations of APM-bios in laptops 131today are buggy. 132You may be putting your LCD-display and batteries at 133a risk by using this interface. 134(The reason this is not a problem for 135MS-Windows is that they use the real-mode interface.) 136If you see any 137weird behavior from your system with this code in use, unplug the 138power and batteries ASAP, if not immediately, and disable this code. 139.Pp 140We are very interested in getting this code working, so please send your 141observations of any anomalous behavior to us. 142.Pp 143When 144.Nm 145is active, calling the BIOS setup routine by using hot-keys, 146may cause serious trouble when resuming the system. 147BIOS setup programs should be called during bootstrap, or from DOS. 148.Pp 149Some APM implementations cannot handle events such as pushing the 150power button or closing the cover. 151On such implementations, the system 152.Ar must 153be suspended 154.Ar only 155by using 156.Xr apm 8 157or 158.Xr zzz 8 . 159.Pp 160Disk spin-down, LCD backlight control, and power on demand have not 161been supported on the current version. 162