.\" Copyright (c) 1995,1996 John T. Kohl .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED .\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE .\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, .\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES .\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN .\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .\" $NetBSD: apm.4,v 1.8 1999/12/21 11:27:55 drochner Exp $ .\" .Dd May 18, 1996 .Dt APM 4 i386 .Os .Sh NAME .Nm apm .Nd Advanced Power Management pseudo-device driver .Sh SYNOPSIS .Cd "apm0 at mainbus0" .Fd #include .Pa /dev/apm .Sh DESCRIPTION The .Nm apm driver provides support for the Advanced Power Managment features of some i386 system BIOSes. The driver supports the Advanced Power Management (APM) BIOS Interface Specification (revision 1.2), published jointly by the Intel Corporation and the Microsoft Corporation. .Pp The APM driver's behavior may be adjusted by specifying any of the following kernel configuration options: .Bl -tag -width indent -compact .It Dv APM_NO_IDLE Do not call the BIOS CPU idle function from the system idle loop. (Some systems will hang on certain device accesses, such as sound cards or floppy diskette drives, without this option) .It Dv APM_V10_ONLY Use only the APM revision 1.0 specification calls. (Some systems do not implement APM v1.1 very well, and generate weird events instead of the expected events when the system suspend key is pressed.) .It Dv APM_NO_V12 Don't attach to the BIOS as APM v1.2 compliant device. (In case there are problems with v1.2 support.) .It Dv APM_NO_STANDBY Do not attempt to put the system into standby mode. .It Dv APM_NO_POWEROFF Do not attempt to turn off power when halting the system. .It Dv APM_FORCE_64KSEG Force the length of the APM BIOS code and data segments to 64KB. .It Dv APMDEBUG Enable kernel printout of events received from the APM BIOS. .It Dv APMCALLDEBUG Enable kernel printout of every call to the APM BIOS (this is very noisy). .It Dv APM_NO_POWER_PRINT Do not print power state on console at .Dv APM_POWER_CHANGE events. (Some systems generate the events too frequently, and printing the status may disturb single-user operations.) .It Dv APM_DISABLE_INTERRUPTS Set this to zero if you don't want the kernel to disable interrupts before calling the BIOS. This is required for most IBM ThinkPads, and some other newer laptops. A good indication that you need this is that the machine hangs just after resuming from suspended state. It's unclear if doing this has negative effects on older BIOS, therefore it defaults to one (i.e interrupts are disabled). .El .Pp If no processes are holding open file descriptors to the APM device, the driver will process the APM BIOS events itself. If a process has the device open for write, the driver defers all suspend and standby processing to the user process as long as there is sufficient queue space to store the event for the process. If the device is only open for read, the driver will report events but handle them itself. .Pp The APM device may be opened by multiple readers but only one writer. Multiple readers may fetch the status with .Xr ioctl 2 without worrying about interference, but they must cooperate to share events as only a single event queue is provided. The device may only be .Xr select 2 ed or manipulated with .Xr ioctl 2 ; .Xr read 2 and .Xr write 2 are not supported. The .Xr ioctl 2 calls supported are: .Bl -tag -width indent -compact .It Dv APM_IOC_SUSPEND Initiate an APM suspend mode. This is a deep sleep mode which powers down most devices. The device must be open for writing for this command to succeed. .It Dv APM_IOC_STANDBY Initiate an APM standby mode. This is a light sleep mode from which the system can quickly restore normal operation. The device must be open for writing for this command to succeed. .It Dv APM_IOC_GETPOWER Fetch the current power status into an .Va apm_power_info structure. .Bd -literal struct apm_power_info { u_char battery_state; u_char ac_state; u_char battery_life; u_char spare1; u_int minutes_left; /* estimate */ u_int spare2[6]; }; .Ed .Va battery_state is one of .Dv APM_BATT_HIGH , .Dv APM_BATT_LOW , .Dv APM_BATT_CRITICAL , .Dv APM_BATT_CHARGING , or .Dv APM_BATT_UNKNOWN . .Va ac_state is one of .Dv APM_AC_OFF , .Dv APM_AC_ON , .Dv APM_AC_BACKUP , or .Dv APM_AC_UNKNOWN . .Va battery_life is the percentage estimated remaining normal battery life (or 0 if the BIOS cannot provide an estimate). .Va minutes_left is an estimated remaining lifetime (or 0 if the BIOS cannot provide an estimate). .It Dv APM_IOC_NEXTEVENT Fetch the next event from the APM BIOS into an .Va apm_event_info structure. If no more events are ready, this will return .Dv EAGAIN . .Bd -literal struct apm_event_info { u_int type; u_int index; u_int spare[8]; }; .Ed .Va type is one of the APM event types (APM_STANDBY_REQ through APM_SYS_STANDBY_RESUME). .Va index is the ordinal event sequence number. .El .Sh SEE ALSO .Xr apmd 8 .Sh REFERENCES Advanced Power Management (APM) BIOS Interface Specification (Revision 1.1), Intel Corporation and Microsoft Corporation. Intel order number 241704-001; Microsoft part number 781-110-X01. .Sh HISTORY The .Nm apm pseudo-device driver appeared in .Nx 1.3 .