Power Management Events
There are 12 power events (such as standby, suspend and resume requests, and low battery notifications), plus OEM-defined events, that can be sent from the APM BIOS to the operating system. The APM driver regularly polls for event change notifications.
Power Management Events:
| Name | Code | Comment |
|---|---|---|
| System Standby Request Notification | 0x0001 | |
| System Suspend Request Notification | 0x0002 | |
| Normal Resume System Notification | 0x0003 | |
| Critical Resume System Notification | 0x0004 | |
| Battery Low Notification | 0x0005 | |
| Power Status Change Notification | 0x0006 | |
| Update Time Notification | 0x0007 | |
| Critical System Suspend Notification | 0x0008 | |
| User System Standby Request Notification | 0x0009 | |
| User System Suspend Request Notification | 0x000A | |
| System Standby Resume Notification | 0x000B | |
| Capabilities Change Notification | 0x000C | Due to setup or device insertion/removal |
Power management functions:
| Name | Code | Comment |
|---|---|---|
| APM Installation Check | 0x00 | |
| APM Real Mode Interface Connect | 0x01 | |
| APM Protected Mode 16-bit Interface Connect | 0x02 | Avoids real or virtual86 mode. |
| APM Protected Mode 32-bit Interface Connect | 0x03 | Avoids real or virtual86 mode. |
| APM Interface Disconnect | 0x04 | |
| CPU Idle | 0x05 | Requests system suspend. 0) Clock halted until timer tick interrupt. 1) Slow clock |
| CPU Busy | 0x06 | Driver tells system APM to restore clock speed of the CPU. |
| Set Power State | 0x07 | Set system or device into Suspend/Standby/Off state. |
| Enable/Disable Power Management | 0x08 | |
| Restore APM BIOS Power-On Defaults | 0x09 | |
| Get Power Status | 0x0A | Supports AC status "On backup power". And battery status. |
| Get PM Event | 0x0B | Checks for APM events. Shall be called once per second. |
| Get Power State | 0x0C | |
| Enable/Disable Device Power Management | 0x0D | |
| APM Driver Version | 0x0E | |
| Engage/Disengage Power Management | 0x0F | APM management for a specific device. |
| Get Capabilities | 0x10 | |
| Get/Set/Disable Resume Timer | 0x11 | |
| Enable/Disable Resume on Ring Indicator | 0x12 | |
| Enable/Disable Timer Based Requests | 0x13 | |
| OEM APM Installation Check | 0x80 | Tells if APM BIOS supports OEM hardware dependent functions. |
| OEM APM Function | 0x80 | Access to OEM specific functions. |
Read more about this topic: Advanced Power Management
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