Plug and Play & power
How devices appear, initialize, and change power state without manual kernel bookkeeping.
What you should already know
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I/O & drivers
From I/O Manager and IRPs through driver stacks and PnP power.
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Why it matters
Modern Windows has to discover devices dynamically and move them through power states safely. This is where hardware lifecycle becomes visible in the OS.
Mental model
PnP answers 'what devices exist?'; power management answers 'what state should they be in now?'
How it works
- 1The PnP manager coordinates enumeration and driver startup.
- 2Power manager policies influence device and processor states.
- 3Drivers must cooperate with both systems to remain stable and efficient.
Key terms
- PnP
- Plug and Play; the infrastructure for discovering and managing hardware dynamically.
- D-state
- A device power state used to describe how active a device currently is.
Closing a laptop lid
Multiple managers and drivers coordinate to reduce power without losing the ability to resume safely.
Common misconception
Power is not just a hardware concern; the OS and drivers must participate together.
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