The !podev, !poreqlist and !poaction aren’t documented within WinDbg for some reason, but there is a person which has written about them thankfully. These extensions are a must for Stop 0x0A and debugging any issues related to power like Stop 0x9F.
The !popolicy displays information related to the current power policy of the current user.
The !pocaps extensions displays information in relation to the power capabilities of the system, this is ideal for checking if drivers are attempting to use a unsupported sleep state.
The !poreqlist extension will list all outstanding power IRPs from any driver which has called the PoRequestPowerIrp function. The function will create a Power IRP and then send it to the top of the device stack for a given device object.
The list of power IRPs will be shown under the FieldOffset field. The extension will provide the device object, driver object and the nature of the power IRP.
The !poaction extension will provide the current power action, and a list of devices which are currently being powered off or down. It also provides a list of completed IRPs. !poaction may require a Live Debugging session, but I’m not sure on this due to the lack of documentation.
The !podev will provide power related information for a PnP device object.