Windows temporary file of hybernation.

Question

Hi,

Before system put into s4,
windows will flush temporary file to the disk for resume.

There are two questions,

1. Does flush windows temporary file to disk first,
   or call ACPI _PTS Method first?
2. Does restore windows temporary file from disk first,
   or call ACPI _WAK Method first?

Thank you very much.

Answer 1

Hello

Thank you for your question and reaching out. I can understand you are having query\issues related to hibernation.

When you choose to hibernate, the operating system copies all of the RAM data to a single file on the disc (in Windows, this file is hidden and called hiberfil.sys)*. The standard shutdown process then continues.

It looks for the aforementioned file when you turn it on again. If the file is there, you have hibernated your computer, in which case the OS copies its contents directly to RAM.

-> When a hibernate request is made, the following steps occur as the system enters hibernation:

Apps and services are notified

Drivers are notified

User and system state is saved to disk in a compressed format

Firmware is notified

-> Resuming from hibernation

When a system resumes from hibernation.

When a system is powered on, the following steps occur as the system resumes from hibernation:

System POST

System memory is decompressed and restored from the hibernation file

Device initialization

Drivers are restored to the state they were in prior to hibernation

Services are restored to the state they were in prior to hibernation

System becomes available for login

Reference :

https://learn.microsoft.com/en-us/windows/win32/power/system-power-states

https://learn.microsoft.com/en-us/windows-hardware/drivers/kernel/system-sleeping-states

--If the reply is helpful, please Upvote and Accept as answer--

Answer 2

Double post

Answer 3

Hi, Limitless Technology,

Thanks for help.

According to your explanation,
may I consider the sequence be shown at below?

hibernate (s4) : ... -> Acpi.sys -> _PTS -> save hiberfil.sys -> BIOS -> S4
resume from S4: ... -> restore hiberfil.sys -> device initialization -> Acpi.sys -> _WAK -> ....

Thank you very much.

Reference:

_PTS :

https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/07_Power_and_Performance_Mgmt/oem-supplied-system-level-control-methods.html?highlight=_pts#pts-prepare-to-sleep

_WAK:

https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/07_Power_and_Performance_Mgmt/oem-supplied-system-level-control-methods.html?highlight=_pts#wak-system-wake