Re: khibernation and ACPI

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > The root filesystem is initramfs, so that, the only devices needed by kernel
> > > B is timer.
> > > e. In kernel B, put needed devices back to normal state. 
> > > f. Write memory image of kernel A out
> > > g. Put all devices in quiescent and low power state
> > > h. Execute acpi_enter_sleep_state(ACPI_STATE_S4)
> > 
> > Yes, apart from d. this looks doable.
> > 
> 
> To deal with the issue of d, the following scheme can be used:
> 
> a. Boot kernel A with ACPI on
> b. In kernel A, load the image of a new kernel B with sys_kexec_load
> c. In kernel A, put all devices in quiescent and low power state
> d. In kernel A, kexec kernel B with ACPI on (some devices may be put in
> normal state during boot)
> e. In kernel B, put all devices in quiescent and low power state
> f. In kernel B, Jump back to kernel A
> g. In kernel A, put all devices in normal state
> h. In kernel A, put all devices in low power state
> i. In kernel A, execute _PTS of ACPI
> j. In kernel A, jump to kernel B again
> k. In kernel B, put needed devices back to normal state.
> l. In kernel B, write memory image of kernel A out
> m. In kernel B, put all devices in quiescent and low power state
> n. In kernel B, Execute acpi_enter_sleep_state(ACPI_STATE_S4)

That starts looking pretty complex.

Maybe we should solve the !ACPI case first (should be useful for live
crashdumping, etc)?
								Pavel

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