Re: [RFC] New Driver Model for 2.5

Patrick Mochel
2001-10-18T17:53:32Z

On Thu, 18 Oct 2001, Jonathan Lundell wrote:

> At 11:08 AM -0500 10/18/01, Taral wrote:
> >On Wed, Oct 17, 2001 at 04:52:29PM -0700, Patrick Mochel wrote:
> >> When a suspend transition is triggered, the device tree is walked first to
> >> save the state of all the devices in the system. Once this is complete, the
> >> saved state, now residing in memory, can be written to some non-volatile
> >> location, like a disk partition or network location.
> >>
> >> The device tree is then walked again to suspend all of the devices. This
> >> guarantees that the device controlling the location to write the state is
> >> still powered on while you have a snapshot of the system state.
> >
> >Aha! A much nicer solution to the problem the ACPI people are having
> >with suspend/resume (ordering problems).
>
> What happens to state changes between the first and second traversal
> of the device tree?

State changes of what?

After the first walk (save_state), you essentially have a snapshot of the
system in memory which can be written to disk, memory, etc.

Once that is done, you disable interrupts and walk the tree again to power
off devices.

-pat