On Tue, 17 Jul 2007, Jeremy Maitin-Shepard wrote:
"Rafael J. Wysocki" <rjw@xxxxxxx> writes:
[snip]
Rafael, for those of us who aren't thoroughly familiar with all the ins
and outs of the ACPI spec, could you please summarize a list of the
ACPI calls needed in the second and third cases above? Indicate which
ones need to be done from within the original kernel and which should
be done from within a kexec'd hibernation kernel.
Sure.
In the third case (ie. transition to S4) we are supposed to do the following:
(1) Upon entering the sleep state, which IMO can be done _after_ the image
has been saved:
I assume you mean "in order to enter the sleep state", rather than "upon
entering the sleep state". I still don't understand what you mean by
"which IMO can be done _after_ the image has been saved"; as far as I
understand, the last step of this process, "make the platform enter S4",
is almost like a shutdown as far as the kernel is concerned (except for
the tiny detail of having to call those special ACPI methods on resume);
consequently, it would seem that nothing can be done after that step.
* figure out which devices can wake up
* put devices into low power states (wake-up devices are placed in the Dx
states compatible with the wake capability, the others are powered off)
this can't be done by the image-saving kernel if that kernel doesn't know
about the device.
David Lang
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