[linux-pm] [PATCH -mm] kexec jump -v9
stern at rowland.harvard.edu
Thu Mar 20 19:01:56 EDT 2008
On Thu, 20 Mar 2008, Rafael J. Wysocki wrote:
> > > >> Well, I've been saying that for I-don't-remember-how-long: on my box, if you
> > > >> use S5 instead of entering S4, the fan doesn't work correctly after the
> > > >> resume. Plain and simple.
> > > >>
> > > >> Perhaps there's a problem with our ACPI drivers that causes this to happen,
> > > >> but I have no idea what that can be at the moment.
> > > >
> > > > IMO it would be worthwhile to track this down. It's a clear indication
> > > > that something is wrong somewhere.
> > > >
> > > > Could it be connected with the way the boot kernel hands control over
> > > > to the image kernel? Presumably ACPI isn't prepared to deal with that
> > > > sort of thing during a boot from S5. It would have to be fooled into
> > > > thinking the two kernels were one and the same.
> > >
> > > It should be easy to test if it is a hand over problem, by turning off
> > > the laptop by placing it in S5 (shutdown -h now) and then booting same
> > > kernel again.
> > Feel free to help with testing.
> > I believe ACPI is simply getting confused by us overwriting memory
> > with that from old image. I don't see how you can emulate it with
> > shutdown.
> Well, in fact ACPI has something called the NVS memory, which we're supposed
> to restore during the resume and which we're not doing. The problem may be
> related to this.
No, it can't be. ACPI won't expect the NVS memory to be restored
following an S5-shutdown. In fact, as far as ACPI is concerned,
resuming from an S5-type hibernation should not be considered a resume
at all but just an ordinary reboot. All ACPI-related memory areas
in the boot kernel should be passed directly through to the image
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