Re: [tip:x86/paravirt] x86-64, gdt: Store/ load GDT for ACPI S3 or hibernate/resume path is not needed.

From: Rafael J. Wysocki
Date: Tue Apr 30 2013 - 18:30:15 EST

On Tuesday, April 30, 2013 05:25:42 PM Konrad Rzeszutek Wilk wrote:
> > > After the 'restore_registers' it returns and we end up called
> > > restore_processor_state() - where we reload the GDT. The reload of
> > > the GDT is not needed as bootup kernel has already loaded the GDT which
> > > is at the same physical location as the the restored kernel.
> >
> > I'm not sure if this particular statement is actually correct. It is correct
> > on 32-bit, but here it is not necessary for the bootup kernel to be the same
> > as the image one. Different kernel version may be used for that even (at
> > least theoretically). So the question is, and I'm quite unsure about the
> > answer, if the GDT of from the bootup kernel is really *guaranteed* to be
> > at the same location (given that those kernels may be really different).
> A bit of testing with different bootup kernel provided me with this error:
> PM: Image mismatch: version

This implies that you tested on an architechture without

> which after a bit of digging pointed me to 'check_image_kernel'. The criteria
> there imply that the different kernel versions or releases cannot be used with
> hibernation.

Only if CONFIG_ARCH_HIBERNATION_HEADER is unset, which is not the case for


I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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