Re: [patch] hibernation: utilize ACPI hardware signature

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Wednesday, 2 of January 2008, Shaohua Li wrote:
> ACPI defines a hardware signature. BIOS calculates the signature
> according to hardware configure, if hardware changes, the signature will
> change, in this case, S4 resume should fail.

The idea is fine, but I'd prefer to do that in a more straightforward way.
Namely, we can just:
* write the signature into a variable in, for example,
  acpi_hibernation_prepare() (then, the "old" signature value will be
  automatically saved in the image)
* compare it with a the "new" value read from the BIOS in
  acpi_hibernation_leave() and panic if there's a mismatch
* add a configuration option to disable this behavior (just in case)
This way we can avoid modifying the entire generic interface to add the feature
specific to ACPI.

Still, if you want the boot kernel to check the signature, which will be more
elegant (but please note that on x86-64 the boot kernel need not support ACPI
at all), you can use the (recently introduced) architecture part of the image
header for this purpose, without modifying the generic interface.

Greetings,
Rafael