Re: [linux-pm] Re: [patch] hibernation: utilize ACPI hardware signature

[Nigel Cunningham <nigel@nigel.suspend2.net>]

Hi.

Rafael J. Wysocki wrote:
>>>> Is there another mechanism preventing this?
>>> Not at the kernel level, but you can prevent this from happening by running
>>> mkswap on all swap spaces that refuse to come up after a fresh boot.
>> We really should do something about this. It should be possible to
>> handle this properly if something along the following lines was implemented:
>>
>> 1) Each filesystem implements a function taking a pointer to a struct
>> block_device and returns a mount count for that filesystem without
>> making any modifications to the filesystem.
>> 2) Hibernation implementations store the major & minor numbers and mount
>> counts for each mounted filesystem in the image header when hibernating,
>> and recheck those values at resume time. If the mount count on any
>> filesystem has changes, we warn the user, invalidate the image and boot
>> normally.
> 
> That may quickly become complicated.
> 
> For example, boot kernel need not contain all drivers used by the hibernated
> ones, so some filesystems may be physically inaccessible to them.

Mmmm. That's true, and I'd never heard that point raised before or
thought of it myself. Thanks!

Nigel