Re: Hibernation considerations

david
2007-07-17T04:37:15Z

On Mon, 16 Jul 2007, Al Boldi wrote:

> Alan Stern wrote:
>> On Mon, 16 Jul 2007, Al Boldi wrote:
>>> From a kexec'd hibernation kernel pov, both S3 and S4 look conceptually
>>> exactly the same. The only difference is, in S3 the memory is in memory
>>> and in S4 the memory is on storage. All device handling is exactly the
>>> same, so if there is a problem with device handling between the kexec'd
>>> hibernation kernel and the normal kernel, then that would have made
>>> itself visible.
>>
>> You have contradicted yourself. "In S3 the memory is in memory and in
>> S4 the memory is on storage". How does the memory get onto storage?
>> The kexec'd hibernation kernel writes it there. To do so it accesses a
>> storage device.
>>
>> Consequently the device handling _cannot_ be exactly the same in S3 and
>> S4.
>
> Ok, you should have read this in the context of suspending/resuming from/to
> the normal kernel, and in that case they are exactly the same, i.e. kexec -e
> for suspend and kexec -j for resume.
>
> BTW, it would be really helpful if people would actually try the kexec
> hibernation patches, as this may yield a much more constructive discussion.

I would love to, but so far I don't see the nessasary pieces

once I kexec to the new kernel, how can it find out what pages of memory
(and swap) need to be saved?

If i knew that then I could write a trivial perl program to save those
pages with the appropriate headers to make a suspend file.

however, I'm now being told that that suspend file won't work if the
machine is actually powered off, so there's a need to something more for
the wake-up side of things as well.

David Lang