Re: Hibernation Redesign

Al Boldi
2007-07-11T04:13:19Z

Jeremy Fitzhardinge wrote:
> Jeremy Maitin-Shepard wrote:
> > In
> > addition, I recall that the Linux boot procedure on x86 and on some
> > other platforms necessarily uses certain low-address memory, like the
> > first 640K, which must be backed up regardless.
>
> Well, the traditional framebuffer/ISA space between 640k and 1M probably
> needs to be identity mapped, but I don't think there's anything in there
> which specifically needs to be save/restored (except framebuffer
> contents, maybe?).
>
> > For these reasons, it seems that it would be easiest to simply backup
> > the first e.g. 16 or 64 MB of memory, and not have to worry about
> > loading the kernel at a non-standard address and specifying a
> > complicated exact memmap. Someone might prove me wrong, though.
>
> Yes, I suppose. You're certain the old kernel's devices are completely
> quiescent at that point?

That's exactly the problem; trying to save a state from within the kernel
would probably necessitate a freezer hack, which we are trying so dearly to
avoid.

The only way the kexec approach may be successful, is by completely relying
on the kexec'd hibernate-mode kernel to save state, otherwise we would be
back to square one. And if that required a special boot procedure for the
kexec'd hibernate-mode kernel, then why not?

Thanks!

--
Al