[PATCH -mm 1/2] kexec jump -v12: kexec jump
vgoyal at redhat.com
Mon Jul 14 09:09:55 EDT 2008
On Sat, Jul 12, 2008 at 11:02:17AM +1000, Nigel Cunningham wrote:
> On Fri, 2008-07-11 at 16:11 -0400, Vivek Goyal wrote:
> > Hi Andrew,
> > We can use this patchset for hibernation, but can it be a better way of doing
> > things than what we already have, I don't know. Last time I had raised
> > this question and power people had various views. In the end, Pavel wanted
> > this patchset to be in. Pavel, can tell more here...
> > To me this patchset looks interesting for couple of reasons.
> > - Looks like an interesting feature where one can have a separate kernel
> > in memory and one can switch between the kernels on the fly. It can
> > be modified to have more than one kernel in memory at a time.
> I'm not sure how useful that would be, though. I already have
> functionality in TuxOnIce which allows you to resume a different image
> instead of powering off (roughly the same thing when combined with not
> removing the image after resuming). It was neat when testing to be able
> to switch back and forth, and I developed the code because I imagined
> that it could form part of the foundation for switching between a login
> screen and users' stored sessions. Is this what you're imagining?
I did not think of that. I thought of two things.
- This can possibly be used for non-disruptive kernel crash dumping, where
if a user wants to capture the snapshot of kernel and then continue
to work. Thought, it might be little heavy weight solution and kernel
state also has changed a bit by the time dump is captured (because of
all the suspend code).
- One can have two distributions installed on a single system and switch
between two booted kernels in few seconds.
> > - So far kexec was one directional. One can only kexec to new kernel and
> > old kernel was gone. Now this patchset makes kexec functionality kind
> > of bidirectional and this looks like logical extension and can lead
> > to intersting use cases in future.
> Ah. You mean keeping both kernels in memory at the same time? In the
> above, I was replacing one image with another.
Yes, here both the kernels will remain in the RAM. In fact it should be
easily possible to keep more than 2 kernels in memory and switch between
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