Re: swsusp with highmem, testing wanted
From: Pavel Machek
Date: Thu Mar 25 2004 - 17:24:06 EST
> > Having special "poll" mode for block drivers might do the trick, but
> > thats lot of work.
> Maybe I'm missing something, but why doesn't the regular io paths
(Basically) you want to replace all kernel data with kernel data saved
on disk. How do you do that using normal i/o paths? If you'll read
"new" data 4KB at a time, you'll crash... because you still need "old"
data to do the reading, and "new" data may fit on same physical spot
There are two solutions to this:
* require half of memory to be free during suspend. That way you can
read "new" data onto free spots, then cli and copy
* assume we had special "polling" ide driver that only uses memory
between 0-640KB. That way, I'd have to make sure that 0-640KB is free
during suspending, but otherwise it would work...
Do you see the problem now?
> > Which operations are allowed to access highmem? Can I rely on
> > block device read/write not accessing highmem?
> You mean modify highmem pages, or?
I'd like to know this. Suppose I ask block subsystem to read from disk
into page @1.8GB. All the highmem contains trash. Will block subsystem
be able to work in this situation?
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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