Re: Kexec, DMA, and SMP

Corey Minyard
2003-02-10T15:13:00Z

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Suparna Bhattacharya wrote:

|On Mon, Feb 10, 2003 at 07:56:35AM -0600, Corey Minyard wrote:
|
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|>Suparna Bhattacharya wrote:
|>
|>|Yes. It actually saves a formatted compressed dump in memory,
|>|and later writes it out to disk as is.
|>
|>MCL coredump does funny memory shuffling, too. It compresses
|>pages into a contiguous area of memory, and as it runs into output
|>pages that it has not yet compressed, it moves them into pages that
|>it has already compressed and keeps track of where everything is
|
|
|AFAICR, the MCL coredump implementation I'd seen (and used as
|a reference to model some of this code for lkcd) seemed to
|save only a kernel dump (not user space pages), so it would
|use the free and user pages as destination for compressed
|dump. What you are describing sounds a little different and
|closer to what we are doing. I'd be interested in takng a look
|at the implementation you are working with if it actually
|saves the whole memory by making use of pages it has already
|compressed. Could you point me to the code ?

I remembered incorrectly here. I was thinking of bootimg, which does to
some wierd
page shuffling. MCL coredump does not save in a contiguous region, it
keeps a free list
of pages it has alread compressed and allocates destination pages from
it's free list,
and stores those in a map.

- -Corey
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