On 03/19/2013 03:55:34 PM, Johannes Berg wrote:
On Mon, 2013-03-18 at 17:12 -0500, Scott Wood wrote:
> Could you elaborate on why book3s flushes the way it does? What's
> special about the first 32 MiB? If it's to cover kernel code, why
> would that be changing from what's already there?
I was going to say I have no idea, but looking at it again ... this is
in the *resume* code, not the suspend code as I'd assumed, and on
resume
I guess I felt it was safer to not assume it didn't change, since it
could be a slightly different kernel that loaded and restored the
hibernation image?
Wouldn't that be doomed for other reasons?
I wonder about kernel modules, though flushing 32 MiB wouldn't be
adequate there.
It should be the same one, so I guess it should be
exactly the same code, but I guess I wanted to make sure there wasn't
anything weird there. As for why it'd be 32 MiB? No idea. Although
that
really ought to flush all your possible caches anyway, I guess.
It's not a displacement flush (i.e. you don't do a separate load pass
first) -- it just flushes lines if they happen to be present, and
leaves alone anything outside that range. Given that you just finished
copying a bunch of data, most likely what's in the cache is the last
bit of data you copied.
-Scott
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