Subject: Re: [PATCH] powerpc: add Book E support to 64-bit hibernation

From: Johannes Berg <[email-masked]>
Date: Fri, 22 Mar 2013 11:58:37 +0100

On Tue, 2013-03-19 at 17:16 -0500, Scott Wood wrote:

> > > I wonder about kernel modules, though flushing 32 MiB wouldn't be
> > > adequate there.
> > 
> > Good question, but would they be running? You have to have everything
> > built in that you need to load the image? Or maybe not, with the
> > userspace image restoration that became possible at some point...
> 
> Is that all that's being restored in this step, or would we be loading  
> all modules that were loaded before suspend (as they're normally not  
> swappable)?  I'm not too familiar with what gets saved where.

Yes, they would be restored since full memory is restored, but the
kernel doing the restore hasn't typically had a chance to load modules.
Although with uswsusp there probably are ways it can already have.

> > Maybe there's a way to completely flush the (i)cache? :-)
> 
> There is, but it's platform-dependent, and not pleasant on our chips  
> (need a displacement flush for L1, and sometimes errata are involved  
> for L2).

:-)

I'll be the last one to tell you what to do, and I really don't remember
for sure why I did the flushing this way. It may very well be wrong for
what I thought I was doing, but it doesn't matter because I didn't need
to be doing it, I can't say any more now, too long ago. Sorry. May you
should ask Rafael what he thinks about flushing.

johannes