Re: PATCH: MTRR save and restore.

[Pavel Machek]

Hi!

> I'd like to see the rest of this thread ;)
> 
> > > > > We could add it to suspend scripts, but wouldn't mtrrs fit into the
> > > > > driver model idea? Would you say the same thing about implementing S3
> > > > > support?
> > > > 
> > > > I think going through the driver model is the right thing to
> > > > do.
> > > 
> > > It's useless bloat.
> 
> What exactly is useless bloat? Based on the level of indentation, I'd 
> assume that Richard said that...care to elaborate? 

Richard claims that MTRR save/restore is "useless bloat" and that it
can be don in userspace. He wants userland daemon to do it. I believe
that's bad idea (for reasons like suspend when battery low).

[This is what I said]
> > There's no helper daemon, nor I plan to make one. Notice that mtrr
> > stuff is shared between S3 (== suspend to ram) and swsusp. Both S3 and
> > swsusp can be used to do some pretty important stuff (machine
> > overheats or battery critically low -> suspend somewhere), so I do not
> > think userland daemon is good idea.
> > 
> > It can be dependend on CONFIG_PM; if you still think that's too much
> > bloat, it could be dependend on CONFIG_SLEEP which could be only
> > compiled when S3 or swsusp is selected (but I feel that would be
> > overdesign).
> 
> Yes, that's too much. 
> 
> MTRRs are one interface to an x86 CPU. CPUs are already represented in the
> device tree. The proper thing to do would be to have the CPU suspend/ 
> resume methods save and restore the MTRRs. It still requires an #ifdef in 
> the CPU code, but with a little work, could be massaged down a ways. 

Yep, agreed, mtrrs need in-kernel save/restore support.
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]