Re: swsusp: which page should be saved?

[Pavel Machek <pavel@suse.cz>]

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Hi!

> > Ok, I guess it is okay to go in if it stays in -mm for long enough to 
> > get a lot of testing.
> I'll do more tests and back to you. BTW, I wonder if BIOS already saved
> reserved memory (those doing communication with OS) in the 'platform'
> method of S4.

Yep, it should be safe. I bet it will break some obscure machine, but
it will probably fix some obscure machine, too... Just needs lots of testing.

> > > Anyway, skipping kernel text should be safe, isn't it?
> > 
> > It probably is. But you need to save modules. 
> I just consider the region from kernel start(1M) to the end of rodata.
> In my test, the region is about 4M memory. Just adding several lines to
> save 4M memory is worthy.

Well, few lines to save 4MB is nice. OTOH 4MB are saved in about
100msec, and if it brings in hard-to-debug bug on obscure
machine... we did not win much.

> > And we do use some 
> > self-modifying code these days, no? (Called runtime patching or 
> > something like that.) 
> Alternative instructions? The resume OS will do the same modification
> anyway.

Okay, hopefully.

> > Ouch and IIRC top-level pagedir or something 
> > like that lives in kernel "text" -- it is in assembly and wrongly 
> > placed.
> i386 does the right thing and put the pagedir in data segment. x86_64
> not, I think we could clean it up.

This probably should be done, first, and gotten past Andi.

								Pavel
-- 
Picture of sleeping (Linux) penguin wanted...

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